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	<front>
		<journal-meta>
			<journal-id journal-id-type="publisher-id">rac</journal-id>
			<journal-title-group>
				<journal-title>Revista argentina de cardiología</journal-title>
				<abbrev-journal-title abbrev-type="publisher">Rev Argent Cardiol</abbrev-journal-title>
			</journal-title-group>
			<issn pub-type="ppub">0034-7000</issn>
			<issn pub-type="epub">1850-3748</issn>
			<publisher>
				<publisher-name>Sociedad Argentina de Cardiología</publisher-name>
			</publisher>
		</journal-meta>
		<article-meta>
			<article-id pub-id-type="doi">10.7775/rac.es.v93.i2.20876</article-id>
			<article-id pub-id-type="publisher-id">00003</article-id>
			<article-categories>
				<subj-group subj-group-type="heading">
					<subject>ARTÍCULO ORIGINAL</subject>
				</subj-group>
			</article-categories>
			<title-group>
				<article-title>Fibrilación auricular <italic>de novo</italic> en el infarto agudo de miocardio con elevación del segmento ST. Análisis del Registro ARGEN-IAM-ST</article-title>
				<trans-title-group xml:lang="en">
					<trans-title>De <italic>novo</italic> Atrial Fibrillation in ST-Elevation Acute Myocardial Infarction. Analysis of the ARGEN-IAM-ST Registry</trans-title>
				</trans-title-group>
			</title-group>
			<contrib-group>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0009-0004-9939-267X</contrib-id>
					<name>
						<surname>JANCHES QUIÑONEZ</surname>
						<given-names>JULIA</given-names>
					</name>
					<xref ref-type="aff" rid="aff1b"><sup>1</sup></xref>
				</contrib>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0009-0005-7426-7976</contrib-id>
					<name>
						<surname>VARGAS PARRAGA</surname>
						<given-names>ELENA</given-names>
					</name>
					<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
				</contrib>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0009-0003-9913-5000</contrib-id>
					<name>
						<surname>CHUEKE</surname>
						<given-names>BRENDA</given-names>
					</name>
					<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
				</contrib>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0009-0000-2519-0099</contrib-id>
					<name>
						<surname>PACCE</surname>
						<given-names>ORNELLA</given-names>
					</name>
					<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
				</contrib>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0009-0009-3584-2180</contrib-id>
					<name>
						<surname>CARDOZO</surname>
						<given-names>DANIELA</given-names>
					</name>
					<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
				</contrib>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0000-0002-2400-3105</contrib-id>
					<name>
						<surname>D'IMPERIO</surname>
						<given-names>HERALDO</given-names>
					</name>
					<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
				</contrib>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0000-0001-5896-760X</contrib-id>
					<name>
						<surname>ZAPATA</surname>
						<given-names>GERARDO</given-names>
					</name>
					<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
				</contrib>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0009-0003-0201-043X</contrib-id>
					<name>
						<surname>VILLARREAL</surname>
						<given-names>RICARDO</given-names>
					</name>
					<xref ref-type="aff" rid="aff3"><sup>3</sup></xref>
					<xref ref-type="fn" rid="fn1"><sup>MTSAC</sup></xref>
				</contrib>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0000-0002-2195-5020</contrib-id>
					<name>
						<surname>SOSA LIPRANDI</surname>
						<given-names>ALVARO</given-names>
					</name>
					<xref ref-type="aff" rid="aff3"><sup>3</sup></xref>
					<xref ref-type="fn" rid="fn1"><sup>MTSAC</sup></xref>
				</contrib>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0000-0002-7969-4505</contrib-id>
					<name>
						<surname>PEREA</surname>
						<given-names>JOAQUIN</given-names>
					</name>
					<xref ref-type="aff" rid="aff3"><sup>3</sup></xref>
					<xref ref-type="fn" rid="fn1"><sup>MTSAC</sup></xref>
				</contrib>
				<on-behalf-of>ARGEN-IAM-ST Group</on-behalf-of>
			</contrib-group>
			<aff id="aff1">
				<label>1</label>
				<institution content-type="original">Sanatorio Güemes Servicio Cardiología </institution>
				<institution content-type="normalized">Sanatorio Güemes</institution>
				<institution content-type="orgdiv1">Servicio Cardiología</institution>
				<country country="AR">Argentina</country>
			</aff>
			<aff id="aff2">
				<label>2</label>
				<institution content-type="original">Federación Argentina de Cardiología</institution>
				<institution content-type="normalized">Federación Argentina de Cardiología</institution>
				<country country="AR">Argentina</country>
			</aff>
			<aff id="aff3">
				<label>3</label>
				<institution content-type="original">Sociedad Argentina de Cardiología </institution>
				<institution content-type="normalized">Sociedad Argentina de Cardiología</institution>
				<country country="AR">Argentina</country>
			</aff>
			<aff id="aff1b">
				<label>1</label>
				<institution content-type="original">Sanatorio Güemes Servicio Cardiología </institution>
				<institution content-type="normalized">Sanatorio Güemes</institution>
				<institution content-type="orgdiv1">Servicio Cardiología</institution>
				<country country="AR">Argentina</country>
				<email>Juliajanches@hotmail.com</email>
			</aff>
			<author-notes>
				<corresp id="c1">
					<label> Dirección para correspondencia </label><bold>:</bold> Julia Janches Quiñones. Departamento de investigación, Sanatorio Güemes. Francisco Acuña de Figueroa 1228, 7.° Piso, CP 1180AAX, Buenos Aires, Argentina Tel./Fax 49598200 E-mail: <email>Juliajanches@hotmail.com</email>
				</corresp>
				<fn fn-type="conflict" id="fn2">
					<label>Declaración de conflicto de intereses</label>
					<p> Los autores declaran que no tienen conflicto de intereses. (Ver formulario de conflicto de intereses en la web)</p>
				</fn>
			</author-notes>
			<!--<pub-date date-type="pub" publication-format="electronic">
				<day>16</day>
				<month>05</month>
				<year>2025</year>
			</pub-date>
			<pub-date date-type="collection" publication-format="electronic">
				<season>Mar-Apr</season>
				<year>2025</year>
			</pub-date>-->
			<pub-date pub-type="epub-ppub">
				<season>Mar-Apr</season>
				<year>2025</year>
			</pub-date>
			<volume>93</volume>
			<issue>2</issue>
			<fpage>99</fpage>
			<lpage>107</lpage>
			<history>
				<date date-type="received">
					<day>07</day>
					<month>12</month>
					<year>2024</year>
				</date>
				<date date-type="accepted">
					<day>18</day>
					<month>02</month>
					<year>2025</year>
				</date>
			</history>
			<permissions>
				<license license-type="open-access" xlink:href="https://creativecommons.org/licenses/by-nc/4.0/" xml:lang="es">
					<license-p>Este es un artículo publicado en acceso abierto bajo una licencia Creative Commons</license-p>
				</license>
			</permissions>
			<abstract>
				<title>RESUMEN</title>
				<sec>
					<title>Introducción:</title>
					<p> La fibrilación auricular (FA) es la complicación arrítmica más frecuente en pacientes con síndrome coronario agudo (SCA), con una incidencia entre 2,3% y 21%.</p>
				</sec>
				<sec>
					<title>Objetivos:</title>
					<p> Determinar la incidencia y predictores de FA <italic>de novo</italic> en pacientes con infarto agudo de miocardio con elevación del segmento ST (IAMCEST).</p>
				</sec>
				<sec>
					<title>Material y métodos:</title>
					<p> Se analizó la base de datos del registro continuo ARGEN-IAM-ST. La estadística descriptiva fue la convencional. Para reducir la dimensionalidad e identificar aquellas variables asociadas con el desenlace de interés, se utilizaron algoritmos de <italic>Machine Learning</italic> y se realizó un análisis multivariable de regresión logística para identificar aquellos factores asociados a la presencia de FA <italic>de novo</italic>. Los mismos fueron incluidos en un modelo de clasificación final que fue evaluado por medio de curva ROC. Se consideró un valor de p &lt; 0,05 como estadísticamente significativo.</p>
				</sec>
				<sec>
					<title>Resultados:</title>
					<p> Se incluyeron 7292 pacientes con IAMCEST. El 4,3% presentó FA <italic>de novo</italic> durante la internación. Este grupo era más añoso (67 vs. 60 años, p &lt;0,001). Al ingreso hospitalario, presentaba mayor frecuencia cardíaca, un score de Killip y Kimball mayor y una menor fracción de eyección del ventrículo izquierdo (FEVI). Estos pacientes tuvieron mayor incidencia de accidente cerebrovascular (2,5% vs. 0,8% p = 0,002) y muerte intrahospitalaria (23,3% vs. 8,2%, p &lt;0,001), pero la FA <italic>de novo</italic> no fue predictor independiente de mortalidad. La variable edad estratificada (50 a 59 años: OR 2,16, IC 95% 1,11-2,73; 60 a 69 años: OR 1,77, IC 95% 1,07-2,96; 70 a 100 años: OR 3,98, IC 95% 2,60-6,26) ; el score Killip y Kimball (B: OR 1,72 IC 95% 1,19-2,46; C: OR 1,09, IC 95% 0,31-2,91, D: OR 2,48, IC 95% 1,60-3,78), la presencia de taquicardia (OR 2,41, IC95% 1,74-3,31) y una FEVI &lt;35 % (OR 1,62, IC95% 1,74-3,31) fueron predictores independientes de FA <italic>de novo</italic> intrahospitalaria posterior a un IAMCEST. El modelo presentó un área bajo la curva ROC (ABC ROC) de 0,73, con sensibilidad y especificidad de 77 y 62 %, respectivamente.</p>
				</sec>
				<sec>
					<title>Conclusiones:</title>
					<p> la FA <italic>de novo</italic> fue una complicación relativamente frecuente. Factores como la edad, frecuencia cardíaca, el perfil hemodinámico al ingreso y la función ventricular mostraron ser predictores de FA <italic>de novo</italic> post infarto en la internación. Sin embargo, ésta no se asoció de manera independiente con la mortalidad intrahospitalaria.</p>
				</sec>
			</abstract>
			<trans-abstract xml:lang="en">
				<title>ABSTRACT</title>
				<sec>
					<title>Background:</title>
					<p> Atrial fibrillation (AF) is the most frequent arrhythmic complication in patients with acute coronary syndrome (ACS), and its incidence ranges between 2.3% and 21%.</p>
				</sec>
				<sec>
					<title>Objective: </title>
					<p>To determine the incidence and predictors of <italic>de novo</italic> AF in patients with ST-segment elevation myocardial infarction (STEMI).</p>
				</sec>
				<sec>
					<title>Methods: </title>
					<p>The database of the ARGEN-IAM-ST continuous registry was analyzed. Conventional descriptive statistics were used. To reduce dimensionality and identify those variables associated with the outcome of interest, Machine Learning algorithms were used, and a multivariate logistic regression analysis was performed to identify those factors associated with <italic>de novo</italic> AF. These were included in a final ranking model which was assessed by using the receiver operating characteristic (ROC) curve. A p-value &lt;0.05 was considered statistically significant.</p>
				</sec>
				<sec>
					<title>Results: </title>
					<p>We included 7292 patients with STEMI. A total of 4.3% had <italic>de novo</italic> AF during hospitalization. This group was older (67 vs. 60 years, p &lt;0.001), with higher heart rate and Killip and Kimbal score and lower left ventricular ejection fraction (LVEF) on admission. These patients had a higher incidence of stroke (2.5% vs. 0.8% p = 0.002) and in-hospital death (23.3% vs. 8.2%, p &lt;0.001), but <italic>de novo</italic> AF was not an independent predictor of mortality. The following variables were independent predictors of in-hospital <italic>de novo</italic> AF after STEMI: stratified age (50 to 59 years: OR 2.16, 95% CI 1.11-2.73; 60 to 69 years: OR 1.77, 95% CI 1.07-2.96; 70 to 100 years: OR 3.98, 95% CI 2.60-6.26), Killip and Kimball score (B: OR 1.72 95% CI 1.19-2.46; C: OR 1.09, 95% CI 0.31-2.91, D: OR 2.48, 95% CI 1.60-3.78), tachycardia (OR 2.41, 95% CI 1.74-3.31) and LVEF &lt;35% (OR 1.62, 95% CI 1.74-3.31). The area under the ROC curve (AUC ROC) of the model was 0.73; the sensitivity and specificity were 77% and 62%, respectively.</p>
				</sec>
				<sec>
					<title>Conclusion:</title>
					<p><italic>De novo</italic> AF was a relatively frequent complication. Factors such as age, heart rate, hemodynamic profile on admission and ventricular function were shown to be predictors of <italic>de novo</italic> AF after a myocardial infarction during hospitalization. However, <italic>de novo</italic> AF was not independently associated with in-hospital mortality.</p>
				</sec>
			</trans-abstract>
			<kwd-group xml:lang="es">
				<title>Palabras clave:</title>
				<kwd>Fibrilación auricular</kwd>
				<kwd>Infarto de miocardio con elevación del segmento ST</kwd>
			</kwd-group>
			<kwd-group xml:lang="en">
				<title>Key words:</title>
				<kwd>Atrial fibrillation</kwd>
				<kwd>ST-elevation myocardial infarction</kwd>
			</kwd-group>
			<counts>
				<fig-count count="4"/>
				<table-count count="2"/>
				<equation-count count="0"/>
				<ref-count count="22"/>
				<page-count count="9"/>
			</counts>
		</article-meta>
	</front>
	<body>
		<sec sec-type="intro">
			<title>INTRODUCCIÓN</title>
			<p>La fibrilación auricular (FA) es la arritmia cardíaca sostenida más común en adultos, con una prevalencia que se encuentra en aumento a lo largo de las últimas décadas debido al envejecimiento poblacional y al aumento de la sobrevida de otras condiciones cardíacas. (<xref ref-type="bibr" rid="B1">1</xref>) Se asocia con un mayor riesgo de eventos tromboembólicos, (<xref ref-type="bibr" rid="B2">2</xref>) deterioro cognitivo, (<xref ref-type="bibr" rid="B3">3</xref>) insuficiencia cardíaca, hospitalizaciones y muerte. (<xref ref-type="bibr" rid="B4">4</xref>) </p>
			<p>A su vez, es la complicación arrítmica más frecuente en pacientes con síndrome coronario agudo (SCA), con una incidencia de entre 2,3 y 21%. (<xref ref-type="bibr" rid="B5">5</xref>) En Argentina tenemos en este contexto una incidencia de FA <italic>de novo</italic> del 3,2%, observada en el registro ARGEN-IAM-ST. (<xref ref-type="bibr" rid="B6">6</xref>) A lo largo de las últimas décadas y con el avance del tratamiento invasivo y médico, su incidencia parecería haber disminuido. (<xref ref-type="bibr" rid="B6">6</xref>) Múltiples estudios han evaluado las características clínicas de los pacientes que presentaron FA <italic>de novo</italic> posterior a un SCA. Se observó que los principales predictores fueron la edad avanzada, la presencia de signos de insuficiencia cardíaca y la taquicardia al ingreso hospitalario. Estos predictores se han sostenido tanto en estudios realizados en la era fibrinolítica como en la actualidad, con la disponibilidad del tratamiento percutáneo. </p>
			<p>(<xref ref-type="bibr" rid="B7">7</xref>,<xref ref-type="bibr" rid="B8">8</xref>)</p>
			<p>Tanto en la población general como en los pacientes que cursan un SCA, la presencia de FA se asocia con peor pronóstico. Cuando la FA se desarrolla <italic>de novo</italic> dentro del marco de un SCA se asocia a mayor morbimortalidad. (<xref ref-type="bibr" rid="B9">9</xref>,<xref ref-type="bibr" rid="B10">10</xref>) A su vez, múltiples estudios observacionales han evidenciado que los pacientes en los que coexisten un SCA y FA <italic>de novo</italic> tienen menos chances de recibir tratamiento antitrombótico apropiado. (<xref ref-type="bibr" rid="B11">11</xref>,<xref ref-type="bibr" rid="B12">12</xref>) Sin embargo, faltan estudios que analicen predictores y pronóstico de estos pacientes dentro del marco del tratamiento invasivo y médico recomendado por las últimas guías. </p>
			<p>Los objetivos de este estudio fueron evaluar la incidencia de FA <italic>de novo</italic> durante la internación por un infarto agudo de miocardio con elevación del segmento ST (IAMCEST) y determinar predictores asociados con su desarrollo.</p>
		</sec>
		<sec sec-type="materials|methods">
			<title>MATERIAL Y MÉTODOS</title>
			<sec>
				<title>Diseño y población del estudio</title>
				<p>Se trata de un estudio observacional y retrospectivo a partir del análisis del registro continuo de Infarto agudo de miocardio con elevación del segmento ST (ARGEN-IAM-ST), que incluye pacientes con IAMCEST de numerosos centros de la República Argentina. Su protocolo fue publicado previamente, y se encuentra activo desde el año 2015. (<xref ref-type="bibr" rid="B13">13</xref>,<xref ref-type="bibr" rid="B14">14</xref>) El protocolo fue registrado en ClinicalsTrials.gov NCT 2458885. Se realizó un corte para el análisis de este trabajo hasta mayo del 2024. </p>
			</sec>
			<sec>
				<title>Definiciones y desenlace de interés</title>
				<p>Nuestro desenlace de interés fue la FA <italic>de novo</italic> durante la internación. La definimos como FA en aquellos pacientes que se habían presentado a su ingreso con un electrocardiograma (ECG) en ritmo sinusal y que durante su evolución presentaron como complicación un episodio de FA. La misma fue modelada como una variable binaria. Excluimos de esta definición a aquellos pacientes que presentaban como antecedente FA y aleteo auricular.</p>
			</sec>
			<sec>
				<title>Análisis estadístico</title>
				<p>Las variables continuas se expresan como media y desviación estándar (DE) o mediana y rango intercuartílico (RIC), según su tipo de distribución. La<italic>s</italic> variables edad y frecuencia cardíaca fueron analizadas por estratos. Las variables cualitativas se expresan como frecuencias absolutas y relativas. Las variables cualitativas se compararon mediante la prueba de chi cuadrado o la prueba exacta de Fisher, mientras que las variables continuas con distribución paramétrica y no paramétrica se compararon mediante la prueba de t de Student y la prueba de la U de Mann Whitney, respectivamente. </p>
				<p>Para reducir la dimensionalidad e identificar aquellas variables asociadas con nuestro desenlace de interés, se utilizó el algoritmo de <italic>Machine Learning</italic> Boruta. (<xref ref-type="bibr" rid="B15">15</xref>) Para garantizar que la selección de variables fuera estable y reproducible, el algoritmo realizó hasta 50 iteraciones, permitiendo evaluar de manera robusta la importancia de cada predictor en la clasificación de FA <italic>de novo</italic>. Además, se monitoreó su desempeño durante el proceso para verificar la coherencia en la selección de características. Con aquellas variables de mayor peso se realizó análisis multivariable por medio de regresión logística para identificar los factores asociados de manera independiente a la presencia de FA <italic>de novo</italic>. Los modelos fueron entrenados y testeados en dos bases de datos distintas generadas de forma aleatoria a partir de la base de datos general. El desempeño de los modelos y su capacidad de discriminación fue evaluada a través de la generación de curvas ROC (<italic>Receiver Operating Characteristic</italic>). Dado que el objetivo del modelo fue maximizar la sensibilidad para identificar la mayor cantidad de casos de FA <italic>de novo</italic>, se seleccionó el punto de corte óptimo a partir de la curva ROC con el criterio de mayor sensibilidad posible, manteniendo una especificidad clínicamente aceptable. Para evaluar la bondad de ajuste del modelo se utilizó la prueba de Hosmer Lemeshow. La asociación entre los predictores y la incidencia de eventos se expresó como Odds ratio (OR) con sus intervalos de confianza del 95% (IC 95%). Además, se realizó un modelo multivariable para explorar la FA <italic>de novo</italic> como predictor independiente de mortalidad. Todas las pruebas fueron a dos colas y la significación estadística se estableció en un valor de p &lt;0,05.</p>
				<p>El análisis se realizó con R Studio, versión 1.4.1106 (The R Foundation for Statistical Computing, Viena, Austria). </p>
			</sec>
			<sec>
				<title>Consideraciones éticas</title>
				<p>El protocolo del registro Argen IAM-ST fue aprobado por el comité de ética de la Sociedad Argentina de Cardiología.</p>
			</sec>
		</sec>
		<sec sec-type="results">
			<title>RESULTADOS</title>
			<sec>
				<title>Características basales de la población</title>
				<p>Se incluyeron en total 7292 pacientes que presentaron IAMCEST y evidencia de ritmo sinusal en el ECG de ingreso, de los cuales el 79% pertenecían al género masculino, con una mediana (RIC) de edad de 61 (53-69) años. Las características basales se muestran en la <xref ref-type="table" rid="t1">Tabla 1</xref>.</p>
				<p>
					<table-wrap id="t1">
						<label>Tabla 1:</label>
						<caption>
							<title>Características Clínicas Basales de los Participantes con y sin FA de <italic>novo</italic></title>
						</caption>
						<table frame="hsides" rules="groups">
							<colgroup>
								<col/>
								<col/>
								<col/>
								<col/>
								<col/>
							</colgroup>
							<thead>
								<tr style="border: 0; background-color:#ab0534;color:#ffffff;">
									<th align="left"> </th>
									<th align="center">Global</th>
									<th align="center">No FA <italic>de novo</italic></th>
									<th align="center">FA <italic>de novo</italic></th>
									<th align="center">p</th>
								</tr>
							</thead>
							<tbody>
								<tr style="background-color: #e3aea9;">
									<td align="left"> n</td>
									<td align="center">7292</td>
									<td align="center">6974</td>
									<td align="center">318</td>
									<td align="right"> </td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Género Masculino, n (%)</td>
									<td align="center">5754 (79)</td>
									<td align="center">5512 (79)</td>
									<td align="center">248 (78)</td>
									<td align="center"> 0,705</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Edad, años, mediana (RIC)</td>
									<td align="center">61 (53-69)</td>
									<td align="center">60 (53-68)</td>
									<td align="center">67(60-77)</td>
									<td align="center">&lt;0,001</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">IMC, kg/m<sup>2</sup>, mediana (RIC)</td>
									<td align="center">27,65 (25,47-30,61)</td>
									<td align="center">27,68 (25,51-30,76)</td>
									<td align="center">27,41 (25,28-29,97)</td>
									<td align="center">0,041</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">DM, n (%)</td>
									<td align="center">1980 (27,2)</td>
									<td align="center">1900 (27,2)</td>
									<td align="center">80 (25,2)</td>
									<td align="center">0,451</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">TBQ, n (%)</td>
									<td align="center">591 ( 8,1)</td>
									<td align="center">563 ( 8,1)</td>
									<td align="center">28 ( 8,8)</td>
									<td align="center">0,717</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">DLP, n (%)</td>
									<td align="center">2662 (36,5)</td>
									<td align="center">2553 (36,6)</td>
									<td align="center">109 (34,3)</td>
									<td align="center">0,433</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">HTA, n (%)</td>
									<td align="center">3870 (53,1)</td>
									<td align="center">3661 (52,5)</td>
									<td align="center">209 (65,7)</td>
									<td align="center">&lt;0,001</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Enfermedad coronaria previa, n (%)</td>
									<td align="center">897 (12,3)</td>
									<td align="center">846 (12,1)</td>
									<td align="center">51 (16,0)</td>
									<td align="center">0,047</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Betabloqueantes, n (%)</td>
									<td align="center">3635 (50,0)</td>
									<td align="center">3519 (50,5)</td>
									<td align="center">120 (37,7)</td>
									<td align="center">&lt;0,001</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">IECA, n (%)</td>
									<td align="center">3301 (45,4)</td>
									<td align="center">3178 (45,6)</td>
									<td align="center">129 (40,6)</td>
									<td align="center">0,090</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Glucemia, mg/dL, mediana (RIC) </td>
									<td align="center">135 (113-179)</td>
									<td align="center">134 (113-177)</td>
									<td align="center">153 (124-212,50)</td>
									<td align="center">&lt;0,001</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Creatinina, mg/dL, mediana (RIC)</td>
									<td align="center">0,97 (0,80-1,18)</td>
									<td align="center">0,97 (0,80-1,17)</td>
									<td align="center">1,08 (0,90-1,40)</td>
									<td align="center">&lt;0,001</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Motivo de la ATC, n (%)</td>
									<td align="center"> </td>
									<td align="center"> </td>
									<td align="center"> </td>
									<td align="center">0,949</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Primaria</td>
									<td align="center">5003 (91,1)</td>
									<td align="center">4887 (70,1)</td>
									<td align="center">207 (65,1)</td>
									<td align="center"> </td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Fármaco invasiva</td>
									<td align="center">273 (5,0)</td>
									<td align="center">646 (9,3)</td>
									<td align="center">37 (11,6)</td>
									<td align="center"> </td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Rescate</td>
									<td align="center">154 (2,8)</td>
									<td align="center">976 (14,0)</td>
									<td align="center">45 (14,2)</td>
									<td align="center"> </td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Electiva</td>
									<td align="center">59 (1,1)</td>
									<td align="center">465 (6,7)</td>
									<td align="center">29 (9,1)</td>
									<td align="center"> </td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">TAS, mm Hg, media (DE)</td>
									<td align="center">131 (29)</td>
									<td align="center">132 (29)</td>
									<td align="center">121 (29)</td>
									<td align="center">&lt;0,001</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">FC, lpm, media (DE)</td>
									<td align="center">80 (19)</td>
									<td align="center">80 (18)</td>
									<td align="center">86 (26)</td>
									<td align="center">&lt;0,001</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Killip y Kimball, n (%)</td>
									<td align="center"> </td>
									<td align="center"> </td>
									<td align="center"> </td>
									<td align="center">&lt;0,001</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">A</td>
									<td align="center">5485 (77,0)</td>
									<td align="center">5456 (78,2)</td>
									<td align="center">153 (48,1)</td>
									<td align="center"> </td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">B</td>
									<td align="center">1024 (14,4)</td>
									<td align="center">955 (13,7)</td>
									<td align="center">90 (28,3)</td>
									<td align="center"> </td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">C</td>
									<td align="center">100 (1,4)</td>
									<td align="center">95 (1,4)</td>
									<td align="center">8 (2,5)</td>
									<td align="center"> </td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">D</td>
									<td align="center">516 (7,2)</td>
									<td align="center">468 (6,7)</td>
									<td align="center">67 (21,1)</td>
									<td align="center"> </td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Tiempo puerta-balón, min, mediana (RIC)</td>
									<td align="center">84 (47-147)</td>
									<td align="center">91(50, 175)</td>
									<td align="center">92, (51,25- 209,75)</td>
									<td align="center">0,439</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Tiempo ventana, min, mediana (RIC)</td>
									<td align="center">230 (135-440)</td>
									<td align="center">252,50 (146-510)</td>
									<td align="center">289,50 (162,25- 612,25)</td>
									<td align="center">0,019</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">ATC a múltiples vasos en procedimiento inicial, n (%)</td>
									<td align="center">351 (6,4)</td>
									<td align="center">360 (5,2)</td>
									<td align="center">26 (8,2)</td>
									<td align="center">0,026</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">FSVI, n (%)</td>
									<td align="center"> </td>
									<td align="center"> </td>
									<td align="center"> </td>
									<td align="center">&lt;0,001</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Normal</td>
									<td align="center">2397 (37,4)</td>
									<td align="center">2660 (38,1)</td>
									<td align="center">75 (23,6)</td>
									<td align="center"> </td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Deterioro leve</td>
									<td align="center">1842 (28,7)</td>
									<td align="center">1994 (28,6)</td>
									<td align="center">58 (18,2)</td>
									<td align="center"> </td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Deterioro moderado</td>
									<td align="center">1397 (21,8)</td>
									<td align="center">1466 (21,0)</td>
									<td align="center">93 (29,2)</td>
									<td align="center"> </td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Deterioro grave </td>
									<td align="center">774 (12,1)</td>
									<td align="center">854 (12,2)</td>
									<td align="center">92 (28,9)</td>
									<td align="center"> </td>
								</tr>
							</tbody>
						</table>
						<table-wrap-foot>
							<fn id="TFN1">
								<p>ATC: angioplastia transluminal coronaria; DE: desviación estándar; DM: diabetes mellitus; DLP: dislipidemia; FA: fibrilación auricular; FC: frecuencia cardíaca; FSVI: función sistólica del ventrículo izquierdo; HTA: hipertensión arterial; IECA: inhibidores de la enzima convertidora de angiotensina; IMC: índice de masa corporal; lpm: latidos por minuto; RIC: rango intercuartílico; TAS: tensión arterial sistólica; TBQ: tabaquismo</p>
							</fn>
						</table-wrap-foot>
					</table-wrap>
				</p>
				<p>Se identificó que el 4,3% de la muestra presentó FA <italic>de novo</italic> durante la internación. Estos pacientes eran mayores que aquellos que permanecieron libres de FA (mediana de edad de 67 vs. 60 años; p &lt;0,001). No encontramos diferencias entre los grupos respecto del índice de masa corporal (IMC), diabetes mellitus y dislipidemia. Sin embargo, el 53,1% presentaba hipertensión arterial (HTA), con mayor prevalencia en el grupo de pacientes que evolucionó con FA durante la internación (65,7% vs. 52,5%; p &lt;0,001). A su vez, el antecedente de enfermedad coronaria, presente en el 12,3% de la muestra total, también fue más frecuente en el grupo con FA <italic>de novo</italic> (16% vs. 12,1%; p = 0,047). </p>
				<p>En cuanto a las estrategias de reperfusión, en el 91% del total de pacientes se realizó angioplastia primaria, en el 5% estrategia farmacoinvasiva, en el 2,8% angioplastia de rescate y en el 1,1% angioplastia electiva, sin diferencias significativas entre los grupos de estudio. Sin embargo, se realizó angioplastia a múltiples vasos en el procedimiento inicial en mayor proporción en los pacientes que evolucionaron con FA durante la internación. No se evidenciaron diferencias significativas en cuanto al tratamiento del vaso culpable del IAM.</p>
				<p>En cuanto al tratamiento con betabloqueantes e inhibidores de la enzima convertidora al ingreso, encontramos un menor uso de estos en aquellos pacientes con FA <italic>de novo:</italic> 50% vs. 37% (p = 0,001) y 45% vs. 40% (p = 0,090) respectivamente.</p>
				<p>Al ingreso hospitalario, aquellos pacientes que evolucionaron con FA presentaban mayor frecuencia cardíaca (86 lpm vs. 80 lpm; p &lt;0,001) y, en el laboratorio, mayores valores de glucemia, con mediana (RIC) de 153 mg/dL (124-212) vs. 134 mg/dL (113-177), p&lt;0,001, y de creatinina: 1,08 mg/dL (0,90-1,40) vs. 0,97 mg/dL (0,8-1,17), p&lt;0,001. </p>
				<p>Este grupo de pacientes también presentó mayor tiempo de isquemia total (medianas de 289 min vs. 252 min; p=0,019), un score de Killip y Kimball más grave (p&lt;0,001) y una menor fracción de eyección del ventrículo izquierdo (FEVI) (p &lt;0,001). </p>
			</sec>
			<sec>
				<title>Eventos intrahospitalarios</title>
				<p>La presencia de FA <italic>de novo</italic> se asoció con una mayor incidencia de accidente cerebrovascular (ACV) isquémico (2,5% vs. 0,8%; p = 0,002) y más días de internación (medianas de 6 vs. 4 días; p &lt;0,001). En relación con la muerte intrahospitalaria por todas las causas también fue mayor en el grupo con FA <italic>de novo</italic> (23,3% vs. 8,2%; p &lt;0,001) (<xref ref-type="table" rid="t2">Tabla 2</xref>)</p>
				<p>
					<table-wrap id="t2">
						<label>Tabla 2:</label>
						<caption>
							<title><bold>Eventos intrahospitalarios de los participantes con y sin FA de <italic>novo</italic>
</bold></title>
						</caption>
						<table frame="hsides" rules="groups">
							<colgroup>
								<col/>
								<col/>
								<col/>
								<col/>
								<col/>
							</colgroup>
							<thead>
								<tr style="border: 0; background-color:#ab0534;color:#ffffff;">
									<th align="left"> </th>
									<th align="center">Global</th>
									<th align="center">No FA de <italic>novo</italic></th>
									<th align="center">FA de <italic>novo</italic></th>
									<th align="center">p</th>
								</tr>
							</thead>
							<tbody>
								<tr style="background-color: #e3aea9;">
									<td align="left"> n</td>
									<td align="center">7292</td>
									<td align="center">6974</td>
									<td align="center">318</td>
									<td align="right"> </td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">ReIAM, n (%)</td>
									<td align="center"> 123 (1,7)</td>
									<td align="center"> 113 (1,6)</td>
									<td align="center"> 10 (3,1)</td>
									<td align="center"> 0,066</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">ACV, n (%)</td>
									<td align="center"> 61 (0,8) </td>
									<td align="center"> 53 (0,8) </td>
									<td align="center"> 8 (2,5) </td>
									<td align="center"> 0,002</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Shock cardiogénico, n (%)</td>
									<td align="center"> 682 (9,4)</td>
									<td align="center"> 576 (8,3)</td>
									<td align="center"> 106 (33,3)</td>
									<td align="center"> &lt;0,001</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">IC, n (%)</td>
									<td align="center"> 967 (13,3)</td>
									<td align="center"> 818 (11,7)</td>
									<td align="center"> 149 (46,9)</td>
									<td align="center"> &lt;0,001</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Muerte hospitalaria, n (%)</td>
									<td align="center">591 (8,1)</td>
									<td align="center">563 (8,1)</td>
									<td align="center">28 (8,8)</td>
									<td align="center">0,717</td>
								</tr>
								<tr style="background-color: #e3aea9;">
									<td align="left">Días de internación, mediana (RIC)</td>
									<td align="center"> 4 (3- 6)</td>
									<td align="center"> 4 (3-6)</td>
									<td align="center"> 6 (4-11)</td>
									<td align="center">&lt;0,001</td>
								</tr>
							</tbody>
						</table>
						<table-wrap-foot>
							<fn id="TFN2">
								<p>ACV: accidente cerebrovascular; FA: fibrilación auricular; IC: insuficiencia cardíaca; RIC: rango intercuartílico; ReIAM: reinfarto</p>
							</fn>
						</table-wrap-foot>
					</table-wrap>
				</p>
			</sec>
			<sec>
				<title>Selección de variables relevantes </title>
				<p>Mediante el algoritmo Boruta se realizó una selección automatizada con el objetivo de identificar las variables con mayor relevancia en la predicción de FA <italic>de novo</italic>. En el análisis, las variables Killip y Kimball, frecuencia cardíaca y FEVI, se identificaron como las de mayor importancia, seguidas por género, edad, dislipidemia y creatinina. En la<xref ref-type="fig" rid="f1">Figura 1</xref>, se presentan las medias de importancia de cada variable en el ranking obtenido. Posteriormente, estas variables fueron incluidas en el modelo de regresión logística multivariable para evaluar su asociación con el desenlace. </p>
				<p>
					<fig id="f1">
						<label>Fig. 1</label>
						<caption>
							<title>Importancia de las variables predictoras de FA de novo </title>
							<p>FEVI: fracción de eyección del ventrículo izquierdo; MV: múltiples vasos; proc: procedimiento; Tiempo ventana: tiempo en minutos desde el inicio de los síntomas hasta el comienzo de la infusión en el caso de fibrinolíticos o hasta el insuflado del balón en el caso de ATC. </p>
						</caption>
						<graphic xlink:href="1850-3748-rac-93-02-99-gf1.jpg"/>
					</fig>
				</p>
			</sec>
			<sec>
				<title><bold>Análisis multivariable. Predictores independientes de FA <italic>de novo</italic>
</bold></title>
				<p>Aquellas variables de mayor peso asociadas a presencia de FA <italic>de novo</italic> fueron incluidas en un modelo multivariable de regresión logística. La variable edad estratificada (50 a 59 años, 60 a 69 años y 70 a 100 años) se asoció independientemente a incidencia de FA <italic>de novo</italic> (OR 1,72, IC95% 1,11-2,73; OR 1,77, IC95% 1,07-2,96; OR 3,98, IC95% 2,60-6,25 respectivamente). También fueron predictores independientes la presentación clínica según el score Killip y Kimball (B: OR 1,72, IC95% 1,19-2,46; C: OR 1,09, IC95% 0,315-2,90; D: OR 2,48, IC95%1,60-3,78), la presencia de taquicardia (OR 2,41, IC95% 1,74-3,31) y una FEVI deteriorada (&lt;35%) (OR 1,62, IC95% 1,04-2,50) (<xref ref-type="fig" rid="f2">Figura 2</xref>). Para evaluar el rendimiento del modelo, se construyó una curva ROC, obteniendo un área bajo la curva (ABC) de 0,733 (IC 95% 0,698-0,769). Se determinó el punto de corte óptimo en 0,10, seleccionado con el objetivo de maximizar la sensibilidad. Con este umbral, el modelo identificó correctamente el 77% de los pacientes con FA <italic>de novo</italic> (sensibilidad)<bold> </bold>y el<bold> </bold>62% de los pacientes sin FA <italic>de novo</italic> (especificidad)<bold>.</bold> Este punto de corte representa el umbral donde el balance entre sensibilidad y especificidad resulta clínicamente más adecuado para la detección de FA <italic>de novo</italic> (<xref ref-type="fig" rid="f3">Figura 3</xref>). La bondad de ajuste del modelo fue evaluada mediante el test de Hosmer-Lemeshow, que mostró un buen ajuste (χ² = 5,33, p = 0,618).</p>
				<p>
					<fig id="f2">
						<label>Fig. 2</label>
						<caption>
							<title>Predictores de FA de novo </title>
							<p>FA: fibrilación auricular ; FEVI: fracción de eyección ventricular izquierda</p>
						</caption>
						<graphic xlink:href="1850-3748-rac-93-02-99-gf2.jpg"/>
					</fig>
				</p>
				<p>
					<fig id="f3">
						<label>Fig. 3</label>
						<caption>
							<title>Curva ROC del modelo predictor de FA de novo </title>
							<p>ABC: área bajo la curva; E: especificidad; IC95%: intervalo de confanza del 95%; S: sensibilidad</p>
						</caption>
						<graphic xlink:href="1850-3748-rac-93-02-99-gf3.jpg"/>
					</fig>
				</p>
			</sec>
			<sec>
				<title><bold>Análisis multivariable: FA <italic>de novo</italic> como predictor independiente de mortalidad</bold></title>
				<p>Se incluyó la FA <italic>de novo</italic> junto a las principales variables relacionadas con la mortalidad intrahospitalaria en un modelo multivariable. Se observó que la FA <italic>de novo</italic> no se comportó como predictor independiente de mortalidad intrahospitalaria (OR 0,79, IC95% 0,41-1,50) (<xref ref-type="fig" rid="f4">Figura 4</xref>)</p>
				<p>
					<fig id="f4">
						<label>Fig. 4</label>
						<caption>
							<title>Predictores de mortalidad hospitalaria </title>
							<p>FA: fibrilación auricular</p>
						</caption>
						<graphic xlink:href="1850-3748-rac-93-02-99-gf4.jpg"/>
					</fig>
				</p>
			</sec>
		</sec>
		<sec sec-type="discussion">
			<title>DISCUSIÓN </title>
			<p>Se presentan los datos de incidencia de FA <italic>de novo</italic> durante la internación por IAMCEST del registro ARGEN-IAM-ST. En esta ocasión se excluyeron los casos con registro de FA en el ECG de ingreso o con antecedente de esta, para evaluar las consecuencias de este evento luego del IAM. La incidencia fue 4,3%, y los hallazgos sugieren una asociación con mayor número de eventos intrahospitalarios, así como una estancia hospitalaria más prolongada. Por otro lado, encontramos que ciertos factores como la edad, la presencia de insuficiencia cardíaca evaluada con el <italic>score</italic> Killip y Kimball, la taquicardia y el deterioro de la FEVI fueron predictores independientes de FA <italic>de novo</italic> durante la internación. Dichos predictores fueron incorporados en un modelo de clasificación para predecir FA <italic>de novo,</italic> que presentó un ABC de 0,733, (IC 95% 0,698-0,769)</p>
			<p>La FA y el SCA son dos entidades cardiológicas frecuentes por lo que a lo largo de los años se han desarrollado múltiples estudios con el objetivo de analizar la relación entre ambas patologías. El riesgo de FA <italic>de novo</italic> aumenta un 60-77% en pacientes cursando un IAM. (<xref ref-type="bibr" rid="B16">16</xref>) En la era fibrinolítica, los estudios randomizados GUSTO-I (1997) y GUSTO-III (2000), compararon distintos esquemas fibrinolíticos en pacientes con IAMCEST, y destacaron una incidencia de FA <italic>de novo</italic> posterior a un SCA de 7,9% y 6,5% respectivamente. (<xref ref-type="bibr" rid="B8">8</xref>, <xref ref-type="bibr" rid="B17">17</xref>) Por otro lado, en el año 2003, se publicó el estudio prospectivo observacional OACIS, que analizó pacientes con IAM (con y sin elevación del segmento ST) tratados con angioplastia percutánea coronaria dentro de las 24 h, en donde se observó una incidencia de FA <italic>de novo</italic> de 7,7%. (<xref ref-type="bibr" rid="B18">18</xref>) En cuanto a resultados nacionales, datos del registro Buenos Aires I, que incluía pacientes con síndrome coronario agudo sin elevación del segmento ST (SCASEST), demostraron una incidencia de FA <italic>de novo</italic> intrahospitalaria de 4,3% y 7,7% en pacientes con IAM y angina inestable, respectivamente. (<xref ref-type="bibr" rid="B19">19</xref>) De manera similar, en una publicación previa, el registro ARGEN-IAM-ST mostró una incidencia de FA <italic>de novo</italic> de 3,2%, y los factores predisponentes fueron la edad avanzada, el antecedente de HTA y la enfermedad coronaria previa. (<xref ref-type="bibr" rid="B6">6</xref>) Definitivamente no se cuenta con estudios aleatorizados que hayan comparado la incidencia de FA <italic>de novo</italic> en pacientes con IAMCEST tratado con fibrinolíticos vs. angioplastia primaria y las diferencias en las poblaciones y las metodologías de los estudios publicados impiden una correcta evaluación de la incidencia de esta complicación, y de si se ve afectada por el tipo de revascularización. </p>
			<p>En nuestra cohorte, la edad se comportó como un predictor independiente de FA <italic>de novo</italic>. Específicamente en el estrato de edad de 70-100 años es donde observamos el mayor impacto, con un OR de 3,98. Al igual que la FA fuera del contexto de un SCA, la edad estuvo íntimamente relacionada con la incidencia de esta arritmia. En uno de los estudios con mayor número de pacientes, realizado a partir de la base de datos del <italic>Cooperative Cardiovascular Project</italic> publicado en el año 2000, (<xref ref-type="bibr" rid="B11">11</xref>) que incluyó únicamente pacientes ≥65 años, se observó que la tasa de FA <italic>de novo</italic> posterior a un SCA era del 22%, significativamente mayor a la de estudios que incluyeron pacientes de todas las edades. Adicionalmente, en la revisión realizada en el 2009 por Schmitt et al., se observó que todos los estudios publicados desde 1992 hasta el 2007 identificaron a la edad avanzada como predictor independiente de FA <italic>de novo</italic> posterior a un SCA. (<xref ref-type="bibr" rid="B20">20</xref>)</p>
			<p>Si bien la FA es la arritmia supraventricular más frecuente en la población general, su incidencia es notablemente mayor en pacientes con insuficiencia cardíaca (IC). Estas dos patologías se relacionan estrechamente entre sí, y cada una perpetúa la presencia de la otra. (<xref ref-type="bibr" rid="B21">21</xref>) En nuestro análisis, pudimos observar que la presencia de IC evaluada a través del <italic>score</italic> Killip y Kimball se asoció de manera independiente con la presencia de FA <italic>de novo,</italic> al igual que en los estudios previamente mencionados GUSTO-I y III. Cabe destacar un subanálisis del estudio internacional GRACE, que incluyó más de </p>
			<p>21 000 pacientes con SCA, clasificándolos según la presencia de FA <italic>de novo</italic>, FA previa y sin FA, el cual identificó a un <italic>score</italic> de Killip y Kimball ≥ 2 como predictor independiente de FA <italic>de novo.</italic> (<xref ref-type="bibr" rid="B22">22</xref>) De la misma forma, la presencia de taquicardia, probablemente secundaria a la presencia de IC, también fue un predictor de FA <italic>de novo</italic> en nuestro estudio y en el previamente mencionado. Estos resultados traducen el impacto del estado hemodinámico dentro de los mecanismos fisiopatológicos de la FA en el marco de un SCA, y señalan que un paciente con un estado hemodinámico alterado (IC, taquicardia y/o hipotensión) tiene mayor riesgo de presentar FA.</p>
			<p>Paralelamente, el deterioro grave de la FEVI (&lt;35%) también se comportó como predictor independiente de FA <italic>de novo</italic> en nuestro análisis. Si bien la asociación entre la disfunción ventricular y la presentación clínica al ingreso (reflejada en el score de Killip y Kimball y la frecuencia cardíaca) es clara, otros estudios no han evidenciado esta variable como predictor independiente de FA <italic>de novo</italic>. </p>
		</sec>
		<sec>
			<title>LIMITACIONES</title>
			<p>El registro ARGEN-IAM-ST es un registro de participación voluntaria sin estrategia de auditoría. Si bien se realizó análisis multivariable por regresión no podemos descartar por completo que haya variables no consideradas que hayan podido alterar nuestros resultados. Además, si bien se trata de un estudio multicéntrico, solo representa la realidad de los centros participantes. Por último, no podemos determinar el momento de la internación en el cual se produjo la FA, por lo cual no podemos estudiar la relación temporal de la misma.</p>
		</sec>
		<sec sec-type="conclusions">
			<title>CONCLUSIONES</title>
			<p>En esta cohorte de pacientes del registro ARGEN-IAM-ST, la FA <italic>de novo</italic> fue una complicación relativamente frecuente. Factores como la edad, frecuencia cardíaca, el perfil hemodinámico al ingreso y la función ventricular mostraron ser predictores de una FA <italic>de novo</italic> en la internación por un IAM. Sin embargo, la FA <italic>de novo</italic> no se asoció de manera independiente con la mortalidad intrahospitalaria. </p>
		</sec>
	</body>
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					<contrib-id contrib-id-type="orcid">0009-0003-9913-5000</contrib-id>
					<name>
						<surname>CHUEKE</surname>
						<given-names>BRENDA</given-names>
					</name>
					<xref ref-type="aff" rid="aff4"><sup>1</sup></xref>
				</contrib>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0009-0000-2519-0099</contrib-id>
					<name>
						<surname>PACCE</surname>
						<given-names>ORNELLA</given-names>
					</name>
					<xref ref-type="aff" rid="aff4"><sup>1</sup></xref>
				</contrib>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0009-0009-3584-2180</contrib-id>
					<name>
						<surname>CARDOZO</surname>
						<given-names>DANIELA</given-names>
					</name>
					<xref ref-type="aff" rid="aff4"><sup>1</sup></xref>
				</contrib>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0000-0002-2400-3105</contrib-id>
					<name>
						<surname>D'IMPERIO</surname>
						<given-names>HERALDO</given-names>
					</name>
					<xref ref-type="aff" rid="aff5"><sup>2</sup></xref>
				</contrib>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0000-0001-5896-760X</contrib-id>
					<name>
						<surname>ZAPATA</surname>
						<given-names>GERARDO</given-names>
					</name>
					<xref ref-type="aff" rid="aff5"><sup>2</sup></xref>
				</contrib>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0009-0003-0201-043X</contrib-id>
					<name>
						<surname>VILLARREAL</surname>
						<given-names>RICARDO</given-names>
					</name>
					<xref ref-type="aff" rid="aff6"><sup>3</sup></xref>
					<xref ref-type="fn" rid="fn1"><sup>MTSAC</sup></xref>
				</contrib>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0000-0002-2195-5020</contrib-id>
					<name>
						<surname>SOSA LIPRANDI</surname>
						<given-names>ALVARO</given-names>
					</name>
					<xref ref-type="aff" rid="aff6"><sup>3</sup></xref>
					<xref ref-type="fn" rid="fn1"><sup>MTSAC</sup></xref>
				</contrib>
				<contrib contrib-type="author">
					<contrib-id contrib-id-type="orcid">0000-0002-7969-4505</contrib-id>
					<name>
						<surname>PEREA</surname>
						<given-names>JOAQUIN</given-names>
					</name>
					<xref ref-type="aff" rid="aff6"><sup>3</sup></xref>
					<xref ref-type="fn" rid="fn1"><sup>MTSAC</sup></xref>
				</contrib>
				<on-behalf-of>ARGEN-IAM-ST Group</on-behalf-of>
			</contrib-group>
			<aff id="aff4">
				<label>1</label>
				<institution content-type="original">Sanatorio Güemes Cardiology Service </institution>
				<institution content-type="orgname">Sanatorio Güemes</institution>
				<institution content-type="orgdiv1">Cardiology Service</institution>
			</aff>
			<aff id="aff5">
				<label>2</label>
				<institution content-type="original">Argentine Federation of Cardiology</institution>
				<institution content-type="orgname">Argentine Federation of Cardiology</institution>
			</aff>
			<aff id="aff6">
				<label>3</label>
				<institution content-type="original">Argentine Society of Cardiology</institution>
				<institution content-type="orgname">Argentine Society of Cardiology</institution>
			</aff>
			<author-notes>
				<corresp id="c2">
					<label>Correspondence</label><bold>:</bold> Julia Janches Quiñones. Research Department, Sanatorio Güemes. Francisco Acuña de Figueroa 1228, 7.° Piso, CP 1180AAX, Buenos Aires, Argentina Tel./Fax 49598200 E-mail: <email>Juliajanches@hotmail.com</email>
				</corresp>
				<fn fn-type="conflict" id="fn3">
					<label>Conflicts of Interest</label>
					<p> None declared. (See the author’s conflict of interests forms on the Web).</p>
				</fn>
			</author-notes>
			<abstract>
				<title>ABSTRACT</title>
				<sec>
					<title>Background:</title>
					<p> Atrial fibrillation (AF) is the most frequent arrhythmic complication in patients with acute coronary syndrome (ACS), and its incidence ranges between 2.3% and 21%.</p>
				</sec>
				<sec>
					<title>Objective: </title>
					<p>To determine the incidence and predictors of <italic>de novo</italic> AF in patients with ST-segment elevation myocardial infarction (STEMI).</p>
				</sec>
				<sec>
					<title>Methods: </title>
					<p>The database of the ARGEN-IAM-ST continuous registry was analyzed. Conventional descriptive statistics were used. To reduce dimensionality and identify those variables associated with the outcome of interest, Machine Learning algorithms were used, and a multivariate logistic regression analysis was performed to identify those factors associated with <italic>de novo</italic> AF. These were included in a final ranking model which was assessed by using the receiver operating characteristic (ROC) curve. A p-value &lt;0.05 was considered statistically significant.</p>
				</sec>
				<sec>
					<title>Results: </title>
					<p>We included 7292 patients with STEMI. A total of 4.3% had <italic>de novo</italic> AF during hospitalization. This group was older (67 vs. 60 years, p &lt;0.001), with higher heart rate and Killip and Kimbal score and lower left ventricular ejection fraction (LVEF) on admission. These patients had a higher incidence of stroke (2.5% vs. 0.8% p = 0.002) and in-hospital death (23.3% vs. 8.2%, p &lt;0.001), but <italic>de novo</italic> AF was not an independent predictor of mortality. The following variables were independent predictors of in-hospital <italic>de novo</italic> AF after STEMI: stratified age (50 to 59 years: OR 2.16, 95% CI 1.11-2.73; 60 to 69 years: OR 1.77, 95% CI 1.07-2.96; 70 to 100 years: OR 3.98, 95% CI 2.60-6.26), Killip and Kimball score (B: OR 1.72 95% CI 1.19-2.46; C: OR 1.09, 95% CI 0.31-2.91, D: OR 2.48, 95% CI 1.60-3.78), tachycardia (OR 2.41, 95% CI 1.74-3.31) and LVEF &lt;35% (OR 1.62, 95% CI 1.74-3.31). The area under the ROC curve (AUC ROC) of the model was 0.73; the sensitivity and specificity were 77% and 62%, respectively.</p>
				</sec>
				<sec>
					<title>Conclusion:</title>
					<p><italic>De novo</italic> AF was a relatively frequent complication. Factors such as age, heart rate, hemodynamic profile on admission and ventricular function were shown to be predictors of <italic>de novo</italic> AF after a myocardial infarction during hospitalization. However, <italic>de novo</italic> AF was not independently associated with in-hospital mortality.</p>
				</sec>
			</abstract>
			<kwd-group xml:lang="en">
				<title>Key words:</title>
				<kwd>Atrial fibrillation</kwd>
				<kwd>ST-elevation myocardial infarction.</kwd>
			</kwd-group>
		</front-stub>
		<body>
			<sec sec-type="intro">
				<title>INTRODUCTION</title>
				<p>Atrial fibrillation (AF) is the most frequent sustained cardiac arrhythmia in adults, and its prevalence has been increasing over the past decades due to aging population and increased survival from other cardiovascular diseases. (<xref ref-type="bibr" rid="B1">1</xref>) It is associated with an increased risk of thromboembolic events, (<xref ref-type="bibr" rid="B2">2</xref>) cognitive impairment, (<xref ref-type="bibr" rid="B3">3</xref>) heart failure, hospitalizations, and death. (<xref ref-type="bibr" rid="B4">4</xref>) </p>
				<p>In turn, it is the most frequent arrhythmic complication in patients with acute coronary syndrome (ACS), and its incidence ranges from 2.3% to 21%. (<xref ref-type="bibr" rid="B5">5</xref>) In Argentina, the incidence of <italic>de novo</italic> AF in this setting is 3.2%, as observed in the ARGEN-IAM-ST registry. (<xref ref-type="bibr" rid="B6">6</xref>) Over the last decades and with the advances in invasive and medical treatment, its incidence has decreased. (<xref ref-type="bibr" rid="B6">6</xref>) Several studies have evaluated the clinical characteristics of patients with <italic>de novo</italic> AF after ACS. The main predictors were advanced age, signs of heart failure, and tachycardia on hospital admission. These predictors have been maintained both in studies performed in the fibrinolytic era and in the present day, when percutaneous treatment is available. (<xref ref-type="bibr" rid="B7">7</xref>, <xref ref-type="bibr" rid="B8">8</xref>)</p>
				<p>In the general population and in patients with ACS, the presence of AF is associated with a worse prognosis. <italic>De novo</italic> AF in the setting of ACS is associated with increased morbidity and mortality. (<xref ref-type="bibr" rid="B9">9</xref>, <xref ref-type="bibr" rid="B10">10</xref>) In turn, several observational studies have shown that patients with coexisting ACS and <italic>de novo</italic> AF are less likely to receive appropriate antithrombotic treatment. (<xref ref-type="bibr" rid="B11">11</xref>, <xref ref-type="bibr" rid="B12">12</xref>) However, there is a lack of studies analyzing the predictors and prognosis of these patients in the setting of invasive and medical treatment, as recommended by the latest guidelines. This study aimed to evaluate the incidence of <italic>de novo</italic> AF during hospitalization for ST-elevation myocardial infarction (STEMI) and to determine the predictors associated with its development.</p>
			</sec>
			<sec sec-type="methods">
				<title>METHODS</title>
				<sec>
					<title>Study design and population</title>
					<p>This is an observational and retrospective study based on the analysis of the continuous registry of ST-segment elevation acute myocardial infarction (ARGEN-IAM-ST), which includes patients with STEMI from numerous centers in Argentina. Its protocol was previously published and has been active since 2015. (<xref ref-type="bibr" rid="B13">13</xref>,<xref ref-type="bibr" rid="B14">14</xref>) The protocol has been registered in ClinicalsTrials.gov under NCT 2458885. The cut-off date for the analysis of this work was May 2024. </p>
				</sec>
				<sec>
					<title>Definitions and outcomes of interest</title>
					<p>Our outcome of interest was <italic>de novo</italic> AF during hospitalization, defined as AF in patients who had an admission electrocardiogram (ECG) showing sinus rhythm and an episode of AF as a complication during their progress. This was modeled as a binary variable. We excluded from this definition those patients with a history of AF and atrial flutter.</p>
				</sec>
				<sec>
					<title>Statistical analysis</title>
					<p>Continuous variables are expressed as mean and standard deviation (SD) or median and interquartile range (IQR), according to their type of distribution. The variables of age and heart rate were analyzed by strata. Qualitative variables are expressed as absolute and relative frequencies. Qualitative variables were compared using the chi-square test or Fisher's exact test, while continuous variables with parametric and nonparametric distribution were compared using Student's t test and the Mann Whitney U test, respectively. </p>
					<p>To reduce dimensionality and identify those variables associated with our outcome of interest, the Boruta Machine Learning algorithm was used. (<xref ref-type="bibr" rid="B15">15</xref>) To ensure that variable selection was stable and reproducible, the algorithm performed up to 50 iterations which allowed a robust assessment of the importance of each predictor in <italic>de novo</italic> AF ranking. In addition, its performance was monitored during the process to verify consistency in feature selection. Multivariate analysis using logistic regression was performed with the most important variables to identify the factors independently associated with <italic>de novo</italic> AF. The models were trained and evaluated on two different databases randomly generated from the general database. The performance of the models and their discrimination ability was evaluated through the generation of receiver operating characteristic (ROC) curves. Since the aim of the model was to maximize sensitivity to identify the greatest number of cases of <italic>de novo</italic> AF, the optimal cut-off point was selected from the ROC curve with the highest possible sensitivity criterion, while maintaining clinically acceptable specificity. The Hosmer Lemeshow test was used to evaluate the goodness of fit of the model. The association between the predictors and the incidence of events was expressed as odds ratio (OR) with their 95% confidence intervals (CI). In addition, a multivariate model was performed to explore <italic>de novo</italic> AF as an independent predictor of mortality. All tests were two-tailed and statistical significance was set at a p-value &lt;0.05.</p>
					<p>The analysis was performed with R Studio, version 1.4.1106 (The R Foundation for Statistical Computing, Vienna, Austria).</p>
				</sec>
				<sec>
					<title>Ethical considerations</title>
					<p>The ethics committee of the Argentine Society of Cardiology approved the protocol of the Argen IAM-ST registry.</p>
				</sec>
			</sec>
			<sec sec-type="results">
				<title>RESULTS</title>
				<sec>
					<title>Baseline characteristics of the population</title>
					<p>We included a total of 7292 patients with STEMI and evidence of sinus rhythm on admission ECG, of which 79% were male, and had a median (IQR) age of 61 (53-69) years. <xref ref-type="table" rid="t3">Table 1</xref> shows the baseline characteristics.</p>
					<p>
						<table-wrap id="t3">
							<label>Table 1</label>
							<caption>
								<title>Baseline clinical characteristics of participants with and without de <italic>novo</italic> AF</title>
							</caption>
							<table frame="hsides" rules="groups">
								<colgroup>
									<col/>
									<col/>
									<col/>
									<col/>
									<col/>
								</colgroup>
								<thead>
									<tr style="border: 0; background-color:#ab0534;color:#ffffff;">
										<th align="left"> </th>
										<th align="center">Global</th>
										<th align="center">Without <italic>de novo</italic> AF</th>
										<th align="center">With <italic>de novo</italic> AF</th>
										<th align="center">p</th>
									</tr>
								</thead>
								<tbody>
									<tr style="background-color: #e3aea9;">
										<td align="left"> n</td>
										<td align="center">7292</td>
										<td align="center">6974</td>
										<td align="center">318</td>
										<td align="right"> </td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Male gender, n (%)</td>
										<td align="center">5754 (79)</td>
										<td align="center">5512 (79)</td>
										<td align="center">248 (78)</td>
										<td align="center"> 0.705</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Age, years, median (IQR)</td>
										<td align="center">61 (53-69]</td>
										<td align="center">60 (53-68)</td>
										<td align="center">67(60-77)</td>
										<td align="center">&lt;0.001</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">BMI, kg/m<sup>2</sup>, median (IQR)</td>
										<td align="center">27.65 (25.47-30.61)</td>
										<td align="center">27.68 (25.51-30.76)</td>
										<td align="center">27.41 (25.28-29.97)</td>
										<td align="center">0.041</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">DM, n (%)</td>
										<td align="center">1980 (27.2)</td>
										<td align="center">1900 (27.2)</td>
										<td align="center">80 (25.2)</td>
										<td align="center">0.451</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Smoking, n (%)</td>
										<td align="center">591 (8.1)</td>
										<td align="center">563 ( 8.1)</td>
										<td align="center">28 ( 8.8)</td>
										<td align="center">0.717</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">DLP, n (%)</td>
										<td align="center">2662 (36.5)</td>
										<td align="center">2553 (36.6)</td>
										<td align="center">109 (34.3)</td>
										<td align="center">0.433</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">HT, n (%)</td>
										<td align="center">3870 (53.1)</td>
										<td align="center">3661 (52.5)</td>
										<td align="center">209 (65.7)</td>
										<td align="center">&lt;0.001</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Previous coronary artery disease, n (%)</td>
										<td align="center">897 (12.3)</td>
										<td align="center">846 (12.1)</td>
										<td align="center">51 (16.0)</td>
										<td align="center">0.047</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Beta-blockers , n (%)</td>
										<td align="center">3635 (50.0)</td>
										<td align="center">3519 (50.5)</td>
										<td align="center">120 (37.7)</td>
										<td align="center">&lt;0.001</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">ACEIs, n (%)</td>
										<td align="center">3301 (45.4)</td>
										<td align="center">3178 (45.6)</td>
										<td align="center">129 (40.6)</td>
										<td align="center">0.090</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Glycemia, mg/dL, median (IQR)</td>
										<td align="center">135 (113-179)</td>
										<td align="center">134 (113-177)</td>
										<td align="center">153 (124-212.50)</td>
										<td align="center">&lt;0.001</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Creatinine, mg/dL, median (IQR)</td>
										<td align="center">0.97 (0.80-1.18)</td>
										<td align="center">0.97 (0.80-1.17)</td>
										<td align="center">1.08 (0.90-1.40)</td>
										<td align="center">&lt;0.001</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Reason for PCI, n (%)</td>
										<td align="center"> </td>
										<td align="center"> </td>
										<td align="center"> </td>
										<td align="center">0.949</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Primary </td>
										<td align="center">5003 (91.1)</td>
										<td align="center">4887 (70.1)</td>
										<td align="center">207 (65.1)</td>
										<td align="center"> </td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Pharmacoinvasive</td>
										<td align="center">273 (5.0)</td>
										<td align="center">646 (9.3)</td>
										<td align="center">37 (11.6)</td>
										<td align="center"> </td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Rescue</td>
										<td align="center">154 (2.8)</td>
										<td align="center">976 (14.0)</td>
										<td align="center">45 (14.2)</td>
										<td align="center"> </td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Elective</td>
										<td align="center">59 (1.1)</td>
										<td align="center">465 (6.7)</td>
										<td align="center">29 (9.1)</td>
										<td align="center"> </td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">SBP, mm Hg, mean (SD)</td>
										<td align="center">131 (29)</td>
										<td align="center">132 (29)</td>
										<td align="center">121 (29)</td>
										<td align="center">&lt;0.001</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">HR, bpm, mean (SD)</td>
										<td align="center">80 (19)</td>
										<td align="center">80 (18)</td>
										<td align="center">86 (26)</td>
										<td align="center">&lt;0.001</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Killip and Kimball, n (%)</td>
										<td align="center"> </td>
										<td align="center"> </td>
										<td align="center"> </td>
										<td align="center">&lt;0.001</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">A</td>
										<td align="center">5485 (77.0)</td>
										<td align="center">5456 (78.2)</td>
										<td align="center">153 (48.1)</td>
										<td align="center"> </td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">B</td>
										<td align="center">1024 (14.4)</td>
										<td align="center">955 (13.7)</td>
										<td align="center">90 (28.3)</td>
										<td align="center"> </td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">C</td>
										<td align="center">100 (1.4)</td>
										<td align="center">95 (1.4)</td>
										<td align="center">8 (2.5)</td>
										<td align="center"> </td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">D</td>
										<td align="center">516 (7.2)</td>
										<td align="center">468 (6.7)</td>
										<td align="center">67 (21.1)</td>
										<td align="center"> </td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Door-to-balloon time, min, median (IQR)</td>
										<td align="center">84 (47-147]</td>
										<td align="center">91(50. 175]</td>
										<td align="center">92. (51.25- 209.75]</td>
										<td align="center">0.439</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Time window, min, median (IQR)</td>
										<td align="center">230 (135-440)</td>
										<td align="center">252.50 (146- 510)</td>
										<td align="center">289.50 (162.25- 612.25)</td>
										<td align="center">0.019</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Multi-vessel PCI in initial procedure, n (%)</td>
										<td align="center">351 (6.4)</td>
										<td align="center">360 (5.2)</td>
										<td align="center">26 (8.2)</td>
										<td align="center">0.026</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">LVSF, n (%)</td>
										<td align="center"> </td>
										<td align="center"> </td>
										<td align="center"> </td>
										<td align="center">&lt;0.001</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Normal</td>
										<td align="center">2397 (37.4)</td>
										<td align="center">2660 (38.1)</td>
										<td align="center">75 (23.6)</td>
										<td align="center"> </td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Mild impairment</td>
										<td align="center">1842 (28.7)</td>
										<td align="center">1994 (28.6)</td>
										<td align="center">58 (18.2)</td>
										<td align="center"> </td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Moderate impairment</td>
										<td align="center">1397 (21.8)</td>
										<td align="center">1466 (21.0)</td>
										<td align="center">93 (29.2)</td>
										<td align="center"> </td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Severe impairment </td>
										<td align="center">774 (12.1)</td>
										<td align="center">854 (12.2)</td>
										<td align="center">92 (28.9)</td>
										<td align="center"> </td>
									</tr>
								</tbody>
							</table>
							<table-wrap-foot>
								<fn id="TFN3">
									<p>ACEIs: angiotensin-converting enzyme inhibitors; AF: atrial fibrillation; BMI: body mass index; bpm: beats per minute; DLP: dyslipidemia; DM: diabetes mellitus; HR: heart rate; HT: hypertension; IQR: interquartile range; LVSF: left ventricular systolic function; PCI: percutaneous coronary intervention;SBP: systolic blood pressure; SD: standard deviation </p>
								</fn>
							</table-wrap-foot>
						</table-wrap>
					</p>
					<p>We identified that 4.3% of the sample patients had <italic>de novo</italic> AF during hospitalization. These patients were older than those with no <italic>de novo</italic> AF (median age 67 vs. 60 years; p &lt;0.001). We found no differences between the groups related to body mass index (BMI), diabetes mellitus and dyslipidemia. However, 53.1% had arterial hypertension (HT), and the prevalence was higher in the group of patients who developed AF during hospitalization (65.7% vs. 52.5%; p &lt;0.001). In turn, the history of coronary artery disease -which was present in 12.3% of the total sample- was also more frequent in the group with <italic>de novo</italic> AF (16% vs. 12.1%; p = 0.047). </p>
					<p>Regarding reperfusion strategies in all patients, primary angioplasty was performed in 91%, a pharmacoinvasive strategy in 5%, rescue angioplasty in 2.8%, and elective angioplasty in 1.1%, with no significant differences between the study groups. However, multi-vessel angioplasty was performed in the initial procedure in a higher proportion of patients who developed AF during hospitalization. There were no significant differences in the treatment of the culprit vessel for AMI.</p>
					<p>Regarding treatment with beta-blockers and angiotensin-converting enzyme inhibitors on admission, we found a lower use in patients with <italic>de novo</italic> AF, that is, 37.7% vs 50.5% (p = 0.001) and 40.6% vs.45.6% (p =0.090), respectively.</p>
					<p>On hospital admission, those patients who developed AF had a higher heart rate (86 bpm vs. 80 bpm; p &lt;0.001). Regarding laboratory tests, they had higher glycemia values, with a median (IQR) of 153 mg/dl (124-212) vs. 134 mg/dL (113-177), p &lt;0.001, and higher creatinine values: 1.08 mg/dL (0.90-1.40) vs. 0.97 mg/dL (0.8-1.17), p &lt;0.001. </p>
					<p>This group of patients also had longer total ischemia time (medians 289 min vs. 252 min; p = 0.019), a more severe Killip and Kimball score (p &lt;0.001) and lower left ventricular ejection fraction (LVEF) (p &lt;0.001). </p>
				</sec>
				<sec>
					<title>In-hospital events</title>
					<p>The presence of <italic>de novo</italic> AF was associated with a higher incidence of ischemic stroke (2.5% vs. 0.8%; p = 0.002) and more days of hospitalization (medians 6 vs. 4 days; p &lt;0.001). In-hospital all-cause death was also higher in the <italic>de novo</italic> AF group (23.3% vs. 8.2%; p &lt;0.001) (<xref ref-type="table" rid="t4">Table 2</xref>).</p>
					<p>
						<table-wrap id="t4">
							<label>Table 2</label>
							<caption>
								<title>In-hospital events of participants with and without de <italic>novo</italic> AF.</title>
							</caption>
							<table frame="hsides" rules="groups">
								<colgroup>
									<col/>
									<col/>
									<col/>
									<col/>
									<col/>
								</colgroup>
								<thead>
									<tr style="background-color: #e3aea9;">
										<th align="left"> </th>
										<th align="center">Global</th>
										<th align="center">Without <italic>de novo</italic> AF</th>
										<th align="center">With <italic>de novo</italic> AF</th>
										<th align="center">p</th>
									</tr>
								</thead>
								<tbody>
									<tr style="border: 0; background-color:#ab0534;color:#ffffff;">
										<td align="left"> n</td>
										<td align="center">7292</td>
										<td align="center">6974</td>
										<td align="center">318</td>
										<td align="right"> </td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Reinfarction, n (%)</td>
										<td align="center"> 123 (1.7)</td>
										<td align="center"> 113 (1.6)</td>
										<td align="center"> 10 (3.1)</td>
										<td align="center"> 0.066</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Stroke, n (%)</td>
										<td align="center"> 61 (0.8) </td>
										<td align="center"> 53 (0.8) </td>
										<td align="center"> 8 (2.5) </td>
										<td align="center"> 0.002</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">Cardiogenic shock, n (%)</td>
										<td align="center"> 682 (9.4)</td>
										<td align="center"> 576 (8.3)</td>
										<td align="center"> 106 (33.3)</td>
										<td align="center"> &lt;0.001</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">HF, n (%)</td>
										<td align="center"> 967 (13.3)</td>
										<td align="center"> 818 (11.7)</td>
										<td align="center"> 149 (46.9)</td>
										<td align="center"> &lt;0.001</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">In-hospital death, n (%)</td>
										<td align="center">591 (8.1)</td>
										<td align="center">563 (8.1)</td>
										<td align="center">28 (8.8)</td>
										<td align="center">0.717</td>
									</tr>
									<tr style="background-color: #e3aea9;">
										<td align="left">LOS, days, median (IQR)</td>
										<td align="center"> 4 (3-6)</td>
										<td align="center"> 4 [3-6]</td>
										<td align="center"> 6 [4-11]</td>
										<td align="center">&lt;0.001</td>
									</tr>
								</tbody>
							</table>
							<table-wrap-foot>
								<fn id="TFN4">
									<p>AF, atrial fibrillation; HF, heart failure; IQR, interquartile range; LOS: length of stay</p>
								</fn>
							</table-wrap-foot>
						</table-wrap>
					</p>
				</sec>
				<sec>
					<title>Selection of important variables </title>
					<p>Using the Boruta algorithm, an automated selection was performed to identify the variables with the greatest importance in the prediction of <italic>de novo</italic> AF. In the analysis, the Killip and Kimball, heart rate and LVEF variables were identified as the most important, followed by gender, age, dyslipidemia, and creatinine. <xref ref-type="fig" rid="f5">Figure 1</xref> shows the means of importance of each variable in the ranking. Subsequently, these variables were included in the multivariate logistic regression model to evaluate their association with the outcome. </p>
					<p>
						<fig id="f5">
							<label>Fig. 1.</label>
							<caption>
								<title>Variables with the greatest importance in the prediction of <italic>de novo</italic> AF. </title>
								<p>AF: atrial fibrillation; CAD: coronary artery disease; LVEF: left ventricular ejection fraction; MV: multiple vessels; PCI: percutaneous coronary inter- vention; proc: procedure; time window: time in minutes from symptom onset to start of infusion in the case of fibrinolytics or to balloon inflation in the case of PCI</p>
							</caption>
							<graphic xlink:href="1850-3748-rac-93-02-99-gf5.jpg"/>
						</fig>
					</p>
				</sec>
				<sec>
					<title>Multivariate analysis: Independent predictors of <italic>de novo</italic> AF</title>
					<p>The greatest weight variables associated with <italic>de novo</italic> AF were included in a multivariate logistic regression model. The stratified age (50 to 59 years, 60 to 69 years, and 70 to 100 years) was independently associated with the incidence of <italic>de novo</italic> AF (OR 1.72, 95% CI 1.11-2.73; OR 1.77, 95% CI 1.07-2.96; OR 3.98, 95% CI 2.60-6.25, respectively). Clinical presentation according to Killip and Kimball score (B: OR 1.72, 95% CI 1.19-2.46; C: OR 1.09, 95% CI 0.315-2.90; D: OR 2.48, 95% CI 1.60-3.78), tachycardia (OR 2.41, 95% CI 1.74-3.31) and impaired LVEF (&lt;35%) (OR 1.62, 95% CI 1.04-2.50) were also independent predictors (<xref ref-type="fig" rid="f6">Figure 2</xref>). To evaluate the performance of the model, a ROC curve was constructed and the area under the curve (AUC) was 0.733 (95% CI 0.698-0.769). The optimal cut-off point was determined at 0.10 to maximize sensitivity. According to this threshold, the model correctly identified 77% of patients with <italic>de novo</italic> AF (sensitivity) and 62% of patients without <italic>de novo</italic> AF (specificity)<bold>.</bold> This cut-off point represents the threshold where the balance between sensitivity and specificity is clinically most appropriate for the detection of <italic>de novo</italic> AF (<xref ref-type="fig" rid="f7">Figure 3</xref>). The goodness of fit of the model, assessed by the Hosmer-Lemeshow test, was good (χ² = 5.33, p = 0.618).</p>
					<p>
						<fig id="f6">
							<label>Fig. 2</label>
							<caption>
								<title>Predictors of <italic>de novo</italic> AF </title>
								<p>AF: atrial fibrillation; LVEF: left ventricular ejection fraction</p>
							</caption>
							<graphic xlink:href="1850-3748-rac-93-02-99-gf6.jpg"/>
						</fig>
					</p>
					<p>
						<fig id="f7">
							<label>Fig. 3</label>
							<caption>
								<title>ROC curve of the <italic>de novo</italic> AF predictive model </title>
								<p>AF: atrial fibrillation; AUC: area under curve; ROC: receiver operating characteristic; S: sensitivity; Sp: specificity</p>
							</caption>
							<graphic xlink:href="1850-3748-rac-93-02-99-gf7.jpg"/>
						</fig>
					</p>
				</sec>
				<sec>
					<title><bold>Multivariate analysis: <italic>de novo</italic> AF as an independent predictor of mortality</bold></title>
					<p><italic>De novo</italic> AF was included with the main variables related to in-hospital mortality in a multivariate model. We observed that <italic>de novo</italic> AF did not behave as an independent predictor of in-hospital mortality (OR 0.79, 95% CI 0.41-1.50) (<xref ref-type="fig" rid="f8">Figure 4</xref>).</p>
					<p>
						<fig id="f8">
							<label>Fig. 4</label>
							<caption>
								<title>Predictors of in-hospital mortality </title>
								<p>AF: atrial fibrillation</p>
							</caption>
							<graphic xlink:href="1850-3748-rac-93-02-99-gf8.jpg"/>
						</fig>
					</p>
				</sec>
			</sec>
			<sec sec-type="discussion">
				<title>DISCUSSION </title>
				<p>We present data on the incidence of <italic>de novo</italic> AF during hospitalization for STEMI from the ARGEN-IAM-ST registry. On this occasion, cases with AF on admission ECG or with history of AF were excluded in order to evaluate the consequences of this event after AMI. The incidence of <italic>de novo</italic> AF was 4.3%, and the findings suggest an association with a greater number of in-hospital events and a longer hospital stay. In addition, certain factors such as age, heart failure assessed by the Killip and Kimball score, tachycardia, and impaired LVEF were shown to be independent predictors of <italic>de novo</italic> AF during hospitalization. These predictors were included in a ranking model to predict <italic>de novo</italic> AF, which showed an AUC of 0.733 (95% CI 0.698-0.769)<italic>.</italic></p>
				<p>AF and ACS are two common heart diseases and, over the years, multiple studies have been performed to analyze the relationship between them. The risk of <italic>de novo</italic> AF increases by 60-77% in patients with AMI. (<xref ref-type="bibr" rid="B16">16</xref>) In the fibrinolytic era, the randomized GUSTO-I (1997) and GUSTO-III (2000) studies compared different fibrinolytic regimens in patients with STEMI, and highlighted a 7.9% and 6.5% incidence of <italic>de novo</italic> AF after ACS, respectively. (8, 17) In addition, OACIS, a prospective observational study published in 2003, analyzed patients with AMI (with and without ST-segment elevation) who underwent coronary angioplasty within 24 hours and found that the incidence of <italic>de novo</italic> AF was 7.7%. (<xref ref-type="bibr" rid="B18">18</xref>) Regarding national results, the incidence of in-hospital <italic>de novo</italic> AF in patients with AMI and unstable angina was 4.3% and 7.7%, respectively, according to data from the Buenos Aires I registry, which included patients with non-ST-elevation acute coronary syndrome (NSTE-ACS). (<xref ref-type="bibr" rid="B19">19</xref>) Similarly, a previous publication from the ARGEN-IAM-ST registry showed that the incidence of <italic>de novo</italic> AF was 3.2%, and the predictor factors were advanced age, history of HT and previous coronary artery disease. (<xref ref-type="bibr" rid="B6">6</xref>) There are definitely no randomized studies comparing the incidence of <italic>de novo</italic> AF in patients with STEMI treated with fibrinolytics versus primary angioplasty, and the differences in the populations and methods used in the published studies preclude a correct assessment of the incidence of this complication and whether the type of revascularization has an impact on it. </p>
				<p>In our cohort, age acted as an independent predictor of <italic>de novo</italic> AF, with the higher impact observed specifically between the ages of 70 and 100 years, with an OR of 3.98. As AF outside the setting of ACS, age was closely related to the incidence of this arrhythmia. In one of the largest studies including only patients aged ≥65 years from the Cooperative Cardiovascular Project database published in 2000, (<xref ref-type="bibr" rid="B11">11</xref>) the rate of <italic>de novo</italic> AF after ACS was 22%, significantly higher than in studies including patients of all ages. In addition, the 2009 review by Schmitt et al., found that all studies published between 1992 and 2007 identified older age as an independent predictor of <italic>de novo</italic> AF after ACS. (<xref ref-type="bibr" rid="B20">20</xref>)</p>
				<p>Although AF is the most frequent supraventricular arrhythmia in the general population, its incidence is significantly higher in patients with heart failure (HF). These two conditions are closely related to each other, and each perpetuates the presence of the other. (<xref ref-type="bibr" rid="B21">21</xref>) Our analysis showed that HF, as assessed by the Killip and Kimball score, was independently associated with <italic>de novo</italic> AF<italic>,</italic> as showed in the above mentioned GUSTO-I and III studies. Of note, a subanalysis of the international GRACE study, which included more than 21 000 patients with ACS and classified them according to the presence of <italic>de novo</italic> AF, previous AF, and no AF, identified a Killip score ≥2 as an independent predictor of <italic>de novo</italic> AF<italic>.</italic> (<xref ref-type="bibr" rid="B22">22</xref>) Similarly, tachycardia, probably secondary to HF, was also a predictor of <italic>de novo</italic> AF in our study and in the previously mentioned study. These results translate the impact of hemodynamic status within the pathophysiological mechanisms of AF in the setting of ACS and indicate that patients with altered hemodynamic status (HF, tachycardia, and/or hypotension) are at higher risk of AF.</p>
				<p>In parallel, severely impaired LVEF (&lt;35%) also functioned as an independent predictor of <italic>de novo</italic> AF in our analysis. Although the association between ventricular dysfunction and clinical presentation on admission (as reflected by the Killip and Kimball score and heart rate) is clear, other studies have not shown this variable to be an independent predictor of <italic>de no</italic>vo AF. </p>
			</sec>
			<sec>
				<title>LIMITATIONS</title>
				<p>The registry ARGEN-IAM-ST is a voluntary participation registry with no audit strategy. Although a multivariate regression analysis was performed, we cannot completely exclude the possibility that unconsidered variables may have altered the results. Furthermore, although this is a multicenter study, it only represents the reality of the participating centers. Finally, it is not possible to determine when AF occurred during hospitalization, and thus the temporal relationship cannot be studied.</p>
			</sec>
			<sec sec-type="conclusions">
				<title>CONCLUSION</title>
				<p>In this cohort of patients from the ARGEN-IAM-ST registry, <italic>de novo</italic> AF was a relatively frequent complication. Factors such as age, heart rate, hemodynamic profile on admission, and ventricular function were shown to be predictors of <italic>de novo</italic> AF after an AMI during hospitalization. However, <italic>de novo</italic> AF was not independently associated with in-hospital mortality.</p>
			</sec>
		</body>
	</sub-article>-->
</article>