None; None

Resúmenes

Justificación y objetivo: diversos estudios han demostrado la eficacia de los desfibriladores automáticos implantables en la prevención de la muerte súbita cardiaca. La aplicación de dicha evidencia debe ser evaluada mediante registros. El objetivo de este estudio fue describir las principales características epidemiológicas y clínicas y las complicaciones de los pacientes a quienes se les implanta un desfibrilador automático implantable en un hospital de tercer nivel en Costa Rica. Métodos: estudio observacional de cohorte, retrospectivo, que incluyó la totalidad de pacientes a quienes se les implantó un desfibrilador automático implantable en el hospital “Dr. Rafael Ángel Calderón Guardia” entre 2007 y 2011. Resultados: se incluyó 23 pacientes. La edad media fue de 55 ± 18 años. La cardiopatía isquémica fue la etiología más frecuente (10 pacientes). Veinte pacientes estaban en clase funcional I o II; la fracción de eyección media fue 0,38 ± 0,17. En los 18 pacientes el desfibrilador automático se implantó por prevención secundaria. Cinco pacientes presentaron una complicación temprana, todos ellos con dispositivos bicamerales: 2 hematomas menores, una disección del seno coronario, un desplazamiento del electrodo atrial derecho y un ictus cardioembólico. Hubo un total de 101 terapias (en 8 pacientes), de las cuales 94 fueron apropiadas (en 5 pacientes) y 7 inapropiadas (en 3 pacientes); dos de estos últimos habían tenido episodios previos de fibrilación atrial. Conclusión: este registro muestra que la mayoría de los implantes de desfibriladores automáticos se realizan por prevención secundaria, con una alta tasa de terapias adecuadas y una baja tasa de terapias inadecuadas y de complicaciones; además, permite evaluar las indicaciones y las complicaciones asociadas con esta terapia. este registro muestra que la mayoría de los implantes de desfibriladores automáticos se realizan por prevención secundaria, con una alta tasa de terapias adecuadas y una baja tasa de terapias inadecuadas y de complicaciones; además, permite evaluar las indicaciones y las complicaciones asociadas con esta terapia.

desfibriladores implantables; muerte súbita; arritmias; complicaciones

Aim: Several studies have demonstrated the efficacy of implantable cardioverter-defibrillators in the prevention of sudden cardiac death. The validation of this evidence has to be assessed through various registries. The objective of this study was to describe the main epidemiological and clinical characteristics of patients who were referred to a tertiary hospital in Costa Rica to be treated with a cardioverter-defibrillators implantable; as well as the associated problems and complications. Methods: A retrospective observational cohort study, which included all patients who were treated with a cardioverter-defibrillator implantable in the “Dr. Rafael A. Calderón Guardia” hospital between 2007 and 2011. Results: Twenty three patients were included. The mean age was 55 ± 18 years. Ischemic heart disease was the most frequent etiology (10 patients). Twenty patients had functional class I or II and the mean ejection fraction was 0.38 ± 0.17. In 18 patients, the cardioverter-defibrillator was implanted for secondary prevention. Five patients had an early complication; all of them had dual-chamber devices: 2 minor hematomas, 1 coronary sinus dissection, 1 right atrial lead displacement, and 1 cardio embolic stroke. From a total of 101 therapies (in 8 patients), 94 were appropriate (in 5 patients) and 7 were inappropriate (in 3 patients); 2 of the latter 3 patients had a history of atrial fibrillation episodes. Conclusion: This registry shows that the majority of implantable cardioverter-defibrillators implantations are performed as a secondary prevention, with a high rate of adequate therapies and a low rate of inadequate ones. The registry allowed an assessment of the indications and complications of this device therapy.This registry shows that the majority of implantable cardioverter-defibrillators implantations are performed as a secondary prevention, with a high rate of adequate therapies and a low rate of inadequate ones. The registry allowed an assessment of the indications and complications of this device therapy.

Implantable defibrillators; sudden death; arrhythmias

Aim: Several studies have demonstrated the efficacy of implantable cardioverter-defibrillators in the prevention of sudden cardiac death. The validation of this evidence has to be assessed through various registries. The objective of this study was to describe the main epidemiological and clinical characteristics of patients who were referred to a tertiary hospital in Costa Rica to be treated with a cardioverter-defibrillators implantable; as well as the associated problems and complications. Methods: A retrospective observational cohort study, which included all patients who were treated with a cardioverter-defibrillator implantable in the “Dr. Rafael A. Calderón Guardia” hospital between 2007 and 2011. Results: Twenty three patients were included. The mean age was 55 ± 18 years. Ischemic heart disease was the most frequent etiology (10 patients). Twenty patients had functional class I or II and the mean ejection fraction was 0.38 ± 0.17. In 18 patients, the cardioverter-defibrillator was implanted for secondary prevention. Five patients had an early complication; all of them had dual-chamber devices: 2 minor hematomas, 1 coronary sinus dissection, 1 right atrial lead displacement, and 1 cardio embolic stroke. From a total of 101 therapies (in 8 patients), 94 were appropriate (in 5 patients) and 7 were inappropriate (in 3 patients); 2 of the latter 3 patients had a history of atrial fibrillation episodes. Conclusion: This registry shows that the majority of implantable cardioverter-defibrillators implantations are performed as a secondary prevention, with a high rate of adequate therapies and a low rate of inadequate ones. The registry allowed an assessment of the indications and complications of this device therapy.

Implantable defibrillators; sudden death; arrhythmias

Costa Rica: report from the registry of patients with implantable cardioverter-defibrillators, 2007-2011

Hugo Arguedas-Jiménez,¹*Oswaldo Gutiérrez-Sotelo²*

*^{Dirección para correspondencia:}

Justificación y objetivo: diversos estudios han demostrado la eficacia de los desfibriladores automáticos implantables en la prevención de la muerte súbita cardiaca. La aplicación de dicha evidencia debe ser evaluada mediante registros. El objetivo de este estudio fue describir las principales características epidemiológicas y clínicas y las complicaciones de los pacientes a quienes se les implanta un desfibrilador automático implantable en un hospital de tercer nivel en Costa Rica.

Métodos: estudio observacional de cohorte, retrospectivo, que incluyó la totalidad de pacientes a quienes se les implantó un desfibrilador automático implantable en el hospital “Dr. Rafael Ángel Calderón Guardia” entre 2007 y 2011.

Resultados: se incluyó 23 pacientes. La edad media fue de 55 ± 18 años. La cardiopatía isquémica fue la etiología más frecuente (10 pacientes). Veinte pacientes estaban en clase funcional I o II; la fracción de eyección media fue 0,38 ± 0,17. En los 18 pacientes el desfibrilador automático se implantó por prevención secundaria. Cinco pacientes presentaron una complicación temprana, todos ellos con dispositivos bicamerales: 2 hematomas menores, una disección del seno coronario, un desplazamiento del electrodo atrial derecho y un ictus cardioembólico. Hubo un total de 101 terapias (en 8 pacientes), de las cuales 94 fueron apropiadas (en 5 pacientes) y 7 inapropiadas (en 3 pacientes); dos de estos últimos habían tenido episodios previos de fibrilación atrial.

Conclusión: este registro muestra que la mayoría de los implantes de desfibriladores automáticos se realizan por prevención secundaria, con una alta tasa de terapias adecuadas y una baja tasa de terapias inadecuadas y de complicaciones; además, permite evaluar las indicaciones y las complicaciones asociadas con esta terapia.

Descriptores: desfibriladores implantables, muerte súbita, arritmias, complicaciones

Aim: Several studies have demonstrated the efficacy of implantable cardioverter-defibrillators in the prevention of sudden cardiac death. The validation of this evidence has to be assessed through various registries. The objective of this study was to describe the main epidemiological and clinical characteristics of patients who were referred to a tertiary hospital in Costa Rica to be treated with a cardioverter-defibrillators implantable; as well as the associated problems and complications.

Methods: A retrospective observational cohort study, which included all patients who were treated with a cardioverter-defibrillator implantable in the “Dr. Rafael A. Calderón Guardia” hospital between 2007 and 2011.

Results: Twenty three patients were included. The mean age was 55 ± 18 years. Ischemic heart disease was the most frequent etiology (10 patients). Twenty patients had functional class I or II and the mean ejection fraction was 0.38 ± 0.17. In 18 patients, the cardioverter-defibrillator was implanted for secondary prevention. Five patients had an early complication; all of them had dual-chamber devices: 2 minor hematomas, 1 coronary sinus dissection, 1 right atrial lead displacement, and 1 cardio embolic stroke. From a total of 101 therapies (in 8 patients), 94 were appropriate (in 5 patients) and 7 were inappropriate (in 3 patients); 2 of the latter 3 patients had a history of atrial fibrillation episodes.

Conclusion: This registry shows that the majority of implantable cardioverter-defibrillators implantations are performed as a secondary prevention, with a high rate of adequate therapies and a low rate of inadequate ones. The registry allowed an assessment of the indications and complications of this device therapy.

Key words: Implantable defibrillators, sudden death, arrhythmias.

^1-5 El riesgo de muerte de alguien que ha tenido un episodio abortado de MS es cercano al 95%; la mitad de los sobrevivientes será rehospitalizado en menos de un año y un 40% morirá en los siguientes 2 años desde el evento.^2-4 El riesgo de MS se incrementa en forma exponencial cuando la fracción de eyección (FE) es menor de 0,3.³ La clase funcional también ha demostrado ser un predictor independiente de riesgo de MS,^4,5 especialmente en pacientes con clase funcional IV, pero solo representa un tercio del total de estas muertes, dado que los restantes 2 tercios ocurren en pacientes con síntomas compensados de falla cardiaca y clase funcional II.^6,7 La identificación de las poblaciones en riesgo de MS ha tenido poco efecto en la disminución de su incidencia acumulada, ya que la mayor parte ocurre en personas sin factores de riesgo identificables, es decir, población “conocida sana”.

⁸^-10 y su superioridad con respecto al tratamiento farmacológico. Se define como prevención secundaria aquellas medidas que se aplican luego de un episodio de MS abortado o de un episodio de taquicardia ventricular (TV) sostenida, con o sin compromiso hemodinámico. Prevención primaria se refiere a la que se aplica sin haber ocurrido ninguno de dichos eventos. Se han establecido guías de manejo por consenso internacional⁹ y, consecuentemente, se ha producido un aumento en el número global de implantes, lo que obliga a evaluar la evidencia aplicada a la realidad particular de cada población y centro. La única manera de lograrlo es mediante la realización de encuestas y registros que permitan comparar los resultados obtenidos con otros centros y conocer las poblaciones en las que se implantan DAI.^10-14 El objetivo de este estudio fue describir las principales características epidemiológicas y clínicas en el momento del implante, así como conocer las complicaciones inmediatas y tardías de la población con un DAI, tanto por prevención primaria como secundaria, en un hospital de tercer nivel de Costa Rica.

Microfilm. Se analizaron las características demográficas, historia cardiovascular, antecedentes de arritmias supraventriculares y ventriculares, características del implante y la programación de los dispositivos, complicaciones intraoperatorias y a largo plazo, así como la ocurrencia de eventos y terapias suministradas por los dispositivos. Se corroboraron los datos demográficos y fechas de nacimiento y de defunción, con la base de datos del Registro Civil de Costa Rica. Los registros de defunción se revisaron por última vez el 6 de enero de 2012. La información relacionada con los eventos almacenados en la memoria de los dispositivos se basó principalmente en los expedientes que confeccionan las empresas proveedoras, y a los cuales se les incluye un reporte de seguimiento tras cada cita de control.

Figura 1. Se consideró que una terapia fue apropiada cuando el dispositivo detectó adecuadamente un episodio de arritmia ventricular y administró una terapia programada, mientras que la terapia inapropiada fue aquella que se produjo por inadecuada discriminación de un episodio arrítmico supraventricular, o por sobredetección de señales extracardiacas como miopotenciales o interferencia electromagnética. Se definió “tormenta eléctrica” como la ocurrencia de 3 o más episodios de TV o de FV sostenidos dentro en un periodo de 24 horas, cada uno separado del anterior por, al menos, 5 minutos de intervalo libre de arritmia ventricular. Se definió como complicación temprana la ocurrida en los primeros 30 días desde el implante del dispositivo, y la tardía, la que ocurrió luego de ese periodo. Una complicación menor fue aquella que no ameritó reintervención, hospitalización, ni implicó un riesgo para la vida del paciente.

Figura 1

^{Cuadro 1}).

Figura 2). La mayoría de pacientes se encontraba en clase funcional I o II al momento del implante (20 pacientes). Solamente 2 pacientes estaban en clase funcional III y uno estaba en clase IV. La mayoría de la población tenía deterioro moderado o severo de la FE, con una media de 0,38 ± 0,17, y en cerca de una tercera parte de la población era < 0,25. Al momento del implante, 17 pacientes se encontraban en ritmo sinusal y 5 en fibrilación atrial (FA). Nueve pacientes tuvieron un evento previo de FA. Cinco pacientes tenían bloqueo de rama izquierda del haz de His, 3 de rama derecha, 2 tenían un bloqueo atrioventricular de primer grado y 1 tenía enfermedad del nodo sinusal.

Figura 2

Figura 2).

^{Cuadro 1}). A 15 pacientes de prevención secundaria se les medicaba con amiodarona, mientras que solamente 1 de prevención primaria la tomaba.

versus secundaria, no se encontró diferencias significativas con respecto a la edad, predominio de género, FE, clase funcional, antecedentes clínicos o uso de medicamentos. Las únicas diferencias significativas entre ambos grupos fueron un mayor uso de amiodarona en los pacientes en prevención secundaria (ya mencionado), y la duración del intervalo QRS en el grupo en prevención secundaria (p <0,05, ^{Cuadro 2}).

ictus cardioembólico dos días después, con compromiso del territorio de la arteria cerebral media izquierda, que produjo secuelas motora y del lenguaje (^{Cuadro 3}).

^{Cuadro 3}).

Figura 3).

Figura 3

Figura 4). Cinco pacientes presentaron una tormenta eléctrica; se trataba de cuatro pacientes de prevención secundaria: 3 con cardiopatía isquémica y 1 con MCDNI. Los 4 pacientes no han vuelto a recurrir, tras el ajuste de la medicación antiarrítmica y la reprogramación de las zonas de terapia con marcapasos antitaquicardia. El último caso de tormenta fue un hombre con MCDNI en clase funcional IV y FE=0,15, a quien se le implantó un DAI con resindronización como opción de salvataje ante lo avanzado de su enfermedad. Desarrolló TV y FV recurrentes y tuvo terapias apropiadas del DAI; sin embargo, falleció tres días después, por falla cardiaca terminal y disociación electromecánica.

Figura 4

¹¹ A pesar que la edad promedio parece ser menor en este estudio con respecto a otros reportes, su variación osciló en el rango descrito en la bibliografía.^12,13 También las cardiopatías subyacentes se distribuyeron en forma similar, siendo la enfermedad isquémica coronaria la más frecuente, seguida por la MCDNI.¹⁴ A pesar de la alta frecuencia de miocarditis chagásica en Latinoamérica,¹⁵ no hubo ningún caso en esta serie.

¹⁶ Solo en dos casos se realizó estudio electrofisiológico para la inducción de arritmias ventriculares; esta exploración permite elevar el nivel de recomendación a clase I en algunos pacientes seleccionados. La FE promedio del estudio es similar a la publicada en los estudios de prevención secundaria; hubo una menor FE en el grupo de prevención primaria, como era de esperarse, en razón de las diferentes indicaciones para el implante, sin que esta diferencia llegara a ser significativa con respecto al grupo en prevención secundaria.¹⁷ Se ha descrito la utilidad de la amiodarona en los pacientes de prevención secundaria, como medida para evitar y disminuir el número de terapias del dispositivo, o para hacerlas más tolerables al disminuir la frecuencia de la TV y permitir que funcionen los algoritmos antitaquicardia. En esta serie también fue más frecuente su uso en este subgrupo; un paciente de prevención primaria tomaba dicha droga, aún cuando se ha demostrado que no ofrece mayor beneficio en ese grupo, en comparación con el DAI.¹⁸

¹⁹ En esta serie, 2 de los 3 pacientes que recibieron terapias inapropiadas, habían tenido FA.

²⁰ Todas ellas se presentaron en pacientes con dispositivos bicamerales. Solamente un paciente tenía indicación clara de marcapasos antibradicardia por haberse documentado enfermedad del nodo sinusal. Otros 5 pacientes con bloqueo de rama izquierda del haz de His hubieran sido candidatos para el implante de dispositivos tricamerales. La mayor parte de pacientes incluidos en los estudios de eficacia de DAI recibieron un dispositivo unicameral; reportes subsecuentes han mostrado una tendencia actual hacia la implantación de dispositivos bicamerales, pero la ventaja teórica de dichos modelos no ha mostrado clara superioridad con respecto a los unicamerales;²¹ además, la colocación de un número adicional de electrodos incrementa la tasa de complicaciones significativamente.²² Debe tomarse en cuenta que el grupo de pacientes que reciben un DAI bicameral tienen una mayor proporción de morbilidades y puede incluir a algunos a los que se les haya intentado colocar un cable ventricular izquierdo sin éxito. El implante de DAI tricamerales incrementa el riesgo de complicaciones tales como hematomas, desplazamiento de electrodos, disección de seno coronario y muerte cardiovascular,²³ en especial si están tomando anticoagulación o terapia antiplaquetaria en forma concomitante. Desde luego, toda complicación incrementa la estancia y, consecuentemente, los costos de hospitalización.²⁴

^25-27y afectan hasta un 15% de los pacientes a los que se les implanta un DAI,^26,27 cifra que coincide con el número de eventos inapropiados en este estudio. La mayoría habían tenido episodios previos de FA y el desencadenante del choque fue una taquicardia supraventricular mal diagnosticada. El sufrir choques inapropiados condiciona una mayor tasa de recurrencias y mortalidad, por lo que el uso de algoritmos más avanzados y el mejoramiento de la programación, deberían reducirlos;²⁵ se están realizando estudios aleatorizados y multicéntricos con ese objetivo. La incidencia de tormenta eléctrica se reporta entre el 7, 10 y hasta un 25% por año,²⁶ según corresponda a poblaciones con dispositivos tri, uni o bicamerales, respectivamente, pero también se ve influenciada por las distintas poblaciones a las que se les implanta un DAI uni o bicameral. Estas corresponden predominantemente a pacientes con arritmias ventriculares sostenidas o con alto riesgo de MS, en comparación con aquellas en las que se implanta un DAI con resincronización, en quienes predomina la insuficiencia cardiaca. La serie mostró, en concordancia con estudios previos, un mayor riesgo de tormenta eléctrica en pacientes de prevención secundaria; sin embargo, la mayoría de estos pacientes tenía un trasfondo isquémico, lo que contrasta con el hecho que los pacientes con MCDNI son los que, según otros reportes, tienen un mayor riesgo.²⁷ La mayor parte de estos pacientes fueron manejados optimizando la terapia médica y reprogramando las modalidades de terapia; el uso combinado de betabloqueantes y amiodarona ha mostrado reducir el riesgo de choques en forma significativa.²⁸

y reevaluar si está indicado el uso rutinario de DAI bicamerales en pacientes sin una indicación precisa de marcapasos o resincronización.

Conflicto de interés: los autores han recibido apoyo logístico y financiero de los representantes de las marcas Saint Jude Medical y Medtronic, para actividades académicas organizadas por instituciones independientes.

Agradecimiento: Los autores agradecen a la ingeniera Grace Vargas, especialista de producto de SUMEDICAL Costa Rica, por la colaboración prestada en la búsqueda y organización de los expedientes de seguimiento de sus pacientes.

Referencias bibliográficas

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Afiliación de los autores:¹Departamento de Cardiología y Cirugía Cardíaca de la Clínica Universidad de Navarra. ²Servicio de Cardiología del Hospital Calderón Guardia. Universidad de Costa Rica y Universidad de Ciencias Médicas.

Abreviaturas: DAI, desfibrilador automático implantable; FA, fibrilación atrial; FE, fracción de eyección del ventrículo izquierdo; FV, fibrilación ventricular; MS, muerte súbita; MCDNI, miocardiopatía dilatada no isquémica.

^*Correspondencia a: * hugo.arguedas@hotmail.com

Fecha aceptado: 25 de octubre de 2012

Costa Rica: report from the registry of patients with implantable cardioverter-defibrillators, 2007-2011

¹ Oswaldo Gutiérrez-Sotelo²

Cardiology Department, “Dr. Rafael Ángel Calderón Guardia” Hospital, San José, Costa Rica.

Author´s¹Cardiology and Cardiac Surgery Department, Universidad de Navarra (Universtiy of Navarra) Clinic.²Cardiology Department, CalderónGuardiaHospital. Universidad de Costa Rica (University of Costa Rica) and Universidad de Ciencias Médicas (University of Medical Sciences).

Abbreviatons: ICD,Implantable

Cardiac Defibrillator; AF, atrial fibrillation; EF, Left Ventricle Ejection Fraction; VF, ventricular fibrillation; SCD, Sudden Cardiac Death; NIDCM, non ischemic dilated cardiomyopathy. hugo.arguedas@hotmail.com

Background: Several studies have demonstrated the efficacy of implantable cardioverter defibrillators in the prevention of sudden cardiac death. The validation of this evidence has to be assessed through various registries. The objective of this study was to describe the main epidemiological and clinical characteristics of patients who were referred to a tertiary hospital in Costa Rica to be treated with a cardioverter-defibrillators implantable; as well as the associated problems and complications.

Methods: A retrospective observational cohort study, which included all patients who were treated with a cardioverter-defibrillator implantable in the “Dr. Rafael A. Calderón Guardia” hospital between 2007 and 2011.

Results: Twenty three patients were included. The mean age was 55 ± 18 years. Ischemic heart disease was the most frequent etiology (10 patients). Twenty patients had functional class I or II and the mean ejection fraction was 0.38 ± 0.17. In 18 patients, the cardioverter-defibrillator was implanted for secondary prevention. Five patients had an early complication; all of them had dual-chamber devices: 2 minor hematomas, 1 coronary sinus dissection, 1 right atrial lead displacement, and 1 cardio embolic stroke. From a total of 101 therapies (in 8 patients), 94 were appropriate (in 5 patients) and 7 were inappropriate (in 3 patients); 2 of the latter 3 patients had a history of atrial fibrillation episodes.

Conclusion: This registry shows that the majority of implantable cardioverter-defibrillators implantations are performed as a secondary prevention, with a high rate of adequate therapies and a low rate of inadequate ones. The registry allowed an assessment of the indications and complications of this device therapy.

Key words: Implantable defibrillators, sudden death, arrhythmias.

^1-5The risk of death from someone who has had an aborted SCD is nearly 95%; half the survivors will be readmitted within one year and 40% will die within the next 2 years.^2-4SCD risk increases exponentially when the ejection fraction (EF) is less than 0,3.³Functional class also proved to be an independent risk predictor for SCD,^4,5especially in patients with functional class IV, but it only represents one third of such deaths, since the remaining two thirds occur in patients with compensated heart failure symptoms and a functional class II. ^{6, 7}Identification of populations at risk for SCD had little effect in reducing the cumulative incidence, as it mostly occurs in people without identifiable risk factors, namely “healthy” population.

⁸^-10and its superiority against drug treatment. Secondary prevention is defined as those measures applied after an episode of aborted SCD or an episode of sustained ventricular tachycardia (VT), with or without hemodynamic involvement. Primary prevention regards to those measures taken without occurring any such events. International consensus management guidelines have been established ⁹and consequently, there has been an increase in the overall number of implants, therefore the evidence applied to the particular situation in each population center must be evaluated. The only way to achieve this is by conducting surveys and records to compare results with other centers and meet the populations who receive ICD´s. ^10-14The aim of this study was to describe the main epidemiological and clinical characteristics at the time of implantation, as well as knowing the immediate and late complications of the population with an ICD, both for primary and secondary prevention, at a third level hospital in Costa Rica.

San José, Costa Rica. The first ICD implanted at the Cardiology Service was made in 1999, but the implant rate was very low until 2 years ago, when an Electrophysiology program was started. The study was authorized by the Hospital´s Ethics-Scientific Committee, and was not sponsored nor was included in any other study.

Figure 1. Therapy was considered appropriate when the device detected properly an episode of ventricular arrhythmia and administered one programmed therapy, while inappropriate therapy was that which made an inadequate discrimination of an episode of supraventricular arrhythmia, or over-sensing extracardiac signals as myopotentials, or electromagnetic interference. “Electrical storm”, defined as the occurrence of three or more episodes of sustained VT or VF, within a 24 hour period, each separated from the previous one, at least 5 minutes of ventricular arrhythmia-free interval. Early complication was defined as that which occurred in the first 30 days of device implantation, and late complications were those which occurred after that period. A minor complication was that one which did not require a new intervention, hospitalization, or imply a risk to the patient’s life.

Figure 1

Table 1).

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Table 1

Underlying cardiopathy, ejection fraction, functional class and basal rhythms.

Figure 2). Most patients were in functional class I or II at the time of implantation (20 patients). Only 2 patients were in functional class III and one was in class IV. Most of the population had moderate or severe impairment of the FE, with a mean of 0.38 ± 0.17, and in about one third of the population was <0.25. At the time of implantation, 17 patients were in sinus rhythm and five in atrial fibrillation (AF). Nine patients had a previous event of FA. Five patients had left bundle branch block bundle, 3 right bundle branch, 2 had a first-degree atrioventricular block and 1 had Sick Sinus Node Syndrome.

Figure 2

Figure 2).

Table 1). Fifteen secondary prevention patients were medicated with amiodarone, while only one primary prevention patient used it.

Table 2).

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Table 2

Table 3).

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Table 3

Figure 3).

Figure 3

Figure 4). Five patients had an “electrical storm”; they were four secondary prevention patients: 3 with ischemic heart disease and 1 with NIDCM. These 4 patients haven´t recurred, after receiving adjustment of antiarrhythmic medication and reprogramming therapy zones with an antitachycardia pacemaker. The last storm case was a man with NIDCM, functional class IV and FE = 0.15, to whom an ICD with resynchronization therapy was implanted, as a rescue option for his advanced disease. He developed recurrent VT and VF, and received appropriate ICD therapies; however, he died three days later because of terminal heart failure and electromechanical dissociation.

Figure 4

¹¹Although the average age appears to be lower in this study compared to other reports, its variation was in the previously reported ranges.^{12, 13}Underlying heart disease was also distributed similarly, and ischemic heart disease was the most common, followed by NIDCM. ¹⁴Despite the high frequency of chagasic myocarditis in Latin America, ¹⁵there were no cases in this series.

¹⁶Only two patients underwent electrophysiological studies for induction of ventricular arrhythmias; this allows upgrading to class I recommendation in selected patients. The average EF in this study is similar to that published in secondary prevention studies, there was a lower EF in the primary prevention group, as expected, due to the different indications for implantation, although this wasn´t a significant difference compared to the secondary prevention group.¹⁷Usefulness of amiodarone in secondary prevention patients has been described, as a measure to prevent and reduce the number of therapies provided by the device, or to make them more tolerable by decreasing VT frequency and allowing the antitachycardia algorithms to function. In this series, this drug was also more frequently used in this subgroup; a primary prevention patient taking the drug, even when it has been shown that it doesn´t provide greater benefit in this group, compared with the ICD.¹⁸

¹⁹In this series, 2 out of 3 patients who received inappropriate therapies, had FA.

²⁰They all occurred in patients with dual-chamber devices. Only one patient had a clear indication for an anti-bradycardia pacemaker because of Sick Sinus Syndrome. Another 5 patients with left bundle branch block would have been candidates for tricameral device implantation. The majority of patients included in the ICD efficacy studies received an unicameral device, subsequent reports have shown a trend towards the introduction of dual-chamber devices, but the theoretical advantage of such models hasn´t shown a clear superiority over unicameral models; ²¹besides, the placement of an additional number of electrodes significantly increases the complication rate.²²It should be noted that the group of patients receiving a dual chamber ICD had a higher proportion of morbidities and may include some patients that had unsuccessful attempts to put a left ventricular lead. Tricameral ICD implantation increases the risk of complications such as hematomas, electrode displacement, coronary sinus dissection and cardiovascular death, ²³especially if they are taking anticoagulants or antiplatelet therapy concomitantly. Of course, any complication increases stay and hence hospitalization costs.²⁴

^25-27and affect up to 15% of patients who received an ICD, ^26-27which coincides with the number of inapproppriate events in this study. Most had previous episodes of AF and the shock was triggered by a misdiagnosed supra-ventricular tachycardia. Receiving inappropriate shocks lead to higher recurrence and mortality rates, so the use of more advanced algorithms and improved programming should reduce them, ²⁵multicenter randomizedstudiesarebeingmadeforthatpurpose.“Electrical storm” has an incidence between 7, 10 and up to 25% per year, ²⁶as applicable to populations with tri, uni-or bicameral, devices respectively, but also influenced by the different populations that receive uni or bicameral ICD´s. These are mainly in patients with sustained ventricular arrhythmias or high risk of SCD, compared to those in which a cardiac resynchronization capable ICD is implanted, in which heart failure prevails. The series showed, agreeing with previous studies, increased risk of electrical storm in secondary prevention patients; however, most of these patients had an ischemic background, in contrast with the fact that NIDCM patients have a greater risk according to other reports.²⁷Most of these patients were managed optimizing medical treatment and reprogramming therapy modalities; the combined use of beta-blockers and amiodarone has shown to significantly reduce the risk of shocks.²⁸

Costa Rica; this also was a retrospective analysis. Most ICD´s came from a single brand; in the future there will be more information about other brands and their clinical results, as the use of ICDs in primary prevention will become larger.

Costa Rica. Such a record provides valuable information for term standardization prior to ICD implantation, as well as standardizing the indications for which it should be placed in both primary and secondary prevention; besides, it improves the panorama for future decisions about using the most appropriate device, depending on the patient´s characteristics, and allow monitoring the trend of ICD implants, as well as the frequency of complications, and reevaluating if routine use of dual chamber ICDs is indicated in patients without a clear indication for a pacemaker or resynchronization therapy.

Conflict of interest: The authors have received financial and logistical support of the brand representatives Saint Jude Medical and Medtronic, for academic activities organized by independent institutions.

Acknowledgment: The authors thank engineer Grace Vargas, product specialist of SUMEDICAL Costa Rica, for her help in finding and organizing track records of their patients.

en_bart08v55n1 Received Date: March 12^th, 2012 Accepted Date: October 25^th, 2012

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01 Ago 2013
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Mar 2013

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12 Mar 2012
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25 Oct 2012

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<span name="style_bold">Prevención primaria y secundaria de muerte súbita en un hospital de la Seguridad Social de Costa Rica</span>: <span name="style_bold">reporte del registro de pacientes con desfibrilador automático implantable, 2007-2011</span>

<span name="style_bold">Primary and secondary prevention of sudden cardiac death in a hospital of the social security system in Costa Rica</span>: <span name="style_bold">report from the registry of patients with implantable cardioverter-defibrillators, 2007-2011</span>

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