Relation of interatrial block to new-onset atrial fibrillation in patients with Chagas cardiomyopathy and implantable cardioverter-defibrillators.

Chagas cardiomyopathy is an endemic disease in Latin America. A significant proportion of patients develop atrial fibrillation (AF), which may result in stroke and increased morbidity or mortality. Interatrial block (IAB) has been associated with the development of AF in different clinical scenarios. The aim of our study was to determine whether IAB can predict new-onset AF in patients with Chagas cardiomyopathy and implantable cardioverter-defibrillators (ICDs). We conducted a retrospective study of patients with Chagas cardiomyopathy and ICDs from 14 centers in Latin America. Demographics, clinical, and device follow-up were collected. Surface electrocardiograms were scanned at 300 dpi and maximized ×8. Semiautomatic calipers were used to determine P-wave onset and offset. Partial IAB was defined as a P wave of >120 ms and advanced IAB as a P wave of >120 ms with biphasic morphology (±) in inferior leads. AF events and ICD therapies were reviewed during follow-up by 2 independent investigators. A total of 80 patients were analyzed. Mean age was 54.6 ± 10.4 years, and 52 (65%) were male. Mean left ventricular ejection fraction was 40 ± 12%. IAB was detected in 15 patients (18.8%), with 8 (10.0%) partial and 7 (8.8%) advanced. During a follow-up of 33 ± 20 months, 11 patients (13.8%) presented with new AF. IAB (partial + advanced) was strongly associated with new AF (p <0.0001) and inappropriate therapy by the ICD (p = 0.014). In conclusion, IAB (partial + advanced) predicted new-onset AF in patients with Chagas cardiomyopathy and ICDs.

Fragmented surface ECG was a poor predictor of appropriate therapies in patients with Chagas' cardiomyopathy and ICD implantation (Fragmented ECG in CHAgas' Cardiomyopathy Study).

BACKGROUND: Main causes of death in chronic Chagas' cardiomyopathy (CChC) are progressive congestive heart failure and sudden cardiac death. Implantable cardioverter defibrillators (ICD) have been proved an effective therapy to prevent sudden death in patients with CChC. Identification of predictors of sudden death remains a challenge. OBJECTIVE: To determine whether surface fragmented ECG (fQRS) helps identifying patients with CChC and ICDs at higher risk of presenting appropriate ICD therapies. METHODS: Multicenter retrospective study. All patients with CChC and ICDs were analyzed. Clinical demographics, surface ECG, and ICD therapies were collected. RESULTS: A total of 98 patients were analyzed. Another four cases were excluded due to pacing dependency. Mean age was 55.5 ± 10.4 years, male gender 65%, heart failure New York Heart Association class I 47% and II 38%. Mean left ventricular ejection fraction (LVEF) 39.6 ± 11.8%. The indication for ICD was secondary prevention in 70% of patients. fQRS was found in 56 patients (59.6%). Location of fragmentation was inferior (57.1%), lateral (35.7%), and anterior (44.6%). Rsr pattern was the more prevalent (57.1%). Predictors of appropriate therapy in the multivariate model were: increased age (P = 0.01), secondary prevention indication (P = 0.01), ventricular pacing >50% of the time (P = 0.004), and LVEF <30% (P = 0.01). The presence of fQRS did not identify patients at higher risk of presenting appropriate therapies delivered by the ICD (P = 0.87); regardless of QRS interval duration. CONCLUSIONS: fQRS is highly prevalent among patients with CChC. It has been found a poor predictor of appropriate therapies delivered by the ICD in this population.

Usefulness of vernakalant hydrochloride injection for rapid conversion of atrial fibrillation.

The objective of the present study was to assess the safety and effectiveness of vernakalant hydrochloride injection (RSD1235), a novel antiarrhythmic drug, for the conversion of atrial fibrillation (AF) or atrial flutter to sinus rhythm (SR). Patients with either AF or atrial flutter were randomized in a 1:1 ratio to receive vernakalant (n = 138) or placebo (n = 138) and were stratified by an arrhythmia duration of >3 hours to ≤7 days (short duration) and 8 to ≤45 days (long duration). The first infusion of placebo or vernakalant (3 mg/kg) was given for 10 minutes followed by a second infusion of placebo or vernakalant (2 mg/kg) 15 minutes later if the arrhythmia had not terminated. A total of 265 patients were randomized and received treatment. The primary end point was conversion of AF to SR for ≥1 minute within 90 minutes of the start of the drug infusion in the short-duration AF group. Of the 86 patients receiving vernakalant in the short-duration AF group, 44 (51.2%) demonstrated conversion to SR compared to 3 (3.6%) of the 84 in the placebo group (p <0.0001). The median interval to conversion of short-duration AF to SR in the responders given vernakalant was 8 minutes. Of the entire AF population (short- and long-duration AF), 47 (39.8%) of the 118 vernakalant patients experienced conversion of AF to SR compared to 4 (3.3%) of the 121 placebo patients (p <0.0001). Transient dysgeusia and sneezing were the most common adverse events in the vernakalant patients. One vernakalant patient who had severe aortic stenosis experienced hypotension and ventricular fibrillation and died. In conclusion, vernakalant demonstrated a rapid and high rate of conversion for short-duration AF and was well tolerated.

Subanalyses of secondary prevention implantable cardioverter-defibrillator trials: antiarrhythmics versus implantable defibrillators (AVID), Canadian Implantable Defibrillator Study (CIDS), and Cardiac Arrest Study Hamburg (CASH).

PURPOSE OF REVIEW: Controlled trials for secondary prevention of sudden death--Antiarrhythmics Versus Implantable Defibrillators (AVID), Canadian Implantable Defibrillator Study (CIDS), and Cardiac Arrest Study Hamburg (CASH)--have been published and subanalyses of them provide useful clinical information on the outcome during the follow-up of this population. RECENT FINDINGS: Results from a meta-analysis showed a significant risk reduction (RR) of 25 to 27% of total mortality (P < 0.001) and 50 to 52% of arrhythmic death (P < 0.001). Compared with amiodarone, patients treated with an implantable cardioverter-defibrillator (ICD) in AVID had a maximal benefit in survival when the ejection fraction (EF) was between 20 and 34%. In CIDS, the group of higher risk (older than 70 years, EF less than 3.5%, and New York Heart Association class III-IV) presented a 50% RR of mortality. It has been demonstrated that the imbalance in beta-blocker use cannot explain the better survival in the ICD patients. After 3 years the recurrence of arrhythmia was 64% in the ICD group of the AVID trial. Patients enrolled after an episode of ventricular tachycardia were more likely to have appropriate therapy during follow-up. Older age, lower blood pressure, history of atrial fibrillation, diabetes, congestive heart failure, and prior pacemaker were parameters used for high-risk stratification. Conversely, inducibility of ventricular tachyarrhythmias on electrophysiology did not predict death. SUMMARY: Patients with ICD after ventricular tachyarrhythmias have a 28% RR in total mortality. Individuals with EF between 20 to 34% received the highest benefit with ICD therapy.

Ablación por radiofrecuencia en niños y adolescentes con taquicardia paroxística supraventricular, sin cardiopatía estructural / Radioablation for paroxysmal SVT without cardiopathy in children and adolescents

Introducción: la ablación transcatéter por radiofrecuencia constituye una alternativa terapéutica curativa para diferentes taquiarritmias cardíacas, evitando crisis reiteradas, así como el uso de fármacos antiarrítmicos en forma crónica, con un procedimiento menos agresivo y costoso que la cirugía. Este trabajo evalúa retrospectivamente nuestra experiencia con este método terapéutico en niños y adolescentes fuertemente sintomáticos, con taquicardia paroxística supraventricular y un corazón estructuralmente sano. Poblacion: costó de 56 pacientes consecutivos, con edades de 6 a 18 años (x: 13 ñ 3, X: 13) y taquicardias reiteradas a pesar del tratamiento antiarrítmico, 3 de los cuales presentaban, además, antecedentes de síncope y muerte súbita. Material y métodos: el diagnóstico electrofisiológico incluyó: taquicardia por reentrada AV, utilizando una vía accesoria, en 48 pacientes, de los cuales 34 tenían síndrome de Wolff-Parkinson-White y taquicardia reentrante nodal en 8. A continuación se procedió a realizar la ablación por radiofrecuencia. Resultados: la ablación fue primariamente exitosa en 52 pacientes (93 porciento). La duración total del procedimiento fue de 226 ñ 143 min, x: 210 minutos, el tiempo de radioscopia, 42 ñ 33 min, x: 40 min y el número de aplicaciones de radiofrecuencia, 4 ñ 3, x: 2 pulsos. Se presentaron complicaciones en sólo 3 casos (5,4 porciento). Durante un seguimiento de 0,5 a 7,5 años (3,3 ñ 1,7, X: 2,5), 10 pacientes sufrieron recidivas, repitiéndose exitosamente la ablación en 6 de ellos. El procedimiento fue considerado curativo en 48 de 56 pacientes (86 porciento). Conclusiones: nuestra experiencia con ablación por radiofrecuencia en esta población fue ampliamente satisfactoria, con alto índice de efectividad, escasa morbilidad y mortalidad nula

Ablación por radiofrecuencia en niños y adolescentes con taquicardia paroxística supraventricular, sin cardiopatía estructural

Introducción: la ablación transcatéter por radiofrecuencia constituye una alternativa terapéutica curativa para diferentes taquiarritmias cardíacas, evitando crisis reiteradas, así como el uso de fármacos antiarrítmicos en forma crónica, con un procedimiento menos agresivo y costoso que la cirugía. Este trabajo evalúa retrospectivamente nuestra experiencia con este método terapéutico en niños y adolescentes fuertemente sintomáticos, con taquicardia paroxística supraventricular y un corazón estructuralmente sano. Población: constó de 56 pacientes consecutivos, con edades de 6 a 18 años (x: 13±3, X: 13) y taquicardias reiteradas a pesar del tratamiento antiarrítmico, tres de los cuales presentaban, además, antecedentes de síncope y muerte súbita. Material y métodos: el diagnóstico electrofisiológico incluyó: taquicardia por reentrada AV, utilizando una vía accesoria, en 48 pacientes, de los cuales 34 tenían síndrome de Wolff-Parkinson-White y taquicardia reentrante nodal en 8. A continuación se procedió a realizar la ablación por radiofrecuencia. Resultados: la ablación fue primariamente exitosa en 52 pacientes (93%). La duración total del procedimiento fue de 226±143, X: 210 minutos, el tiempo de radioscopia, 42±33, X: 40 minutos y el número de aplicaciones de radiofrecuencia, 4±3, X: 2 pulsos. Se presentaron complicaciones en sólo tres casos (5,4%). Durante un seguimiento de 0,5 a 7,5 años (3,3±1,7, X: 2,5), 10 pacientes sufrieron recidivas, repitiéndose exitosamente la ablación en seis de ellos. El procedimiento fue considerado curativo en 48 de 56 pacientes (86%). Conclusiones: nuestra experiencia con ablación por radiofrecuencia en esta población fue ampliamente satisfactoria, con alto índice de efectividad, escasa morbilidad y mortalidad nula.

Introducção: A ablação transcatéter por radiofrequência constitui uma altenativa terapéutica curativa para diferentes taquiarritmias cardíacas, evitando crises frequentes, assim como o uso de fármacos antiarrítmicos em forma crônica, com um procedimento menos agressivo e custoso que a cirurgia. Este trabalho avalia restrospectivamente nossa experiência com este método terapéutico em crianças e adolescentes fortemente sintomáticos, com taquicardia paroxística supraventricular e um coração estruturalmente sem problemas. População: Contou com 52 pacientes consecutivos, com idades de 6 a 18 anos (x: 13 ± 3, X: 13) e taquicardias reiteradas a pesar do tratamento antiarrítmico, 3 dos quais apresentavam, também antecedentes de síncope e morte súbita. Material é método: O diagnóstico electro fisiológico incluíu: taquicardia por reentrada AV, utilizando uma vía acessória em 48 pacientes, dos quais 34 tinham síndrome de Wolf-Parkinson-White e taquicardia reentrante nodal em 8. A continuação procedeu-se a realizar a ablação por radiofrequência. Resultados: a ablação foi primariamente exitosa em 52 pacientes (93%). A duração total do procedimento foi de 226 ± 143, X: 210 minutos, o tempo de radioscopia, 42 ± 33, X: 40 minutos e o número de aplicações de radiofrequência, 4 ± 3, X: 2 pulsos. Apresentaram-se complicações em só 3 casos (5,4%). Durante o seguimento de 0,5 a 7,5 anos (3,3 ± 1,7, X:2,5), 10 pacientes sofreram recidivas, repetindo-se exitosamente a ablação em 6 deles. O procedimento foi considerado curativo em 48 dos 56 pacientes (86%). Conclusões: Nossa experiência com ablação por radiofrequência foi ampliamente satifatoria, com alto índice de efetividade, escassa morbilidade e mortalidade nula.

Introduction: radiofrequency catheter ablation provides curative therapy for several tachyarrhythmias, avoiding repeated crisis, as well as the chronic use of antiarrythmic drugs, with a less aggressive and costly procedure than surgery. This article retrospectively evaluates our experience with such method in children and adolescents highly symptomatic, with paroxysmal supraventricular tachycardia and structurally normal hearts. Population: the study consisted in 56 consecutive patients aged 6 to 18 years (13±3, X: 13 years) with recurrent tachycardia in spite of pharmacological treatment, 3 of them with syncope and suden death. Material and methods: electrophysiology diagnosis included: Reentrant tachycardia using an accessory pathway in 48 patients, 34 associated with Wolff- Parkinson-White syndrome, and reciprocant nodal tachycardia in eight patients. Results: ablation was primaryly successful in 52 patients (93%). Total procedural time was x: 226±43, X: 210 minutes; fluoroscopylasted x: 42±33, X: 40 minutes and radiofrequency pulses averaged 4±3, X: 2. Complications presented in only 3 patients (5,4%). During a follow-up of 0,5 to 7,5 years (x: 3,3±1,7, X: 2,5), 10 patients suffered recurrences, being successfully re-ablationed 6/6 of them. The procedure was considered curative in 48/56 patients (86%). Conclusions: our prelimiriary experience with radiofrequency ablation in this group was largely satisfactory, with high effectivity, few morbidity and no mortality.

Ritmo idioventricular acelerado: ¿marcador de reperfusión coronaria? / Accelerated idioventricular rhythm: coronary reperfusion marker?

Se presentan los resultados retrospectivos de 41 pacientes de ambos sexos que ingresaron en el lapso de 12 meses a la Unidad Coronaria del Hospital Eva Perón de San Martín. El objetivo fue conocer con qué frecuencia el ritmo idioventricular acelerado se asociaba en esta serie de pacientes con la reperfusión coronaria. Todos fueron admitidos con diagnóstico de infarto agudo de miocardio y presentaron ritmo idioventricular acelerado; 38 recibieron tratamiento fibrinolítico y 3 se consideraron reperfundidos espontáneamente. El ritmo idioventricular acelerado se presentó en 90 por ciento de los pacientes reperfundidos (37/41). En 75 por ciento de los casos el ritmo idioventricular acelerado fue precoz, sucediendo dentro de los primeros 120 minutos en promedio. En un grupo de estos pacientes el ritmo idioventricular acelerado ocurrió antes que el segmento ST alcanzara su nivel normal. Ninguno de ellos falleció durante la hospitalización. Para concluir podríamos decir que un ritmo idioventricular acelerado regular, que se presenta dentro de las primeras 4 horas de evolución de un infarto agudo de miocardio y cuyo intervalo de acoplamiento es prolongado, es indicador de que se logró la reperfusión

Ritmo idioventricular acelerado: ¿marcador de reperfusión coronaria? / Accelerated idioventricular rhythm: coronary reperfusion marker?

Se presentan los resultados retrospectivos de 41 pacientes de ambos sexos que ingresaron en el lapso de 12 meses a la Unidad Coronaria del Hospital Eva Perón de San Martín. El objetivo fue conocer con qué frecuencia el ritmo idioventricular acelerado se asociaba en esta serie de pacientes con la reperfusión coronaria. Todos fueron admitidos con diagnóstico de infarto agudo de miocardio y presentaron ritmo idioventricular acelerado; 38 recibieron tratamiento fibrinolítico y 3 se consideraron reperfundidos espontáneamente. El ritmo idioventricular acelerado se presentó en 90 por ciento de los pacientes reperfundidos (37/41). En 75 por ciento de los casos el ritmo idioventricular acelerado fue precoz, sucediendo dentro de los primeros 120 minutos en promedio. En un grupo de estos pacientes el ritmo idioventricular acelerado ocurrió antes que el segmento ST alcanzara su nivel normal. Ninguno de ellos falleció durante la hospitalización. Para concluir podríamos decir que un ritmo idioventricular acelerado regular, que se presenta dentro de las primeras 4 horas de evolución de un infarto agudo de miocardio y cuyo intervalo de acoplamiento es prolongado, es indicador de que se logró la reperfusión (AU)