Comportamiento del tiempo de conducción retrógrada al momento de la inducción de las taquicardias supraventriculares y su rol en el diagnóstico diferencial / Behavior of Retrograde Conduction Time at Supraventricular Tachycardia Induction and its Role in Differential Diagnosis

RESUMEN Antecedentes : El diagnóstico diferencial entre la taquicardia reentrante ortodrómica (TRO) y la taquicardia por reentrada nodal atípica (TRNa) puede ser dificultoso. Nuestra hipótesis es que las TRNa tienen más variabilidad en el tiempo de con ducción retrógrada al comienzo de la taquicardia que las TRO. Nuestros objetivos fueron evaluar la variabilidad en el tiempo de conducción retrógrada al inicio de la taquicardia en TRNa y TRO, y proponer una nueva herramienta diagnóstica para diferenciar estas dos arritmias. Métodos : Se midió el intervalo ventrículo-auricular (VA) de los primeros latidos tras la inducción de la taquicardia, hasta su estabilización. La diferencia entre el intervalo VA máximo y el mínimo se definió como delta VA (ΔVA). También contamos el número de latidos necesarios para que se estabilice el intervalo VA. Se excluyeron las taquicardias auriculares. Resultados : Se incluyeron 101 pacientes. Se diagnosticó TRO en 64 pacientes y TRNa en 37. El ΔVA fue 0 (rango intercuartílico, RIC, 0-5) milisegundos (ms) en la TRO frente a 40 (21-55) ms en la TRNa (p < 0,001). El intervalo VA se estabilizó significativamente antes en la TRO (1,5 [1-3] latidos) que en la TRNa (5 [4-7] latidos; p < 0,001). Un ΔVA < 10 ms diagnosticó TRO con 100% de sensibilidad, especificidad y valores predictivos positivo y negativo. La estabilización del intervalo VA en menos de 3 latidos predijo TRO con buena precisión diagnóstica. Los resultados fueron similares considerando sólo vías accesorias septales. Las TRN típicas tuvieron una variación intermedia. Conclusión : Un ΔVA < 10 ms es un criterio simple, que distingue con precisión la TRO de la TRNa, independientemente de la localización de la vía accesoria.

ABSTRACT Background : Differential diagnosis between orthodromic reentrant tachycardia (ORT) and atypical nodal reentrant tachy cardia (ANRT) can be challenging. Our hypothesis was that ANRT presents more variability in retrograde conduction time at tachycardia onset than ORT. Objectives : The objectives of this study were to assess retrograde conduction time variability at the start of tachycardia in ANRT and ORT, and postulate a new diagnostic tool to differentiate these two types of arrhythmias. Methods : The ventriculoatrial (VA) interval of the first beats after tachycardia induction was measured until stabilization. The difference between the maximum and minimum VA interval was defined as delta VA (ΔVA), and the number of beats needed for VA interval stabilization was also assessed. Atrial tachycardias were excluded. Results : In a total of 101 patients included in the study, ORT was diagnosed in 64 patients and ANRT in 37. ΔVA interval was 0 (interquartile range [IQR] 0-5) milliseconds (ms) in ORT vs. 40 (21-55) ms in ANRT (p <0.001). The VA interval significantly stabilized earlier in ORT (1.5 [1-3] beats) than in ANRT (5 [4-7] beats) (p<0.001). A ΔVA <10 ms diagnosed ORT with 100% sensitivity, specificity, and positive and negative predictive values. Ventriculoatrial interval stabilization in less than 3 beats predicted ORT with good diagnostic accuracy. The results were similar considering only accessory septal pathways. Typical NRTs presented an intermediate variation. Conclusion : Presence of DVA <10 ms is a simple criterion that accurately differentiates ORT from ANRT, independently of the accessory pathway localization.

Variability of the VA interval at tachycardia induction: a simple method to differentiate orthodromic reciprocating tachycardia from atypical atrioventricular nodal reentrant tachycardia.

BACKGROUND: The differential diagnosis between orthodromic atrioventricular reentry tachycardia (AVRT) and atypical AV nodal reentrant tachycardia (aAVNRT) is sometimes challenging. We hypothesize that aAVNRTs have more variability in the retrograde conduction time at tachycardia onset than AVRTs. METHODS: We aimed to assess the variability in retrograde conduction time at tachycardia onset in AVRT and aAVNRT and to propose a new diagnostic tool to differentiate these two arrhythmia mechanisms. We measured the VA interval of the first beats after tachycardia induction until it stabilized. The difference between the maximum and minimum VA intervals (∆VA) and the number of beats needed for the VA interval to stabilize was analyzed. Atrial tachycardias were excluded. RESULTS: A total of 107 patients with aAVNRT (n = 37) or AVRT (n = 64) were included. Six additional patients with decremental accessory pathway-mediated tachycardia (DAPT) were analyzed separately. All aAVNRTs had VA interval variability. The median ∆VA was 0 (0 - 5) ms in AVRTs vs 40 (21 - 55) ms in aAVNRTs (p < 0.001). The VA interval stabilized significantly earlier in AVRTs (median 1.5 [1 - 3] beats) than in aAVNRTs (5 [4 - 7] beats; p < 0.001). A ∆VA < 10 ms accurately differentiated AVRT from aAVNRT with 100% of sensitivity, specificity, and positive and negative predictive values. The stabilization of the VA interval at < 3 beats of the tachycardia onset identified AVRT with sensitivity, specificity, and positive and negative predictive values of 64.1%, 94.6%, 95.3%, and 60.3%, respectively. A ∆VA < 20 ms yielded good diagnostic accuracy for DAPT. CONCLUSIONS: A ∆VA < 10 ms is a simple and useful criterion that accurately distinguished AVRT from atypical AVNRT. Central panel: Scatter plot showing individual values of ∆VA in atypical AVNRT and AVRT. Left panel: induction of atypical AVNRT. The VA interval stabilizes at the 5th beat and the ∆VA is 62 ms (maximum VA interval: 172 ms - minimum VA interval: 110 ms). Right panel: induction of AVRT. The tachycardia has a fixed VA interval from the first beat. ∆VA is 0 ms.

Catheter ablation of ventricular tachycardia in patients with electrical storm, with a special focus on patients with Chagas disease.

BACKGROUND: There are few reports on the benefits of catheter ablation (CA) in patients with electrical storm (ES). None of these publications included patients with Chagas disease (ChD). Our aims are to analyze (1) all the cases of ES treated with CA and (2) the subgroup of patients with ChD. METHODS: Prospective analysis of consecutive patients with ES due to monomorphic ventricular tachycardia (VT) treated with CA. RESULTS: We included 38 patients: 28 males; median age of 63.5 (IQR 55-71) years old; ejection fraction (LVEF) 0.30 (0.25-0.40). Sixteen patients (42.1%) had ChD. The patients experienced 21 (15-37) VT episodes and received 7 (3-13) ICD shocks before CA. Forty-six procedures were performed (7 required epicardial access). All patients experienced ES suppression after CA. After 35 (10-64) months of follow-up (1.21 procedures per patient), 23 patients (60.5%) remain free from any VT; 35 patients (92.1%) were free from ES, and 11 patients (28.9%) died from non-arrhythmic causes. One patient underwent heart transplantation. Patients with ChD were younger (60 vs. 67 years old; p = 0.033), significantly more women (50% vs. 9.1%; p = 0.005), and had higher LVEF (0.40 vs. 0.28; p < 0.001) than the other patients. Long-term outcome of ChD patients was similar to that of the overall population. Only age and LVEF independently predicted mortality. CONCLUSION: CA was associated with acute ventricular arrhythmia suppression in all patients with ES. Freedom rates from ES and VT were 92.1% and 60.5% respectively. Despite having a lower-risk clinical profile, patients with ChD had a comparable outcome to that of the other patients.

Catheter ablation in Patients with Electrical storm: The Calm after the Tempest / Ablación por catéter en pacientes con tormenta eléctrica: La calma tras la tempestad

Background: Catheter ablation (CA) has been shown to be effective in patients with recurrent ventricular tachycardia (VT); how-ever, its role in patients with electrical storm (ES) has not been studied in randomized trials. Objective: The aim of this study was to analyze ES cases treated with CA. Methods: This was a retrospective analysis of patients treated with CA for ES due to sustained monomorphic VT (SMVT). Procedure success was defined as lack of inducible VT at the end of ablation, partial success as the induction of non-clinical VT and failure as inducible clinical V T. Results:Sixteen procedures were performed in 14 patients: 10 successful, 3 partially successful and 3 failures. All patients were free from ventricular arrhythmia immediately after ablation. Ten patients (71.4%) were free from VT and 86.7% free from ES [8 (3-30)-month follow-up]. Five patients (35.7%) died from causes unrelated to arrhythmia. Conclusions: Catheter ablation is associated with acute suppression of VT in all patients with ES due to SMVT and with a recurrence-free outcome in most of them.

Introducción: La ablación por catéter (AC) ha demostrado que es beneficiosa en pacientes con taquicardia ventricular (TV) recur­rente, pero su rol en pacientes con tormenta eléctrica (TE) no se ha estudiado en ensayos aleatorizados. Objetivo: Analizar los casos de TE tratados con AC. Material y métodos: Análisis retrospectivo de pacientes con TE debida a TV monomorfa sostenida (TVMS) tratados mediante AC. Se definió éxito del procedimiento a la ausencia de TV inducible al final de la ablación, éxito parcial a la inducción de TV no clínica y no éxito a la inducibilidad de la TV clínica. Resultados:Se realizaron 16 procedimientos en 14 pacientes: 10 exitosos, 3 éxito parcial y 3 no exitosos. Todos los pacientes evolucionaron sin arritmia ventricular inmediatamente posablación. Diez pacientes (71,4%) evolucionaron sin TV y el 86,7% sin TE [seguimiento 8 (3-30) meses]. Cinco pacientes (35,7%) murieron de causa no arrítmica. Conclusiones: La AC se asocia con una supresión aguda de la TV en todos los pacientes con TE debida a TVMS y con una evolución sin recurrencia en la mayoría de ellos.

Aplicación y comparación de los puntajes de riesgo CHADS2 y CHA2DS2-VASc en una población con fibrilación auricular / Application and Comparison of the CHADS2 and CHA2DS2-VASc Risk Scores in a Population with Atrial Fibrillation

Introducción El puntaje CHADS2 y el recientemente adoptado por la comunidad médica CHA2DS2-VASc se han elaborado con datos de registros internacionales y son ampliamente usados en la práctica clínica. Sin embargo, no se han evaluado en registros nacionales. Objetivos Evaluar el poder de predicción de los puntajes de riesgo de accidente cerebrovascular CHADS2 y CHA2DS2-VASc en el Registro de Fibrilación Auricular realizado por el Área de Investigación de la Sociedad Argentina de Cardiología y secundariamente comparar ambos sistemas de puntaje. Material y métodos El Registro de Fibrilación Auricular realizado en 2001 fue un estudio multicéntrico y prospectivo de todos los pacientes consecutivos asistidos por fibrilación auricular crónica (permanente y persistente) en 70 centros médicos de la Argentina. Se obtuvieron los datos demográficos, las características socioeconómicas, los antecedentes y las características clínicas. Se realizó un seguimiento a 2 años en el que se evaluó la tasa de accidente cerebrovascular. Para el presente análisis se seleccionaron los pacientes sin tratamiento anticoagulante. En esta población se evaluaron los dos sistemas de puntaje de riesgo, se confeccionó una curva de ROC para cada puntaje (que se informa como estadístico C) y se realizó una comparación entre ambos sistemas de puntaje. Resultados El 49,3% (303 pacientes) de los pacientes seguidos no recibían tratamiento anticoagulante y constituyeron nuestra población en estudio. La tasa de accidente cerebrovascular en la población seleccionada fue del 9,5%. Los dos sistemas de puntaje de riesgo predijeron el accidente cerebrovascular significativamente. La tasa de accidente cerebrovascular fue aumentando a medida que aumentaba el puntaje del CHADS2 y el del CHA2DS2-VASc; este aumento fue similar en ambas escalas de riesgo. El estadístico C para accidente cerebrovascular del CHADS2 fue de 0,67 (0,55-0,78) y el del CHA2DS2-VASc fue de 0,69 (0,59-0,78), sin diferencias significativas entre ambos. Con el análisis de los puntajes divididos en tres perfiles de riesgo -bajo, moderado y alto- se observó que el poder de predicción disminuyó notablemente; el valor del estadístico C del CHADS2 fue de 0,63 (IC 95% 0,57-0,68) y el del CHA2DS2-VASc fue de 0,57 (IC 95% 0,51- 22 0,62),una ligera tendencia a predecir mejor el CHADS2 pero sin significación estadística. Conclusiones En una población con fibrilación auricular de la República Argentina se observó que los dos sistemas de puntaje de predicción de accidente cerebrovascular en pacientes con fibrilación auricular permanente y persistente tienen un poder de predicción similar entre ellos y similar al referido en la bibliografía.

Introduction The CHADS2 score and the CHA2DS2-VASc score recently ad-opted by the medical community have been developed with international registry data and are widely used in clinical practice. However, they have not been evaluated in national registries. Objectives The aims of this study were first to evaluate the predictive power of the CHADS2 and CHA2DS2-VASc stroke risk scores in the Atrial Fibrillation Registry conducted by the Argentine Society of Cardiology Research Area and second to compare both scoring systems. Methods The Atrial Fibrillation Registry of 2001 was a multicenter, prospective study of all consecutive patients with chronic atrial fibrillation (permanent, persistent) treated in 70 medical centers in Argentina. Demographic data, socioeco-nomic characteristics, background and clinical features were obtained. A 2-year follow-up was performed to assess stroke rate. For the present analysis patients without anticoagulant treatment were selected. In this population, the two risk score systems were assessed; a ROC curve was built for each score (reported as c-statistic) and a comparison between both scoring systems was performed. Results The study population consisted of 303 patients (49.3%) not receiving anticoagulant therapy. The stroke rate in the se-lected population was 9.5%. Both scoring systems predicted significant stroke risk. The stroke rate increased as the CHADS2 and the CHA2DS2-VASc scores were higher, and were similar in both risk scales. The CHADS2 and CHA2DS2-VASc scores had c-statistic values of 0.67 (0.55-0.78) and 0.69 (0.59-0.78), respectively, without significant differences between them. The score analyses divided into three risk profiles -low, mod-erate and high- revealed that the predictive power decreased markedly. The c-statistic value of the CHADS2 was 0.63 (95% CI 0.57-0.68) and that of the CHA2DS2-VASc score was 0.57 (95% CI 0.51-0.62), with a slightly better predictive trend for the CHADS2 score but without statistical significance. Conclusions The two scoring systems used to predict stroke in an Argen-tine population of patients with persistent and permanent atrial fibrillation have a similar predictive power in accor-dance with results reported in the literature.

Aplicación y comparación de los puntajes de riesgo CHADS2 y CHA2DS2-VASc en una población con fibrilación auricular / Application and Comparison of the CHADS2 and CHA2DS2-VASc Risk Scores in a Population with Atrial Fibrillation

Introducción El puntaje CHADS2 y el recientemente adoptado por la comunidad médica CHA2DS2-VASc se han elaborado con datos de registros internacionales y son ampliamente usados en la práctica clínica. Sin embargo, no se han evaluado en registros nacionales. Objetivos Evaluar el poder de predicción de los puntajes de riesgo de accidente cerebrovascular CHADS2 y CHA2DS2-VASc en el Registro de Fibrilación Auricular realizado por el Area de Investigación de la Sociedad Argentina de Cardiología y secundariamente comparar ambos sistemas de puntaje. Material y métodos El Registro de Fibrilación Auricular realizado en 2001 fue un estudio multicéntrico y prospectivo de todos los pacientes consecutivos asistidos por fibrilación auricular crónica (permanente y persistente) en 70 centros médicos de la Argentina. Se obtuvieron los datos demográficos, las características socioeconómicas, los antecedentes y las características clínicas. Se realizó un seguimiento a 2 años en el que se evaluó la tasa de accidente cerebrovascular. Para el presente análisis se seleccionaron los pacientes sin tratamiento anticoagulante. En esta población se evaluaron los dos sistemas de puntaje de riesgo, se confeccionó una curva de ROC para cada puntaje (que se informa como estadístico C) y se realizó una comparación entre ambos sistemas de puntaje. Resultados El 49,3% (303 pacientes) de los pacientes seguidos no recibían tratamiento anticoagulante y constituyeron nuestra población en estudio. La tasa de accidente cerebrovascular en la población seleccionada fue del 9,5%. Los dos sistemas de puntaje de riesgo predijeron el accidente cerebrovascular significativamente. La tasa de accidente cerebrovascular fue aumentando a medida que aumentaba el puntaje del CHADS2 y el del CHA2DS2-VASc; este aumento fue similar en ambas escalas de riesgo. El estadístico C para accidente cerebrovascular del CHADS2 fue de 0,67 (0,55-0,78) y el del CHA2DS2-VASc fue de 0,69 (0,59-0,78), sin diferencias significativas entre ambos. Con el análisis de los puntajes divididos en tres perfiles de riesgo -bajo, moderado y alto- se observó que el poder de predicción disminuyó notablemente; el valor del estadístico C del CHADS2 fue de 0,63 (IC 95% 0,57-0,68) y el del CHA2DS2-VASc fue de 0,57 (IC 95% 0,51- 22 0,62),una ligera tendencia a predecir mejor el CHADS2 pero sin significación estadística. Conclusiones En una población con fibrilación auricular de la República Argentina se observó que los dos sistemas de puntaje de predicción de accidente cerebrovascular en pacientes con fibrilación auricular permanente y persistente tienen un poder de predicción similar entre ellos y similar al referido en la bibliografía.(AU)

Introduction The CHADS2 score and the CHA2DS2-VASc score recently ad-opted by the medical community have been developed with international registry data and are widely used in clinical practice. However, they have not been evaluated in national registries. Objectives The aims of this study were first to evaluate the predictive power of the CHADS2 and CHA2DS2-VASc stroke risk scores in the Atrial Fibrillation Registry conducted by the Argentine Society of Cardiology Research Area and second to compare both scoring systems. Methods The Atrial Fibrillation Registry of 2001 was a multicenter, prospective study of all consecutive patients with chronic atrial fibrillation (permanent, persistent) treated in 70 medical centers in Argentina. Demographic data, socioeco-nomic characteristics, background and clinical features were obtained. A 2-year follow-up was performed to assess stroke rate. For the present analysis patients without anticoagulant treatment were selected. In this population, the two risk score systems were assessed; a ROC curve was built for each score (reported as c-statistic) and a comparison between both scoring systems was performed. Results The study population consisted of 303 patients (49.3%) not receiving anticoagulant therapy. The stroke rate in the se-lected population was 9.5%. Both scoring systems predicted significant stroke risk. The stroke rate increased as the CHADS2 and the CHA2DS2-VASc scores were higher, and were similar in both risk scales. The CHADS2 and CHA2DS2-VASc scores had c-statistic values of 0.67 (0.55-0.78) and 0.69 (0.59-0.78), respectively, without significant differences between them. The score analyses divided into three risk profiles -low, mod-erate and high- revealed that the predictive power decreased markedly. The c-statistic value of the CHADS2 was 0.63 (95% CI 0.57-0.68) and that of the CHA2DS2-VASc score was 0.57 (95% CI 0.51-0.62), with a slightly better predictive trend for the CHADS2 score but without statistical significance. Conclusions The two scoring systems used to predict stroke in an Argen-tine population of patients with persistent and permanent atrial fibrillation have a similar predictive power in accor-dance with results reported in the literature.(AU)

Diagnóstico diferencial entre doble respuesta ventricular y extrasistolia hisiana bigeminada / Differential diagnosis between dual ventricular response and bigeminy arising from the bundle of his

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Single oral flecainide dose to unmask type 1 Brugada syndrome electrocardiographic pattern.

BACKGROUND: Brugada syndrome (BrS) includes a group of patients with a typical pattern of ST segment elevation in right precordial leads who are at risk for sudden cardiac death. The electrocardiogram pattern may be intermittent and unmasked by sodium channel blockers. The main objective of this study is to describe a serie of consecutive patients in whom oral administration of flecainide was used to unmask BrS type I electrocardiographic pattern. METHODS: We prospectively studied 14 symptomatic (palpitations/syncope) patients referred to our laboratory presenting a suggestive but not diagnostic Brugada ECG or family history of sudden death. Single oral dose of flecainide 400 mg was administered. Resting 12-lead ECG with upper and standard right precordial leads were performed after flecainide administration at 15, 30, 60 and 90 min and hourly until ECG became normal. RESULTS: Median age was 37.5 years (range = 22-50). None of them had structural heart disease. In 7 patients (50%) the typical coved-type ECG pattern of BrS was unmasked. PR interval, QRS duration and QTc median difference after-before test was 20 msec (min-max = -17-+57), 21 ms (min-max = 0 to +59) and 20 ms (min-max = -11-+77), respectively. There were no episodes of AV block, atrial or ventricular tachyarrhythmia. CONCLUSIONS: In our experience we found that oral administration of flecainide in a single dose of 400 mg is useful to unmask type 1 Brugada electrocardiographic pattern.

Electromagnetic interference with implantable cardiac pacemakers by video capsule.

BACKGROUND: Electromagnetic fields, such as those generated by cellular phones and metal detectors, may interfere with normal pacemaker function. However, it remains unclear whether the wireless capsule endoscope interacts with implanted pacemakers. This prospective study evaluated potential interactions between the M2A video capsule (Given Imaging, Yoknam, Israel) and implanted pacemakers. METHODS: A total of 100 consecutive patients (70 men, 30 women) with an implanted pacemaker (95 on bipolar mode) were studied. The testing was performed with a functional testing device (Test Cap) for the Given Diagnostic System that reproduces the effect of the video capsule by transmitting at exactly the same frequency. During continuous electrocardiographic monitoring and recording, 100 tests were carried out without changing the pacemaker settings. Those with a positive result were retested 1 week later. RESULTS: The 100 pacemakers evaluated in the study population included the following: 70 dual chamber (11 DDD, 56 DDDR, 3 VDD) and 30 ventricular inhibited (12 VVI, 18 VVIR). In 4 of the 100 patients, pacemaker interference (noise-mode function forcing a synchronous mode) was registered during the Test Cap operation. Three patients had a dual-chamber pacemaker, and one had a single-chamber pacemaker. The interference was reproducible in all cases 1 week later. None of the implanted pacemakers tested was affected by oversensing. CONCLUSIONS: Electromagnetic interferences with pacemakers from the M2A video capsule can occur, but this is without clinical significance. No potentially dangerous pacemaker inhibition was observed.