Junctional rhythm during cryoablation for typical atrioventricular nodal reentrant tachycardia.

INTRODUCTION: Cryoablation is being used as an alternative to radiofrequency (RF) ablation for atrioventricular nodal reentrant tachycardia (AVNRT) owing to the lower risk of atrioventricular block (AVB) compared to RF ablation. Junctional rhythm often occurs during successful application of RF ablation for AVNRT. In contrast, junctional rhythm has rarely been reported to occur during cryoablation. This retrospective study evaluated the characteristics of junctional rhythm during cryoablation for typical AVNRT. METHODS AND RESULTS: This retrospective study included 127 patients in whom successful cryoablation of typical AVNRT was performed. Patients diagnosed with atypical AVNRT were excluded. Junctional rhythm appeared during cryofreezing in 22 patients (17.3%). These junctional rhythms appeared due to cryofreezing at the successful site in the early phase within 15 s of commencement of cooling. Transient complete AVB was observed in 10 of 127 patients (7.9%), and it was noted that atrioventricular conduction improved immediately after cooling was stopped in these 10 patients. No junctional rhythm was observed before the appearance of AVB. No recurrence of tachycardia was confirmed in patients in whom junctional rhythm occurred by cryofreezing at the successful site. CONCLUSION: Occurrence of junctional rhythms during cryoablation is not so rare and can be considered a criterion for successful cryofreezing. Furthermore, junctional rhythm may be associated with low risk of recurrent tachycardia.

Benefit of implantable cardioverter defibrillator use in Japanese patients based on modified MADIT-ICD benefit score.

AIMS: The MADIT-ICD benefit score is used to stratify the risk of life-threatening arrhythmia and non-arrhythmic mortality. We sought to develop an implantable cardioverter defibrillator (ICD) benefit-prediction score for Japanese patients with ICDs. METHODS: Patients who underwent ICD implantation as primary prophylaxis were retrospectively enrolled. Based on their MADIT-ICD benefit scores, we developed a modified MADIT-ICD benefit score adapted to the Japanese population. The primary endpoints were appropriate ICD therapy and all-cause death without appropriate ICD therapy (non-arrhythmic death). We used the Fine and Gray multivariate model and Cox proportional hazard regression to identify factors for adjusting the MADIT-ICD benefit-risk score specifically for the Japanese population. The scoring points for the original MADIT-ICD benefit score were adjusted to optimal points based on the multivariate analysis results in the population. RESULTS: The study enrolled 167 patients [age, 61.9 ± 12.3 years; male individuals, 138 (82.6%); cardiac resynchronization therapy, 73 (43.7%); ischaemic cardiomyopathy, 53 (31.7%)]. Fourteen patients received anti-tachycardia pacing (ATP) therapy, and 23 received shock therapy as the initial appropriate ICD therapy. Non-arrhythmic deaths occurred in 37 patients. The original MADIT-ICD benefit score could not stratify non-arrhythmic mortality in the Japanese population. The patients were reclassified into three groups according to the modified MADIT-ICD benefit score. The modified MADIT-ICD benefit score could effectively stratify the incidence of appropriate ICD therapy and non-arrhythmic mortality. In the highest-benefit group, the 10 year cumulative rates of appropriate ICD therapy and non-arrhythmic mortality were 56.8% and 12.9%, respectively (P < 0.01). In the intermediate-benefit group, these rates were 20.2% and 40.2% (P = 0.01). In the lowest-benefit group, the incidence of non-arrhythmic deaths was 68.1%, and no patient received appropriate ICD therapy. CONCLUSIONS: The modified MADIT-ICD benefit score may be useful for stratifying ICD candidates in the Japanese population.

Right ventricular systolic function as a predictor of appropriate ICD therapy.

BACKGROUND: Recent studies have shown that right ventricular dysfunction is associated with a significantly increased risk of sudden cardiac death. The purpose of this study was to evaluate the association of the right ventricular fractional area change (RVFAC) and appropriate implantable cardioverter-defibrillator (ICD) therapy to determine the cutoff value of the RVFAC. METHODS: Consecutive patients who underwent initial ICD implantations except those with hypertrophic cardiomyopathy, Brugada syndrome, and long QT syndrome were retrospectively enrolled. The primary endpoint was defined as any appropriate ICD therapy. The right ventricular dimensions and function on transthoracic echocardiography were measured for analysis. RESULTS: In total, 172 patients (60.3 ± 13.6 years, 131 males) were enrolled. Ninety patients received an ICD as a secondary prophylaxis. The mean LV ejection fraction and RVFAC were 38.3 ± 14.3% and 35.8 ± 8.8%, respectively. Regarding appropriate ICD therapy events, the best cutoff value of the RVFAC was 34.8%, while 74 patients had an RVFAC < 34.8%. Regarding the primary endpoint, the hazard ratio of a low RVFAC was 2.73 (95% CI 1.46-5.12, P < 0.01). In the multivariate analysis, a low RVFAC was an independent predictor of appropriate ICD therapy (HR: 3.40, 95% CI 1.74-6.64, P < 0.01). The secondary prophylactic cohort with a low RVFAC had the highest incidence of appropriate ICD therapy. Among the patients with RV dysfunction, the RVFAC normalized in 39% of patients during follow-up. This recovered RVFAC group had a significantly lower incidence of appropriate ICD therapy than the unrecovered RVFAC group (P = 0.043). CONCLUSION: A low RVFAC might be associated with increased appropriate ICD therapy.