Two-Year Outcomes of Primary Prophylactic Use of Defibrillators for Ischemic and Non-Ischemic Cardiomyopathy　- Propensity Score-Matched Analysis From the Nippon Storm Study.

BACKGROUND: In 2016, the DANISH study reported negative results regarding the efficacy of implantable cardioverter-defibrillators (ICDs) in patients with non-ischemic cardiomyopathy (NICM) and reduced left ventricular ejection fraction (LVEF). In this study we determined the efficacy of using ICDs for primary prophylaxis in patients with NICM.Methods and Results: We selected 1,274 patients with underlying cardiac disease who were enrolled in the Nippon Storm Study. We analyzed the data of 451 patients with LVEF ≤35% due to NICM or ischemic cardiomyopathy (ICM) who underwent ICD implantation for primary prophylaxis (men, 78%; age, 65±12 years; LVEF, 25±6.4%; cardiac resynchronization therapy, 73%; ICM, 33%). After propensity score matching, we compared the baseline covariates between groups: NICM (132 patients) and ICM (132 patients). The 2-year appropriate ICD therapy risks were 27.7% and 12.2% in the NICM and ICM groups, respectively (hazard ratio, 0.390 [95% confidence interval, 0.218-0.701]; P=0.002). CONCLUSIONS: This subanalysis of propensity score-matched patients from the Nippon Storm Study revealed that the risk of appropriate ICD therapy was significantly higher in patients with NICM than in those with ICM.

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.

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.