Outcome of Primary Prevention Implantable Cardioverter Defibrillator Therapy According to New York Heart Association Functional Classification.

We aimed to assess if the outcome of primary prevention implantable cardioverter defibrillators (ICDs) without cardiac resynchronization therapy is dependent on New York Heart Association (NYHA) class. Among the participants of Défibrillateur Automatique Implantable-Prévention Primaire (DAI-PP; NCT01992458) multicenter cohort study, 155 patients in NYHA class I, 504 in NYHA class II, and 188 in NYHA class III had a QRS width <120 ms and were implanted with an ICD without cardiac resynchronization therapy and, thus, were eligible for the purpose of this analysis. Total and specific mortalities and the incidence of appropriate therapies were assessed for every NYHA. During 2,606 patient-years (3.1 ± 2.1 years), 104 (12.3%) subjects died and 188 (22.2%) experienced appropriate therapies. After adjustment, overall mortality increased with NYHA class (adjusted hazard ratio [HR] 1.63, 95% confidence interval [CI] 1.11 to 2.41, p = 0.014), driven by an increase in cardiovascular death. Conversely, incidence of appropriate ICD intervention was comparable among the 3 NYHA groups (NYHA class I 7.43, NYHA class II 7.91, and NYHA class III 12.10 per 100 patient-years; HR 1.19, 95% CI 0.89 to 1.59, p = 0.231). Incidence of ICD-unresponsive sudden death was very low and also comparable (NYHA class I 0.22, NYHA class II 0.36, and NYHA class III 0.83 per 100 patient-years (HR 6.34, 95% CI 0.32 to 124.49, p = 0.224). No significant differences were observed in the other specific modes of death. In conclusion, although patients in NYHA class III have higher overall mortality, they experience a comparable incidence of appropriate ICD therapies. The low incidence of ICD-unresponsive sudden death in all assessed NYHA classes also supports the efficacy of ICDs, irrespective of NYHA class.