Distinct mortality patterns and sudden cardiac death mechanisms in heart failure with a preserved ejection fraction.

Sudden cardiac death (SCD) is a leading cause of mortality in heart failure (HF), yet its incidence, mechanisms, and predictors in heart failure with preserved ejection fraction (HFpEF) remain poorly characterized. We conducted a prospective study of 2331 patients hospitalized for decompensated HF, stratifying them into HFpEF (n = 754), HF with mid-range ejection fraction (HFmrEF, n = 369), and HF with reduced ejection fraction (HFrEF, n = 1208). Over a median 25-month follow-up, 298 patients (12.8%) experienced SCD. HFpEF patients had the lowest SCD incidence (5.9%) compared to HFmrEF (13.8%) and HFrEF (16.7%) (p < 0.01). Asystole predominated in HFpEF SCD cases (52.9%), whereas ventricular tachyarrhythmias dominated in HFmrEF and HFrEF. In multivariate competing risk analysis, NYHA class III (cause-specific hazard ratio [csHR] 2.04, 95% CI 1.20-3.45, p < 0.01; subdistribution hazard ratio [sHR] 1.56, 95% CI 1.16-1.96, p = 0.01) and prolonged QTc interval > 480 ms (csHR 1.63, 95% CI 1.03-2.55, p = 0.01; sHR 1.57, 95% CI 1.04-2.38, p = 0.03) independently predicted SCD in patients with HFpEF. These findings reveal distinct SCD patterns in HFpEF and underscore the need for phenotype-specific risk stratification and prevention strategies.