We assessed the influence of interventricular septal thickness (IVSd) on the clinical outcome and survival after alcohol septal ablation (ASA) in patient with hypertrophic cardiomyopathy.Methods and Results—
We analyzed 531 patients with hypertrophic cardiomyopathy (age: 56±14 years, men 55%) treated with ASA. Survival status was obtained 7.9±4.0 years after ASA. Baseline IVSd was inversely associated with survival (hazard ratio [HR] for 1 mm increment, 1.13; confidence interval, 1.05–1.21; P<0.001) after adjustment for age, sex, body mass index, and ASA-performing center. Compared with patients with baseline IVSd <20 mm, patients with baseline IVSd ≥25 mm had reduced survival (HR, 5.0; CI, 2.1–12), whereas patients with baseline IVSd 20 to 24 mm had similar survival (HR, 1.4; CI, 0.7–2.8). Baseline IVSd was not correlated with New York Heart Association class, Canadian Cardiology Society class, or syncope. Clinical outcome was assessed 0.6±0.6 years after ASA. IVSd was not related to left ventricular outflow tract gradient reduction at rest (P=0.883) or during Valsalva maneuver (P=0.885). The proportion of patients in New York Heart Association class 3 to 4 was reduced from 86% to 10%; in Canadian Cardiology Society class 3 to 4 from 26% to 2%; and with syncope from 25% to 2%. There were no correlations between baseline IVSd and New York Heart Association class (P=0.067), Canadian Cardiology Society class (P=0.106), or syncope (P=0.426) after ASA.Conclusions—
ASA had equal effects on left ventricular outflow tract gradients and symptoms throughout the spectrum of septal hypertrophy. Severe septal hypertrophy before ASA remained a marker of reduced survival after ASA with a 5-fold increased risk of all-cause mortality in patients with baseline IVSd >25 mm compared with patients with baseline IVSd <20 mm.