Background Left ventricular outflow tract obstruction (≥30 mm Hg at rest; LVOTO) is considered a possible risk of long-term outcomes in patients with hypertrophic cardiomyopathy (HCM). However, the influence of LVOTO on the occurrence of cardiovascular mortality events in patients after alcohol septal ablation (ASA) for obstructive HCM remains unresolved.

Methods We compared the outcomes of patients treated with ASA with residual LVOTO <30 mm Hg with those with residual LVOTO ≥30 mm Hg at the first postdischarge check-up (1–6 months after the procedure).

Results A total of 270 patients (60±12 years, median follow-up 5.1 years; 95% CI 4.5 to 5.9 years) treated with a single ASA were included; 208 (77%) and 62 (23%) patients had post-ASA LVOTO <30 and ≥30 mm Hg at the first postdischarge clinical check-up, respectively (LVOTO 13±6 vs 50±27 mm Hg; p<0.01). Freedom from cardiovascular mortality events at 1, 5 and 10 years were 99% (95% CI 96% to 100%) vs 94% (95% CI 85% to 98%), 95% (95% CI 89% to 97%) vs 80% (95% CI 66% to 89%) and 82% (95% CI 69% to 89%) vs 72% (95% CI 55% to 84%) (log-rank test, p<0.01), respectively. In multivariable analysis adjusted for age at ASA, sex, baseline LVOTO and baseline septum thickness, the independent predictors of cardiovascular mortality events were early postdischarge LVOTO ≥30 mm Hg (HR 2.95, 95% CI 1.26 to 6.91; p=0.01) and baseline septum thickness (HR 1.07, 95% CI 1.01 to 1.13; p=0.02).

Conclusions After ASA for obstructive HCM, LVOTO ≥30 mm Hg at the first postdischarge clinical check-up is associated with significantly higher occurrence of subsequent cardiovascular mortality events.