Outcomes of Alcohol Septal Ablation in Patients With Severe Left Ventricular Outflow Tract Obstruction: A Propensity Score Matching Analysis

Background: The current ACC/AHA guidelines on hypertrophic cardiomyopathy (HCM) caution that alcohol septal ablation (ASA) might be less effective in patients with left ventricular outflow tract obstruction (LVOTO) >= 100 mm Hg.Methods: We used a multinational registry to evaluate the outcome of ASA patients according to baseline LVOTO.Results: A total of 1346 ASA patients were enrolled and followed for 5.8 +/- 4.7 years (7764 patient-years). The patients with baseline LVOTO >= 100 mm Hg were significantly older (61 +/- 14 years vs 57 +/- 13 years; P < 0.01), more often women (60% vs 45%; P < 0.01), and had a more pronounced HCM phenotype than those with baseline LVOTO < 100 mm Hg. There were no significant differences in the occurrences of 30-day major cardiovascular adverse events in the 2 groups. After propensity score matching (2 groups, 257 pairs of patients), the long-term survival was similar in both groups (P = 0.10), the relative reduction of LVOTO was higher in the group with baseline LVOTO >= 100 mm Hg (82 +/- 21% vs 73 +/- 26%; P < 0.01), but the residual resting LVOTO remained higher in this group (23 +/- 29 mm Hg vs 13 +/- 13 mm Hg; P < 0.01). Dyspnoea (NYHA functional class) at the most recent clinical check-up was similar in the 2 groups (1.7 +/- 0.7 vs 1.7 +/- 0.7; P = 0.85), and patients with baseline LVOTO >= 100 mm Hg underwent more reinterventions (P = 0.02).Conclusions: After propensity matching, ASA patients with baseline LVOTO >= 100 mm Hg had similar survival and dyspnoea as patients with baseline LVOTO < 100 mm Hg, but their residual LVOTO and risk of repeated procedures were higher.