BACKGROUND: The optimal number of septal branches to target during initial alcohol septal ablation (ASA) for hypertrophic obstructive cardiomyopathy (HOCM) remains a subject of debate. It is unclear whether to proceed with ASA of additional septal branches if a satisfactory hemodynamic effect has not been achieved following ablation of the first branch. METHODS: Using propensity score matching analysis, we compared patients who achieved satisfactory outcomes after ASA of a single septal branch with those in whom additional branches were ablated. RESULTS: A total of 457 patients were included in the study, with a median follow-up of 5.61 years (interquartile range 2.08-10.91 years). Propensity score matching identified 92 pairs (184 patients), divided into the single-ablated-branch and more-ablated-branches groups. No significant differences were found in the incidence of major cardiovascular adverse events within the first 30 days between the two groups. Similarly, there were no differences in long-term outcomes between the matched single-ablated-branch and multiple-ablated-branches groups regarding all-cause mortality (3.77 vs.2.90 deaths per 100 patient-years, log-rank p = 0.649), re-intervention rates (12 % vs. 8 %
log-rank p = 0.345), left ventricular outflow gradient (14 ± 13 mmHg vs. 16 ± 15 mmHg
p = 0.209), or NYHA functional class (1.7 ± 0.6 vs. 1.6 ± 0.7
p = 0.629). CONCLUSIONS: In both short- and long-term follow-ups, ASA targeting single or multiple septal branches showed comparable efficacy and safety in patients with hypertrophic obstructive cardiomyopathy.