AIMS: We analysed the impact of bundle branch block (BBB) and pacemaker (PM) implantation on symptoms and survival after alcohol septal ablation (ASA) in patients with hypertrophic cardiomyopathy (HCM).

METHODS AND RESULTS: Among 1416 HCM patients from the Euro-ASA registry, 58 (4%) patients had a PM and 64 (5%) patients had an implantable cardioverter-defibrillator (ICD) before ASA. At latest follow-up (5.0 ± 4.0 years) after ASA, 118 (8%) patients had an ICD and 229 (16%) patients had a PM. In patients without an implantable device prior to ASA 13% had a PM and 5% had an ICD implanted following ASA. New onset BBB was present in 44% (right BBB in 31%) of patients without previous BBB. At latest follow-up, we found no associations between BBB and New York Heart Association (NYHA) Class 3-4 [odds ratio (OR) 0.98, 95% confidence interval (CI) 0.63-1.51; P = 0.91] or Canadian Cardiovascular Society (CCS) Class 3-4 (OR 1.5, CI 0.32-6.7; P = 0.62), respectively, and no associations between PM and NYHA Class 3-4 (OR 1.2, CI 0.70-2.0; P = 0.52) or CCS 3-4 (OR 1.3, CI 0.24-6.6; P = 0.79), respectively. The survival after ASA was not reduced in patients with BBB [hazard ratio (HR) 0.73, CI 0.53-1.01; P = 0.06] or PM (HR 0.78, CI 0.52-1.17; P = 0.24).

CONCLUSIONS: Development of BBB or need for a PM after ASA in patients with obstructive HCM was not associated with inferior symptomatic outcome or reduced survival, thus concerns for the negative impact of impaired cardiac conduction on the clinical outcome after ASA were not confirmed.