Low Incidence of Procedure-Related Major Adverse Cardiac Events After Alcohol Septal Ablation for Symptomatic Hypertrophic Obstructive Cardiomyopathy

Background: Alcohol septal ablation (ASA) is a catheter-based intervention that has been used as an alternative to surgical myectomy in highly symptomatic patients with hypertrophic obstructive cardiomyopathy (HOCM). However, clinically relevant complications can result, including death and complete heart block (CHB) associated with syncope or resuscitation. This study was designed to evaluate the incidence of major ASA-related adverse cardiac events. Methods: This international multicentre retrospective study included 421 patients in 8 European centres who were treated using ASA from April 1998 to January 2011. Clinical and echocardiographic follow-up (3-6 months) was completed in 394 patients (94%). Results: ASA led to a significant reduction in symptoms and outflow gradients, with 0.7% mortality. A total of 70 patients (17%) experienced mostly transient CHB during and after the procedure; in 30% of them, CHB occurred or recurred later than 24 hours after ASA. Ninety-seven percent of CHB occurred up to the fifth day after ASA. Permanent pacemakers for CHB were implanted in 35 patients (8%). Multivariate analysis identified intraprocedural bundle branch block and age as independent predictors of CHB. Conclusions: The results of the multicentre study demonstrate that ASA appears safe and efficacious, with low early mortality. The most frequent major complication after ASA was CHB (17%), which occurred late or was recurrent in almost one-third of these patients; 8% of patients required permanent pacemaker implantation. Independent predictors of CHB development were intraprocedural bundle branch block and age. Difficulty in predicting CHB should lead to close post-procedural monitoring and hospital stays lasting at least 5 days.