Incidence and Predictors of Late Complete Heart Block After Alcohol Septal Ablation Treatment of Hypertrophic Obstructive Cardiomyopathy

ObjectivesThis study was designed to identify the incidence of late complete heart block (CHB) first identified at least 48hours post alcohol septal ablation (ASA). BackgroundSeptal reduction with ASA is a therapeutic option for patients with symptomatic hypertrophic obstructive cardiomyopathy (HCM). CHB, resulting from the septal infarct, is a known complication with a reported incidence of 9-22%. The incidence of CHB more than 48hours post-procedure is unknown. MethodsConsecutive patients who underwent ASA were analyzed and clinical characteristics associated with late CHB were assessed. Late CHB was defined as first identification of CHB more than 48hours after ASA. ResultsFrom 2002-2013, 145 subjects underwent 168 ASA procedures and were followed for a mean of 3.2 +/- 2.3 years. The incidence of late CHB was 8.9% (15/168 ASA procedures). Heart block occurred from 48hours to 3-years post-procedure. In a multivariable model, patients with any CHB were more likely to have had multiple ASA procedures (OR 4.14; 95% CI: 1.24, 13.9; P<0.05) and high resting and provoked left ventricular outflow tract (LVOT) gradient assessed by catheterization (OR per 10mmHg gradient 1.14; 95% CI: 1.0, 1.20; P<0.05). After multivariable adjustment, only a high provokable LVOT gradient remained an independent predictor of late CHB (OR per 10mmHg gradient 1.14 [95% CI 1.02-1.29]). ConclusionsLate CHB is a common complication of ASA for treatment of symptomatic HCM. Post-discharge electrocardiographic surveillance for atrioventricular conduction disease should be considered after ASA, especially for those with a high provokable LVOT gradient. (J Interven Cardiol 2015;28:90-97)