Catheter ablation of atrial fibrillation in patients with hypertrophic cardiomyopathy

Abstract

Purpose: Atrial fibrillation (AF) is common in patients with hypertrophic cardiomyopathy (HCM) and known to predict adverse outcome. Radiofrequency catheter ablation represents a promising option to improve symptoms and outcome of these patients. The purpose of this study was to evaluate the long term effects of catheter ablation in AF patients with HCM. Methods: Twenty-five consecutive patients (19 male, age 53.4±8.0 years) with HCM undergoing pulmonary vein (PV) isolation with or without additional left atrial roof, mitral isthmus or cavotricuspid isthmus linear ablations for drug-refractory AF (16 paroxysmal AF) composed the HCM group of this study. Fifty non-HCM patients (38 male, age 53.5±8.3 years, 32 paroxysmal AF) matched for age, sex and types of AF were used as the control group. Ablation strategy used in control group was similar to that utilized in HCM group. Baseline characteristics, cardiac functional improvement and success rate of AF ablation during follow-up were compared. Results: All patients underwent ablation successfully without major complication. The left atrium (LA) was significantly larger in patients with HCM (47.38±7.51 vs. 40.36±7.98 mm in control group, P=0.001). Other baseline characteristics were comparable between two groups. AF-related symptoms were assessed by the European Heart Rhythm Association (EHRA) score which was 3.04±0.68 in HCM group and 2.54±0.68 in control group (P=0.003). Integrated long term follow-up data (3.39±1.17 years) were available in 20 patients of HCM group and 44 patients of non-HCM group. After an average of 1.1 procedures, sinus rhythm was retained in 9/20 (45%) patients with HCM and 32/44 (72.7%; p=0.032) patients without HCM. In HCM group, 8/9 patients were free from AF recurrence off anti-arrhythmic drug. Among patients in whom mitral isthmus (MI) linear ablation were performed, bidirectional isthmus block was achieved in 50% (4/8) of patients with HCM, comparing to 70.6% (12/17) in control group. After ablation, patients with HCM who maintained sinus rhythm showed remarkable improvement of NYHA cardiac functional categorization (1.1±0.3 vs. 1.6±0.5, P=0.035). Conclusions: AF-related symptoms are more severe in patients with HCM. Success rate of AF ablation remained low in this cohort. Restoration of sinus rhythm in HCM patients is associated with significant cardiac functional improvement.