Left atrial wall thickness and outcomes of catheter ablation for atrial fibrillation in patients with hypertrophic cardiomyopathy

Purpose Catheter ablation of atrial fibrillation (AF) in patients with hypertrophic cardiomyopathy (HCM) is still challenging, and it is unclear whether the difficulty is caused by the hypertrophy of left atrial (LA) myocardial wall thickness. The objective of the study was to compare the LA wall thickness and AF ablation outcomes between patients with HCM and those without structural heart disease. Methods The present study enrolled 17 consecutive HCM patients (63+/-12 years) with drug-refractory AF and 34 control patients without any detectable heart disease, whose age, gender, type of AF, and LA dimension were matched to the HCM patients. The myocardial wall thickness of 11 distinct LA locations, measured using 64-slice computed tomography images, and AF ablation outcomes were compared between the two groups. Results The LA wall thickness did not differ at 9 of the 11 locations and was significantly thinner in the HCM patients than in the control patients at the mid-posterior wall (1.44+/-0.17 vs. 1.58+/-0.22, p=0.04) and infero-posterior wall (1.62+/-0.16 vs. 1.74+/-0.18, p=0.03). Although antiarrhythmic drugs were used more frequently in the HCM patients (p=0.008), the rate of maintaining sinus rhythm during the follow-up did not differ between the HCM and control patients (53 vs. 56 % after the initial ablation [log-rank p=0.78] and 82 and 88 % after the repeat procedure [log-rank p=0.35]). Conclusions The LA wall in the HCM patients with AF was not thicker than that of the matched patients without structural heart disease. Catheter ablation of AF showed favorable outcomes in both patient groups.