Introduction
Atrial fibrillation (AF) is commonly seen in patients with hypertrophic cardiomyopathy (HCM) (~20%).1Catheter ablation (CA) is a reasonable therapeutic approach in selected patients with HCM and AF (class IIa indication, Level of Evidence B).2 Studies addressing the efficacy of AF CA in patients with HCM are limited and have demonstrated worst long-term outcomes compared to non-HCM patients.3-7 Persistent AF, female gender, age, New York Heart Association (NYHA) functional class, LA enlargement, and left ventricle (LV) outflow tract obstruction have been proposed as predictors of AF recurrence following catheter ablation in this specific population.3-5 Pulmonary vein (PV) isolation only appears insufficient to improve the long-term arrhythmia survival in HCM patients, possibly due to extensive LA remodeling.6
Among AF patients undergoing catheter ablation, atrial tissue fibrosis assessed by delayed enhancement magnetic resonance imaging was independently associated with arrhythmia recurrence.8The presence of LA cardiomyopathy estimated by high-density electroanatomical mapping (EAM) has been associated with AF relapse following catheter ablation.9,10 Data regarding the EAM LA substrate in patients with HCM and AF are missing. In this high-density EAM study, we evaluated for the first time the extent of LA fibrosis and its impact on catheter ablation outcomes in patients with HCM and AF.