P3778Long-term outcome of non-pharmacologial treatment of atrial fibrillation in hypertrophic cardiomyopathy: a large single-centre experience

Introduction Atrial fibrillation (AF) is common in hypertrophic cardiomyopathy (HCM) and is generally associated with a significant deterioration of clinical status. Non-pharmacological treatment such as surgical and catheter ablation has become an established therapy for symptomatic AF but in patients with HCM often having a chronically increased left atrial pressure and extensive atrial cardiomyopathy the long-term outcome is uncertain. Purpose The present study aimed to analyse the long-term outcome of AF ablation in HCM and the mechanism of recurrent atrial arrhythmias using high-density mapping systems. Methods A total of 65 patients (age 64.5±9.9 years, 42 (64.6%) male) with HCM undergoing AF ablation for symptomatic AF were included in our study. The ablation strategy for catheter ablation included pulmonary vein isolation in all patients and biatrial ablation of complex fractionated electrograms with additional ablation lines if appropriate. In patients with suspected atrial tachycardia (AT) high-density activation and substrate mapping were performed. A surgical ablation at the time of an operative myectomy for left ventricular outflow tract obstruction was performed in 8 (12.3%) patients. The outcome was analysed using clinical assessment, Holter ECG and continuous rhythm monitoring of cardiac implantable electric devices. Results Paroxysmal AF was present in 27 (41.6%), persistent AF in 37 (56.9%) and primary AT in 1 (1.5%) patients. The mean left atrial diameter was 54.1±12.5 ml. In 11 (16.9%) patients with AT high-density mapping was used to characterize the mechanism of the ongoing tachycardia. After 1.9±1.2 ablation procedures and a follow-up of 48.5±37.2 months, ablation success was demonstrated in 58.9% of patients. The success rate for paroxysmal and persistent AF was 70.0% and 55.8%, respectively (p=0.023). Of those patients with AT high-density mapping guided ablation was successful in 44.4% of patients. The LA diameter of patients with a successful ablation was smaller (52.2 vs. 58.1 mm; p=0.003). Conclusion Non-pharmacological treatment of AF in HCM is effective during long-term follow-up. Paroxysmal AF and a smaller LA diameter are favourable for successful ablation. In patients with complex AT the use of high-density mapping can guide ablation resulting in further ablation success in a reasonable number of patients.