Impact of catheter ablation on atrial fibrillation burden and symptoms in patients with hypertrophic cardiomyopathy

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Atrial Fibrillation (AF) is more common in patients with hypertrophic cardiomyopathy (HCM) and is often very symptomatic in this cohort. The impact of catheter ablation (CA) in this context is controversial with low success rates using the guideline mandated end-point of freedom from arrhythmia. Purpose To determine whether CA of AF in patients with HCM would be associated with a significant reduction in AF burden and symptoms. Methods Patients diagnosed with HCM undergoing CA of AF between February 2017 and June 2021 were identified from a prospective, single-centre registry. Patients with CIED in situ were selected. Patients were followed up for objective evaluation of symptom severity. Interval device interrogation and remote CIED monitoring was used to determine first AF/AT recurrence and percentage AF/AT burden on continuous rhythm monitoring 12-months before and after CA. Results Of 257 HCM patients undergoing CA of AF, 33 had CIEDs and were followed up for 32±15 months. The mean age was 56.4±10.2 years and 22 (67%) were male. The maximal wall thickness on echocardiography was 1.7±0.3cm and LA diameter was 4.8±0.9. The left ventricular ejection fraction was 50±15%. 17 (52%) patients had paroxysmal AF and 16 (48%) had persistent AF of which 6 (18%) were longstanding persistent AF. Mean AF burden prior to CA was 36.9±26.5% and 24 (73%) reported EHRA III-IV symptom severity. AF recurred in 27 (82%) patients with a median time to first recurrence of 8 (3-17) months. AF burden significantly reduced after index AF CA (27% (7,59) to 2% (0, 41)) (Z=-2.2, p= 0.03)) and reduced further when allowing for repeat procedures in 10 (30%) patients to 0% (0-30%). This represented a >50% relative reduction in 22 (67%) patients and >95% relative reduction in 16 (48%) patients. This correlated with a reduction in symptom score with 20 (60.6%) patients reporting a change of ≥1 EHRA class, and 20 (60.6%) patients reporting EHRA class I-IIa status at 12 months. A positive relationship was seen on regression analysis, with a 16.4% absolute reduction in AF burden associated with a reduction of one EHRA class. (R2= 0.206, F=7.5, p=0.01). Amongst the 24 (72%) patients who had an AF/AT recurrence after the final procedure who would conventionally be called failures by guideline definitions, 11 (45.8%) patients improved by ≥ 1 EHRA class and 11 (45.8%) were class I-IIa. Conclusion Although AF recurrence is common after CA in HCM patients, there is a significant reduction in AF burden and symptoms in a majority of patients. A more comprehensive evaluation of AF burden, symptoms, quality of life and impact on hard end-points is needed to determine the utility of CA in this context.