Comparative effectiveness of existing medical therapy for atrial fibrillation in hypertrophic cardiomyopathy (AF-HCM)
S Huang, M Liu, P Nair, M Perez, V ParikhAbstract
Background
Atrial fibrillation in hypertrophic cardiomyopathy (AF-HCM) is a unique clinical entity occurring in ~25% of HCM patients, associated with high symptom burden and adverse outcomes. Rhythm control is the preferred AF-HCM treatment approach, including cardioversion with or without anti-arrhythmic drug (AAD) therapy and AF ablation. However, there is limited data on clinical covariates associated with non-ablative therapy selection, and little is known about its effectiveness in AF-HCM, hindering design of comparative effectiveness studies and AF-HCM trials.
Purpose
To describe clinical characteristics of AF-HCM patients receiving non-ablative therapies and evaluate their effectiveness in preventing AF recurrence at a single academic center.
Methods
Time to AF recurrence after direct current cardioversion (DCCV) was assessed using the Stanford Center for Inherited Cardiovascular Disease database. Patients with AF-HCM undergoing successful DCCV between July 2006 and June 2025 were included, with diagnoses confirmed by HCM specialists. Chart review assessed medications, AF and ablation history, genetic testing, and imaging results. Patients were grouped by post-DCCV outpatient therapy: amiodarone, non-amiodarone AADs (sotalol, dofetilide, dronedarone), or non-AAD therapy (e.g., beta-blockers, calcium channel blockers). The primary outcome was survival free of AF recurrence and clinical characteristics were compared at baseline.
Results
Of 136 patients, 45 received amiodarone, 48 non-amiodarone AADs (33 sotalol, 7 dofetilide, 8 dronedarone), and 43 non-AAD therapy. 31 had AF ablation pre-DCCV (12 amiodarone, 11 non-amiodarone AAD, 8 non-AAD). Overall AF recurrence was 44% at 90 days and 64% at 1 year (Figure 1A). At baseline, non-amiodarone AAD patients were more likely to have prior AF (p=0.006) and severely enlarged left atria (>48 mL/m²; p=0.043) than other groups. Age, sex, and genotype did not differ across treatments. Unadjusted survival analysis trended toward higher recurrence in non-amiodarone AADs at 1 year (Figure 1B). However, there was no significant difference between treatment groups when adjusting for age, sex, atrial size, and prior AF history (non-amiodarone AAD vs. amiodarone: 1.07 [0.55,2.11], p=0.84; non-amiodarone AAD vs. non-AAD: 0.56 [0.28,1.1], p=0.10).
Conclusions
Short-term AF recurrence on non-ablative therapy is high, regardless of therapeutic strategy. Amiodarone and non-AAD strategies were more frequent in patients with smaller atria and lower prevalence of prior AF compared to non-amiodarone AADs, reflecting use later in disease course. Use of amiodarone as often as non-AADs in earlier AF-HCM may reflect a preference for immediate stabilization, followed by other AADs with fewer long-term side effects, especially in inpatient settings. These results highlight the distinctive recurrence profile of AF-HCM and demonstrate the need for improved non-ablative strategies in this high-risk population.Figure 1For image description, please refer to the figure legend and surrounding text.