MD Undergraduate University of British Columbia Markham, Ontario, Canada
Background: Patients with hypertrophic cardiomyopathy (HCM) face a 4–6-fold increased risk of atrial fibrillation (AF), a condition that worsens disease progression, elevates stroke risk, and is associated with worse outcomes. Despite this burden, evidence to guide treatment—particularly catheter ablation—remains limited. Optimal patient selection is critical to demonstrate efficacy and avoid unnecessary interventions. This study compares baseline characteristics and outcomes of HCM patients with AF who underwent catheter ablation versus those who did not to inform referral patterns and evaluate outcomes.
METHODS AND RESULTS: This retrospective cohort analysis included 1,375 HCM patients followed at the British Columbia HCM Clinic (April 2015-August 2024). Among 337 (24.5%) patients with documented AF, 53 (15.7%; 34 males) underwent catheter ablation, while 284 (84.3%; 164 males) did not. Ablation patients were younger at diagnosis (mean age 58±13 years vs. 62±19 years, p=0.11). Follow-up was comparable between ablation patients, (12.43±9.76) and non-ablation patients (9.9±9.08). Baseline structural and clinical characteristics were similar between groups, including age, weight, comorbidities, symptom burden, left atrial size, LVOT obstruction, maximal LV wall thickness, and other echocardiographic parameters. Rates of septal reduction therapy (SRT) were similar: 14 (26%) vs. 84 (29.6%) non-ablation patients. There were no significant differences in the rate of heart failure hospitalizations (15%; 8 ablation vs. 42 non-ablation patients), or cardiac arrests (3.8% ablation vs. 4.2% non-ablation). Rates of implantation of pacemakers (20.7% vs. 13%, p=0.14) and defibrillators (41.5% vs. 32%, p=0.21) was comparable, while CRT implantation was more common in the ablation group (11.3% vs. 4.2%, p=0.046). Patients undergoing ablation had higher AV node ablation rates (15% ablation, 9.4% non-ablation, p=0.00016). Despite prior studies suggesting benefits from ablation, this study found no statistically significant differences in clinical outcomes. This includes ischemic stroke (1.89% ablation, 9.86% non-ablation), and hemorrhagic stroke (0% ablation, 2.46% non-ablation). Individuals with ablations were more likely to have cardioversions for AF (56.60% ablation, 29.93% non-ablation).
Conclusion: This study highlights the challenge in selecting which HCM patients should undergo atrial fibrillation ablation and demonstrates an overall lack of improved clinical outcomes despite similar baseline demographics and characteristics. The results underscore the need for ongoing research into the role of atrial fibrillation ablation for patients with HCM. Our ongoing investigations will seek to determine if there are patient subgroups that derive benefit, as well as to investigate and compare ablation strategies. Future studies looking at ablation safety and efficacy using different modalities will also benefit from optimal patient selection criteria.
