Electrophysiological Substrate and Ablation Outcomes in Atrial Fibrillation With Hypertrophic Cardiomyopathy: A
Umair Abrar1, Fazal Ghaffar2, Muhammad Zuhaid3
1Orthopaedic and Medical Institute (Pvt) Ltd. Karachi Pakistan.
Insights
Patients with hypertrophic cardiomyopathy and atrial fibrillation (HCM-AF) exhibit a more problematic atrial substrate, leading to poorer catheter ablation outcomes compared to lone AF patients. Left atrial low-voltage area burden significantly predicts recurrence after ablation.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Arrhythmias
Background:
- Atrial fibrillation (AF) is a common arrhythmia in hypertrophic cardiomyopathy (HCM).
- The electrophysiological substrate driving AF recurrence post-ablation in HCM patients is not well understood.
- This study compares atrial substrate and ablation outcomes in HCM-AF patients versus lone AF controls.
Purpose of the Study:
- To compare the atrial electrophysiological substrate between HCM-AF patients and lone AF controls.
- To evaluate catheter ablation outcomes, specifically freedom from recurrence, in these two groups.
- To identify predictors of AF recurrence in HCM-AF patients.
Main Methods:
- A multicenter retrospective study involving 143 HCM-AF patients and 143 propensity-score-matched lone AF controls.
- Left atrial (LA) electroanatomic voltage mapping and intracardiac electrophysiological variables were assessed.
- AF inducibility and 12-month freedom from recurrence post-ablation were primary endpoints.
Main Results:
- HCM-AF patients showed significantly greater LA low-voltage area (LVA) burden, wider atrial effective refractory period (AERP) dispersion, and higher AF inducibility.
- Twelve-month freedom from recurrence was lower in HCM-AF patients (51.7%) compared to lone AF controls (73.9%).
- LVA burden, HCM diagnosis, non-paroxysmal AF, and AERP dispersion independently predicted recurrence.
Conclusions:
- HCM-AF is characterized by a more arrhythmogenic atrial substrate, resulting in inferior ablation outcomes.
- LA LVA burden is a key predictor of AF recurrence in HCM-AF patients.
- Electrophysiological substrate phenotyping can aid in risk stratification for HCM-AF patients undergoing ablation.
Background:
Atrial fibrillation (AF) is the most common sustained arrhythmia in hypertrophic cardiomyopathy (HCM), yet the intracardiac electrophysiological substrate underlying recurrence following catheter ablation remains poorly characterized. We compared the atrial substrate and ablation outcomes between HCM-AF patients and propensity-score-matched lone AF controls.
Methods:
This multicenter retrospective study was conducted across three tertiary centers in Pakistan (2015-2023). Of 841 screened patients, 143 HCM-AF patients were matched 1:1 with 143 lone AF controls on 14 covariates. Left atrial (LA) electroanatomic voltage mapping, intracardiac electrophysiological variables, and AF inducibility were compared. Primary endpoints were LA low-voltage area (LVA) burden, AF inducibility, and 12-month freedom from recurrence post-ablation.
Results:
HCM-AF patients had greater LVA burden (29.7% ± 17.4% vs. 11.8% ± 9.7%, p < 0.001), wider AERP dispersion (41.3 ± 15.7 vs. 18.6 ± 9.4 ms, p < 0.001), and higher AF inducibility (81.8% vs. 58.7%, p < 0.001). Among 261 ablated patients, 12-month freedom from recurrence was 51.7% in HCM-AF versus 73.9% in lone AF (p = 0.001). LVA burden (aHR 1.41 per 10% increase), HCM diagnosis (aHR 2.19), non-paroxysmal AF (aHR 1.88), and AERP dispersion ≥ 30 ms (aHR 1.67) independently predicted recurrence. Latent class analysis identified three EP phenotype clusters with divergent outcomes: 81.7%, 61.4%, and 31.9% recurrence-free survival (p < 0.001). Complication rates were comparable (4.7% vs. 2.2%, p = 0.33).
Conclusion:
HCM-AF is associated with a more arrhythmogenic atrial substrate and inferior ablation outcomes compared with lone AF. LVA burden is the strongest predictor of recurrence. EP substrate phenotyping may enable meaningful risk stratification in this population.
