Impact of the right atrial substrate on arrhythmia recurrence following atrial fibrillation ablation

Abstract

Although it is recognised that left atrial remodelling contributes to the arrhythmogenic substrate in atrial fibrillation (AF), the involvement of the right atrium remains incompletely understood. Right atrial substrate perturbations may contribute to arrhythmia recurrence following AF catheter ablation, which primarily targets the left atrium. To evaluate right and left atrial structural, functional, and electrophysiological predictors of AF recurrence following ablation and determine whether right atrial substrate perturbations independently predict recurrence risk. In a multicentre, prospective, observational, cohort study, patients undergoing first-time AF ablation underwent pre-procedural cardiac magnetic resonance imaging (MRI) and intraprocedural bi-atrial electroanatomic mapping and electrophysiological assessment. Structural, functional, and electrophysiological parameters — including bi-atrial volume, ejection fraction, MRI-derived fibrosis burden, mean bipolar voltage, low voltage area, conduction velocity, wave collision percentage, and effective refractory period — were evaluated. Associations with arrhythmia recurrence were assessed using univariable Cox proportional hazards models for time to recurrence within 12 months excluding blanking period-only events. Significant predictors were examined in multivariable Cox models. Eighty-six patients were included, of whom 32 experienced arrhythmia recurrence. In univariable analysis, right atrial electroanatomic mapping parameters including mean bipolar voltage (HR 0.36, 95% CI 0.17–0.77, p=0.008), low voltage area percentage (HR 1.27, 95% CI 1.06–1.52, p=0.009) and wave collision percentage (HR 1.18, 95% CI 1.01–1.37, p=0.036) as well as left atrial low voltage area percentage were associated with recurrence (HR 1.15, 95% CI 1.03–1.28, p=0.016). In multivariable models adjusting each right atrial predictor for its corresponding left atrial parameter, mean right atrial voltage remained independently associated with recurrence (HR 0.33, 95% CI 0.12–0.90, p=0.031). Reduced right atrial bipolar voltage is independently associated with arrhythmia recurrence following first-time AF ablation after adjustment for left atrial bipolar voltage. These findings suggest that perturbations in the right atrial substrate may contribute to arrhythmia recurrence following ablation. Further studies are warranted to define the role of right atrial substrate assessment in risk stratification and tailored ablation strategies.