Left atrial (LA) enlargement is associated with atrial fibrillation (AF) recurrence after radiofrequency ablation (RFA). However, impact of right atrial (RA) size on outcomes after RFA is unclear.

Patients who underwent RFA of AF (n = 242, 197 men, 57 ± 11 years) were enrolled (159 paroxysmal [PaAF] and 83 persistent [PeAF]). Three-dimensional RA and LA volumes were measured before RFA with multidetector computed tomography and indexed to body surface area (RAVI and LAVI).

After a 3-month blanking period, 66 patients (27%) failed to maintain sinus rhythm during follow-up (556 ± 322 days). Despite similar clinical characteristics, LAVI was larger (77 ± 21 vs. 91 ± 27 ml/m², P < 0.001) and RAVI showed a trend to be greater (85 ± 26 vs. 92 ± 25 ml/m², P = 0.06) in patients with future recurrence than without recurrence. Additionally, patients with larger RA or LA experienced recurrences more frequently and earlier during follow-up (log rank, P < 0.05 for all). In Cox regression analysis, LAVI was independently associated with outcomes (10 ml/m² increase; HR: 1.22, 95% CI: 1.09–1.36, P < 0.001), whereas RAVI was not. In subgroup analysis, 25 PaAF patients (16%) experienced recurrence and both atrial volumes failed to predict the outcome independently, despite borderline significance of RAVI (10 ml/m² increase; HR: 1.21, 95% CI: 1.00–1.48, P = 0.05). Meanwhile, 41 patients (49%) in PeAF group experienced AF recurrence and LAVI was an independent prognosticator (10 ml/m² increase; HR: 1.19, 95% CI: 1.03–1.36).

RA size might affect the outcome after RFA in PaAF patients. LA enlargement, rather than RA size, influence outcomes after RFA, especially in PeAF.