BACKGROUND: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. METHODS: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). RESULTS: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/m(2), P<0.001) and RAVI showed a trend to be greater (85 ± 26 vs. 92 ± 25 ml/m(2), 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/m(2) 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/m(2) 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/m(2) increase; HR: 1.19, 95% CI: 1.03-1.36). CONCLUSIONS:RA size might affect the outcome after RFA in PaAF patients. LA enlargement, rather than RA size, influence outcomes after RFA, especially in PeAF.