RESUMO
INTRODUCTION: The concept of a 3-month blanking period is widely accepted after the first radiofrequency catheter ablation (RFCA) session for atrial fibrillation (AF). We sought to investigate whether this phenomenon was also observed after a 2nd session, and which factors were related to it. METHODS AND RESULTS: We conducted a prospective observational study including all AF patients who underwent RFCA since 2010. The patients who underwent a second RFCA were followed without any antiarrhythmic drugs. Their clinical background, laboratory data, echocardiographic parameters, ablation procedures, and arrhythmia recurrences were analyzed. Recurrences were classified into early period recurrences (EPRs) and late period recurrences (LPRs) recorded within and after the first 3 months postablation, respectively. Among 925 patients who underwent an initial AF ablation, 2nd sessions were performed in 250 patients, and EPRs and LPRs occurred in 53 (21.2%) and 54 (21.6%) patients, respectively. Although EPRs were an independent predictor of LPRs (hazard ratio [HR], 8.01; 95% confidence interval [CI] 4.03-15.93, P < 0.001), 20 of the patients with EPRs (37.7%) did not experience LPRs, supporting the concept of a blanking period. Among 53 patients with EPRs, the E/E' ratio on echocardiography (HR, 1.156; 95% CI 1.00-1.33, P = 0.04) was an independent predictor of LPRs, while other parameters including the maximum serum C-reactive protein level after the session and the ablation procedure details were not. CONCLUSION: A 3-month blanking period was also applicable after the 2nd AF ablation session. This phenomenon was related to a lower left atrial pressure demonstrated by the E/E' ratio.