Clinical outcome of left atrial ablation for paroxysmal atrial fibrillation is related to the extent of radiofrequency ablation

Background The exact mechanism of eliminating atrial fibrillation (AF) by catheter ablation techniques is not known. We investigated whether the extent of atrial damage conferred by radiofrequency lesions is a predictor of success after ablation, regardless of the method employed for ablation. Methods Ninety consecutive patients with paroxysmal AF subjected to ostial-antral pulmonary vein isolation (n=41) or circumferential (n=49) catheter ablation were studied. Results At 1 year follow-up, 16 out of 41 patients (39%) with ostial-antral ablation and 16 out of 49 patients (32.6%) with circumferential ablation had AF recurrences (p=0.5). The mean duration of radiofrequency ablation lesions was statistically significantly shorter in patients with recurrence of AF compared to those with sinus rhythm 1 year after ablation (22.3 +/- 4.2 min vs. 27.2 +/- 4.5 min, respectively, p value < 0.001). Radiofrequency ablation time was inversely associated with the risk of recurrence of AF 1 year after ablation and this relationship remained even after adjustment for potential confounding factors such as age, sex, left atrial size, and type of ablation technique (ostial-antral or circumferential; HR = 0.80, 95% CI: 0.72-0.87, p < 0.001). Conclusiosn Duration of radiofrequency energy delivery is an independent predictor of clinical outcome at 1 year follow-up both among patients undergoing circumferential as well as ostial-antral ablation.