Background Observational data have suggested that performing radiofrequency catheter ablation of atrial fibrillation (AF) under therapeutic warfarin (’continuous warfarin’,CW) may reduce the periprocedural risk of complications,such as thromboembolic events,compared to warfarin discontinuation (DW) with periprocedural bridging with heparin.We systematically reviewed the available evidence on the impact of CW compared to DW on periprocedural complications of AF catheter ablation.Methods and Results We searched major web databases for studies on radiofrequency catheter ablation of AF under CW compared to DW with periprocedural bridging with heparin.Data on periprocedural complications were extracted.Results are expressed as odds ratio (OR) with its 95% confidence interval (CI).We identified 9 studies (1 large case series indirectly compared with the latest Worldwide Survey).A total of 27,402 patients were included in the analysis (6,400 undergoing ablation with CW).CW was associated with a striking decrease of thromboembolic complications (OR=0.10 [95% CI 0.05 to 0.23],P < 0.001) and minor bleeding complications (OR=0.38 [95% CI 0.21 to 0.71],P=0.002) compared to DW.CW also did not increase the risk of major bleeding (OR=0.67 [95% CI 0.31 to 1.43],P=0.30) including cardiac tamponade (OR=0.69 [95% CI 0.19 to 2.47],P=0.57).Conclusions There is highly consistent evidence from observational studies that a CW strategy during radiofrequency catheter ablation of AF reduces the risk of thromboembolic complications without increasing the risk of bleeding. Background Observational data have suggested that performed radiofrequency catheter ablation of atrial fibrillation (AF) under therapeutic warfarin (’continuous warfarin’, CW) may reduce the periprocedural risk of complications, such as thromboembolic events, compared to warfarin discontinuation (DW) with periprocedural bridging with heparin. We systematically reviewed the available evidence on the impact of CW catheter to DW on periprocedural complications of AF catheter ablation. Methods and Results We searched major web databases for studies on radiofrequency catheter ablation of AF under CW compared to DW with periprocedural bridging with Results identified were expressed as odds ratio (OR) with its 95% confidence interval (CI) .We identified 9 studies (1 large case series indirectly compared with the latest Worldwide Survey). A total of 27,402 patients were included in the analysis (6,400 undergoing ablation with CW) .CW was associated with a striking decrease of thromboembolic complications (OR = 0.10 [95% CI 0.05 to 0.23], P <0.001) and minor bleeding complications (OR = 0.38 [95% CI 0.21 to 0.71], P = 0.002) compared to DW.CW also did not increase the risk of major bleeding (OR = 0.67 [95% CI 0.31 to 1.43], P = 0.30) including cardiac tamponade (OR = 0.69 [95% CI 0.19 to 2.47], P = 0.57) .Conclusions There is is highly consistent evidence from observational studies that a CW strategy during radiofrequency catheter ablation of AF reduces the risk of thromboembolic complications without increasing the risk of bleeding.