Analysis Of Safety Of Atrial Fibrillation Ablation Under Lower Activated Clotting Times

Objective:To analyze the safety of atrial fibrillation(AF) ablation under lower activated clotting times(ACTs).Methods : Clinical data of 231 AF patients that underwent radiofrequency or cryoballoon ablation were collected. Averaged ACT during ablation procedure was calculated. According to the value of ACT, patients were divided into three groups: Averaged ACT <200 s, 200 ~ <250 s and ≥250 s. Embolic and bleeding complication rates of each group were analyzed. Then patients were categorized into bleeding group and non-bleeding group by the occurrence of bleeding complication. In this case-control study, univariate and multivariate logistic regression analysis were performed to identify the predictors of bleeding complications.Results: The number of patients with averaged ACT ranges of <200 s, 200 ~ <250 s and ≥250 s was 27(11.69%), 150(64.94%) and 54(23.38%) respectively. The mean CHADS2 score was 0.75±0.85. Complications occurred in 13(5.62%) patients totally, including 1(0.43%) embolism(stroke), 8(3.46%) bleeding [including 4(1.73%) cardiac tamponade and 4(1.73%) haematomas] and 4(1.73%) peripheral vascular complications. Both embolic and bleeding complications were observed in groups with averaged ACT of 200 ~ < 250 s and ≥250 s, while these two complications never occurred in <200 s group. Compared with 200 ~ <250 s group, bleeding complication rate of ≥250 s group was much higher(1.3% vs. 11.1%, P<0.01). Differences in other complications among the three groups were not significant. Multivariate logistic regression analysis indicated that the total procedural time(P<0.01, OR=1.025, 95%CI: 1.007~1.043), heparin bolus normalized for body weight(P<0.01, OR=1.067, 95%CI: 1.020~116) and averaged ACT(P<0.01, OR=1.065, 95%CI: 1.017~1.114) during ablation procedure were risk factors for bleeding complications.Conclusion: AF ablation is relatively safe with a target ACT of 200 ~ <250s for patients whose CHADS2 scores lower than 2, while bleeding risk should be taken into consideration when ACT appears to be over 250 s. Furthermore, the total procedural time, heparin bolus normalized for body weight and averaged ACT during ablation procedure prove to be predictors of bleeding complications.