Intensity of anticoagulation and risk of thromboembolism after elective cardioversion of atrial fibrillation

Abstract

Background Elective cardioversion (ECV) for atrial fibrillation (AF) is associated with a relatively low risk of thromboembolic complications. However, the optimal intensity of anticoagulation for ECV is unknown. We sought to assess the risk of thromboembolism in low (INR 2.0–2.4) vs. high (INR ≥ 2.5) therapeutic range in a large retrospective cohort study.

Methods This multi-centre “real world” study included 1424 ECVs in 1021 patients. The primary outcome was a stroke or a transient ischaemic attack (TIA) or a systemic embolus during the 30-day follow-up after ECV.

Results Altogether 4 (0.3%) strokes, 2 (0.1%) TIAs and 2 (0.1%) bleeds were detected during the 30-day follow-up after ECV. No systemic emboli were detected. There were 2 deaths (0.1%), one associated with a stroke. Median time to stroke/TIA was 4 (IQR 9.5) days and the median CHA2DS2-VASc-score was 2 (IQR 1.25) among patients with thromboembolic events. Mean INR at ECV was 2.7 (SD 0.54) in the study cohort. Patients with INR 2.0–2.4 at ECV had more thromboembolic events compared with patients with INR ≥ 2.5 (5/529 (0.9%) vs. 1/895 (0.1%), p = 0.03). Comprehensive postprocedural INR data was available for 733 (71.8%) patients and 1007 cardioversions. At least one subtherapeutic (< 2.0) INR value was detected within 21 days after 230 (22.8%) ECVs and this drop in INR level was associated with a higher risk for thromboembolic events compared with continuous therapeutic post-cardioversion anticoagulation (1.7% vs 0.3%, p = 0.03).

Conclusions Our results suggest that the intensity of periprocedural anticoagulation is associated with the risk of thromboembolic events after ECV.