Prevalence of atrial thrombi in patients with atrial fibrillation/flutter and subtherapeutic anticoagulation prior to cardioversion

Aims: Thromboembolism may complicate electrical cardioversion (ECV) of atrial fibrillation/flutter (AF). The use of 3 weeks of warfarin before ECV results in a substantial reduction of thromboembolic complications. Nevertheless, in patients scheduled for ECV subtherapeutic INR levels are common. We sought to assess the prevalence and the predictors of atrial thrombi in patients affected with sustained AF in whom subtherapeutic INR values were detected in the 3 weeks preceding scheduled ECV. Methods and results: Forty-one patients with persistent AF and ≥3 weeks warfarin anticoagulation who exhibited subtherapeutic INR values in the last 3 weeks underwent a transoesophageal echocardiogram (TOE) before a scheduled ECV. A left atrial appendage (LAA) thrombus was diagnosed on TOE in four patients (9.8%). Patients with thrombus had lower INR values (1.45±0.09 vs 1.72±0.20; p = 0.0068), lower LAA emptying velocities (13.75±4.5 vs 25.86±12.4 cm/s; p = 0.0313) and higher prevalence of atrial smoke (100 vs 37.8%, p = 0.03). Conclusions: Subtherapeutic levels of anticoagulation before elective ECV of AF may expose patients to post-ECV thromboembolic sequelae, especially in patients with lowest INR values. Current recommendations of a full course of therapeutic anticoagulation before ECV of persistent AF should be firmly observed.