Thromboembolic complications after cardioversion of acute atrial fibrillation: the FinCV (Finnish CardioVersion) study.

Objectives: This study sought to explore the incidence and risk factors of thromboembolic complications after cardioversion of acute atrial fibrillation.

Background: Anticoagulation therapy is currently recommended after cardioversion of acute atrial fibrillation in patients with risk factors for stroke, but the implementation of these new consensus-based guidelines has been slow.

Methods: A total of 7,660 cardioversions were performed in 3,143 consecutive patients with atrial fibrillation lasting <48 h in 3 hospitals. For this analysis, embolic complications were evaluated during the 30 days after 5,116 successful cardioversions in 2,481 patients with neither oral anticoagulation nor peri-procedural heparin therapy.

Results: There were 38 (0.7%; 95% confidence interval [CI]: 0.5% to 1.0%) definite thromboembolic events (31 strokes) within 30 days (median 2 days, mean 4.6 days) after cardioversion. In addition, 4 patients suffered transient ischemic attack after cardioversion. Age (odds ratio [OR]: 1.05; 95% CI: 1.02 to 1.08), female sex (OR: 2.1; 95% CI: 1.1 to 4.0), heart failure (OR: 2.9; 95% CI: 1.1 to 7.2), and diabetes (OR: 2.3; 95% CI: 1.1 to 4.9) were the independent predictors of definite embolic events. Classification tree analysis showed that the highest risk of thromboembolism (9.8%) was observed among patients with heart failure and diabetes, whereas patients with no heart failure and age <60 years had the lowest risk of thromboembolism (0.2%).

Conclusions: The incidence of post-cardioversion thromboembolic complications is high in certain subgroups of patients when no anticoagulation is used after cardioversion of acute atrial fibrillation. (Safety of Cardioversion of Acute Atrial Fibrillation [FinCV]; NCT01380574).