Long-Term Predictors of Thromboembolic Events in Nonvalvular Atrial Fibrillation Patients Undergoing Electrical Cardioversion

Abstract

Background:Patients with nonvalvular atrial fibrillation (AF) who undergo electrical cardioversion (ECV) tend to be younger and have less comorbidity. Long-term anticoagulation after ECV should be based on thromboembolic risk. We sought to study the long-term incidence of thromboembolic events (TE), factors related to TE and compare the predictive value of the CHADS₂and CHA₂DS₂-VASc scores in this particular population.Methods and Results:From January 2008 to June 2012, 571 ECV were performed in 406 consecutive patients with nonvalvular AF. Risk factors for TE and factors related to anticoagulation therapy after ECV were registered. During a follow-up of approximately 2 years, the annual incidence of TE was 1.9%. Factors associated with TE were: poor quality anticoagulation control (hazard ratio [HR]: 2.91; 95% confidence interval [CI]: 1.10–7.80; P=0.03), cessation of anticoagulation after ECV (HR: 8.80; 95% CI: 3.11–25.10; P<0.001), age ≥65 years (HR: 13.65; 95% CI: 1.74–107.16; P=0.01), CHADS₂score (HR: 1.59; 95% CI: 1.10–2.29; P=0.01) and CHA₂DS₂-VASc score (HR: 1.67; 95% CI: 1.30–2.22; P<0.001). Both risk scores predicted TE [c-statistic for CHADS₂: 0.68 (95% CI: 0.62–0.74; P=0.005), for CHA₂DS₂-VASc: 0.75 (95% CI: 0.70–0.80; P<0.001)]. Based on c-statistics, the predictive accuracy of CHA₂DS₂-VASc was superior (difference between areas: 0.064±0.031; P=0.0403).Conclusions:Important determinants of long-term occurrence of TE after ECV were related to anticoagulant therapy (poor quality anticoagulation and cessation of this therapy over follow-up). The CHA₂DS₂-VASc score successfully predicts TE after ECV, having better predictive accuracy than the CHADS₂score. (Circ J 2016; 80: 605–612)