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Stroke and Thromboembolism After Cardioversion
Study Questions:
What is the risk of thromboembolism after cardioversion within 48 hours of atrial fibrillation (AF) onset in patients with and without anticoagulation?
Methods:
Using a single-center database of cardioversion procedures between 1996 and 2012, patients undergoing cardioversion within 48 hours of AF onset were identified. Rates of major thromboembolic events within 30 days following cardioversion were calculated and stratified according to anticoagulation status at the time of cardioversion.
Results:
Among 567 cardioversions in 484 patients without therapeutic anticoagulation (mean CHA2DS2-VASc score 2.3 ± 1.7), six had neurologic events (1.06%). Each of those patients was treated with aspirin therapy alone. Among 898 cardioversions in 709 patients on therapeutic anticoagulation (mean CHA2DS2-VASc score 2.6 ± 1.7, p = 0.017), two neurologic events occurred (0.22%, odds ratio, 4.8; p = 0.03). Both of these patients experienced their stroke after anticoagulation had been discontinued following the cardioversion. No thromboemboliuc events occurred in patients with a CHA2DS2-VASc score <2 or in patients with postoperative AF.
Conclusions:
The authors concluded that in patients with acute-onset AF, the odds of a thromboembolic complication within 30 days of cardioversion were nearly 5 times higher in patients who did not receive anticoagulation therapy. However, no events occurred in patients with low CHA2DS2-VASc scores, supporting the use of that risk score in determining the need for anticoagulation in acute-onset AF patients planning cardioversion therapy.
Perspective:
This single-study registry highlights the importance of risk stratification among AF patients undergoing cardioversion. While the absolute number of thromboembolic events was low across the entire population (eight events over 1,465 cardioversions), there seems to be a concentration of events among intermediate and high stroke-risk patients (CHA2DS2-VASc ≥2). Other similar studies have demonstrated low thromboembolic risk for acute-onset AF patients undergoing cardioversion (J Am Coll Cardiol 2013;62:1187-92). A prospective study testing the safety of CHA2DS2-VASc scoring to determine the need for systemic anticoagulation prior to cardioversion in acute-onset AF is warranted before this practice is strongly endorsed by guidelines.
Keywords: Anticoagulants, Arrhythmias, Cardiac, Atrial Fibrillation, Aspirin, Electric Countershock, Risk, Secondary Prevention, Stroke, Thromboembolism, Vascular Diseases
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