July 15, 1995Circulation166 citations
View Full PaperCardioversion of Nonrheumatic Atrial Fibrillation
Key Result
Warfarin anticoagulation for a median of 4 weeks resulted in the complete resolution of 89% (95% CI, 73-100%) of atrial thrombi in patients with nonrheumatic atrial fibrillation.
Key Points
- This research aims to investigate the effects of warfarin anticoagulation on thrombus resolution in patients with nonrheumatic atrial fibrillation prior to cardioversion.
- Conducted serial transesophageal echocardiography in 14 patients after initial identification of atrial thrombi.
- All patients received warfarin anticoagulation for a median of 4 weeks.
- Monitored for clinical signs of thromboembolism post-treatment.
- 16 of 18 atrial thrombi (89%; 95% CI, 73% to 100%) resolved completely after warfarin treatment.
- No new thrombi were identified on follow-up study.
- No patients experienced clinical thromboembolic events during the study.
Study Design
Type
Observational (n=14)
Structured PICO
Does warfarin anticoagulation improve thrombus resolution in patients with nonrheumatic atrial fibrillation and atrial thrombi?
P
Population
14 patients with nonrheumatic atrial fibrillation and atrial thrombi identified on initial transesophageal echocardiography, followed for a median of 4 weeks on warfarin.
E
Exposure
Warfarin anticoagulation for a median of 4 weeks
O
Outcome
Thrombus resolution on follow-up transesophageal echocardiographysurrogate
Warfarin anticoagulation for 3 to 4 weeks before cardioversion in nonrheumatic atrial fibrillation leads to complete resolution of most atrial thrombi, explaining its mechanism of clinical benefit.
Abstract
BACKGROUND: The use of warfarin anticoagulation for several weeks before cardioversion results in a 90% reduction in the incidence of cardioversion-related thromboembolism. The mechanism of this benefit, however, is unknown; it has been widely attributed to organization and adherence of atrial thrombi, a finding observed among pathological studies of patients with rheumatic valvular disease. METHODS AND RESULTS: Serial transesophageal echocardiography was performed in 14 patients with nonrheumatic atrial fibrillation after identification of atrial thrombi on initial transesophageal study. All patients received warfarin anticoagulation and were followed clinically for signs of thromboembolism. Eighteen atrial thrombi were identified on initial transesophageal study, including 14 thrombi confined to the left atrial appendage, 2 in the body of the left atrium, 1 in the right atrial appendage, and 1 in the body of the right atrium. Thrombus size varied from 5 to 20 mm, and 6 were considered mobile. After a median of 4 weeks of warfarin, 16 of 18 atrial thrombi (89%; 95% CI, 73% to 100%) had completely resolved on transesophageal echocardiographic study. In addition, no new thrombi were identified on follow-up study, and no patient had a clinical thromboembolic event between studies. CONCLUSIONS: These data strongly support the hypothesis that among patients with nonrheumatic atrial fibrillation, the mechanism of clinical benefit with 3 to 4 weeks of warfarin before cardioversion is related to thrombus resolution and prevention of new thrombus formation rather than thrombus organization.