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Atrial thrombi resolution after prolonged anticoagulation in patients with atrial fibrillation
Insights
Warfarin therapy before cardioversion for atrial fibrillation significantly reduced atrial thrombi in most patients. This suggests thrombus lysis, not organization, is the primary mechanism, but follow-up imaging is crucial.
Area of Science:
- Cardiology
- Thrombosis Research
Background:
- Cardioversion for atrial fibrillation in nonanticoagulated patients carries a risk of thromboembolism.
- Prolonged anticoagulation with warfarin before cardioversion significantly reduces this risk.
- The presumed mechanism for reduced thromboembolism is atrial thrombi organization.
Purpose of the Study:
- To evaluate the efficacy of prolonged warfarin therapy in resolving atrial thrombi before cardioversion.
- To investigate the mechanism by which anticoagulation reduces cardioversion-related thromboembolism.
Main Methods:
- Transesophageal echocardiography (TEE) was used to diagnose atrial thrombi in 123 patients with atrial fibrillation.
- Patients received oral warfarin for a median of 4 weeks.
- TEE was repeated to assess thrombus resolution.
Main Results:
- Atrial thrombi were identified in 9% of patients, primarily in the left atrial appendage.
- After 4 weeks of warfarin, 81.8% of thrombi completely resolved.
- No thromboembolic events occurred between TEE studies.
Conclusions:
- Prolonged warfarin therapy effectively resolves atrial thrombi in the majority of patients.
- Thrombus lysis, rather than organization, appears to be the main mechanism of thromboembolism reduction.
- Follow-up TEE is essential to confirm thrombus resolution before cardioversion due to potential persistence.
Background:
Cardioversion of atrial fibrillation in nonanticoagulated patients may be associated with clinical thromboembolism. Prolonged anticoagulation with warfarin before cardioversion of atrial fibrillation produces a marked reduction of cardioversion-related thromboembolism. The benefit of anticoagulant therapy is generally believed to be due to atrial thrombi organization.
Patients And Methods:
Transesophageal echocardiography (TEE) is highly accurate for diagnosis of atrial thrombi and gives the possibility to serially evaluate the effects of anticoagulant therapy. One hundred twenty-three patients with atrial fibrillation lasting longer than 2 days underwent TEE before cardioversion. An atrial thrombus was identified in 11 patients (9%), and was always confined to the left atrial appendage. TEE was repeated after a median of 4 weeks of oral warfarin. Atrial thrombus had completely resolved in 9 of 11 patients (81.8%; 95% CI, 48.2 to 97.7%); in two patients, clot was still present. No patient had clinical thromboembolism between the two TEE studies.
Conclusions:
In the population of our study, a prolonged course of warfarin therapy was associated with resolution of atrial thrombi in the majority of patients. According to these data, the mechanism of thromboembolism reduction with 4 weeks of anticoagulation before cardioversion in patients with atrial fibrillation seems to be related mainly to thrombus lysis rather than organization. Due to the possibility of thrombus persistence even after prolonged anticoagulation, follow-up with TEE before cardioversion is necessary to document thrombus resolution.