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Should all patients undergo transesophageal echocardiography before electrical cardioversion of atrial fibrillation?
R A Grimm1, W J Stewart, I W Black
1Department of Cardiology, Cleveland Clinic Foundation, Ohio 44195-5064.
Insights
Anticoagulant therapy for atrial fibrillation (AF) patients undergoing electrical cardioversion should last 4 weeks, even without thrombus. This strategy protects against embolization from pre-existing or post-cardioversion thrombus formation.
Area of Science:
- Cardiology
- Electrophysiology
- Thrombosis Research
Background:
- Management of anticoagulant therapy during electrical cardioversion for atrial fibrillation (AF) is debated.
- Inadequate studies and evolving use of transesophageal echocardiography (TEE) contribute to controversy.
Purpose of the Study:
- To investigate mechanisms of thrombus and embolism in AF patients undergoing electrical cardioversion.
- To propose modified anticoagulation management strategies based on new insights.
Main Methods:
- Review of recent investigations into thrombus formation mechanisms.
- Analysis of predisposing factors for thromboembolic events post-cardioversion.
- Evaluation of the role of transesophageal echocardiography (TEE).
Main Results:
- Both pre-existing thrombus and a post-cardioversion thrombogenic milieu can cause embolization.
- Therapeutic anticoagulation for 4 weeks is supported for AF patients with >2-day duration, regardless of TEE findings.
- TEE can guide early cardioversion if thrombus is absent or identify high-risk patients to postpone cardioversion.
Conclusions:
- A 4-week anticoagulation strategy post-cardioversion is recommended for AF patients.
- TEE's role is to facilitate early cardioversion or identify high-risk patients.
- A prospective randomized trial is needed to compare current versus TEE-guided strategies.
Abstract:
The management of anticoagulant therapy in patients with atrial fibrillation undergoing electrical cardioversion remains controversial, largely because of inadequate studies demonstrating risk or benefit, a relatively inconvenient anticoagulation management strategy and the increasing use of transesophageal echocardiography. Recent investigations into the potential mechanisms involved in the development of thrombus and systemic embolism in patients undergoing electrical cardioversion of atrial fibrillation may provide insight into underlying predisposing factors, with subsequent modification of management strategies. Conventional wisdom suggests that preexisting thrombus is responsible for thromboembolic events after cardioversion. However, development of a thrombogenic milieu after cardioversion, particularly in the left atrial appendage, may also be an important predisposing factor. To protect against both potential mechanisms of embolization, these data support therapeutic anticoagulation for all patients with atrial fibrillation of > 2 days in duration from the time of, as well as after cardioversion for a total of 4 weeks, undergoing cardioversion, even in the absence of thrombus on echocardiography. Therefore, the role of transesophageal echocardiography in this setting should be to enable early cardioversion if atrial thrombus is excluded and to identify high risk patients with atrial thrombi so as to postpone cardioversion and avoid the risk of embolization. Ultimately, however, a controlled, randomized and prospective clinical trial will be required to compare conventional management with a transesophageal echocardiography-guided strategy.