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[Transesophageal echocardiography in patients with atrial fibrillation, candidates for cardioversion: usefulness and
E Antonielli1, A Pizzuti, N Gandolfo
1Divisione di Cardiologia, Ospedale SS. Annunziata, Savigliano, CN.
Insights
Transesophageal echocardiography (TEE) cannot rule out thromboembolic events after electrical cardioversion (CV) for atrial fibrillation (AF). Anticoagulant therapy is recommended for all patients undergoing CV, even if TEE shows no thrombi.
Area of Science:
- Cardiology
- Medical Imaging
- Electrophysiology
Background:
- Thromboembolic complications following electrical cardioversion (CV) for atrial fibrillation (AF) are linked to dislodged left atrial thrombi.
- Transesophageal echocardiography (TEE) has been used to identify patients suitable for CV without anticoagulation.
- Recent reports indicate embolic events post-CV even in patients with no thrombus evidence on TEE.
Purpose of the Study:
- To determine if the absence of thrombi or prethrombotic conditions justifies electrical CV without anticoagulation.
- To assess the role of spontaneous echo contrast and left atrial appendage dysfunction in predicting embolic risk.
- To evaluate the safety of foregoing anticoagulant therapy based on TEE findings.
Main Methods:
- Seventy-four patients with AF undergoing CV were evaluated using monoplane TEE.
- Anticoagulation was omitted if TEE showed no thrombi or spontaneous echo contrast and good left atrial appendage function (peak flow > 20 cm/sec).
- Patients not meeting criteria or with identified thrombi/dysfunction received standard anticoagulant therapy.
Main Results:
- Forty-six patients (62%) underwent CV without anticoagulation.
- Twenty-eight patients received warfarin therapy.
- One patient without anticoagulation experienced cerebral embolism 24 hours post-CV, despite a TEE showing no thrombus or spontaneous echo contrast, but revealed low left atrial appendage flow velocity.
Conclusions:
- Excluding thrombi or prethrombotic conditions via TEE does not eliminate thromboembolic risk after CV in AF patients.
- Left atrial appendage function can be transiently impaired post-CV, promoting a thrombogenic state and embolic events.
- Therapeutic anticoagulation is recommended during and after cardioversion for atrial fibrillation.
Background:
Thromboembolic complications after electrical cardioversion (CV) of atrial fibrillation (AF) have been attributed to the dislodgment of preexistent left atrial thrombus during the resumption of atrial contraction. Transesophageal echocardiography (TEE) has been used to identify patients without thrombus, who potentially could undergo CV without anticoagulation. However, embolic events after CV in patients without evidence of thrombus on TEE have recently been reported.
Aim Of The Study:
To evaluate if absence of thrombi or prethrombotic conditions such as spontaneous echo contrast or left atrial appendage disfunction can justify electrical CV without anticoagulant therapy.
Methods:
Seventy-four patients with AF and candidates for CV underwent monoplane TEE. Patients were cardioverted without anticoagulation in case of: 1) absence of thrombus and/or spontaneous echocardiographic contrast and 2) good visualization of left atrial appendage, with a well defined peak blood flow velocity greater than 20 cm/sec. In all other cases, patients underwent anticoagulant therapy which started 3 weeks before CV and continued for 4 weeks afterwards.
Results:
Forty-six patients, without thrombus or "prethrombotic" conditions, did not receive anticoagulation, while 28 followed traditional therapy with warfarin. Four patients with a thrombus in the left atrial appendage were identified: 1 died of cerebral embolism 3 days after the beginning of anticoagulation, in another one CV was definitely deferred because of the persistence of thrombus after 1 month of warfarin therapy. One patient, with left atrial appendage disfunction, died suddenly after 5 days of anticoagulation. Two patients reverted spontaneously in sinus rhythm. Two patients refused electrical CV. The remaining 67 patients underwent electrical CV which was successful in 56 of them. Cerebral embolism occurred 24 hours after CV in one patient who did not receive anticoagulation. Repeat TEE soon after embolism showed absence of thrombus or spontaneous echo contrast, but the presence of low flow velocity in the left atrial appendage.
Conclusions:
In patients in AF candidates for CV, exclusion of thrombi or prethrombotic conditions by TEE does not exclude the risk of thromboembolic events and the need for anticoagulant therapy. Left atrial appendage function can be stunned or impaired immediately after CV, favouring a thrombogenic milieu and subsequent embolic events. Therapeutic anticoagulation at the time of as well as after cardioversion is actually recommended.