When to perform transesophageal echocardiography (TEE) before cardioversion?

When to Perform Transesophageal Echocardiography Before Cardioversion

Transesophageal echocardiography (TEE) should be performed before cardioversion in patients with atrial fibrillation or atrial flutter of ≥48 hours or unknown duration who have not been adequately anticoagulated for the preceding 3 weeks. 1

Decision Algorithm for TEE Before Cardioversion

AF/Flutter Duration ≥48 Hours or Unknown Duration:

1. Standard Approach (No TEE needed):

   • Anticoagulate with warfarin (INR 2-3) or NOAC (dabigatran, rivaroxaban, edoxaban, or apixaban) for at least 3 weeks before cardioversion
   • Continue anticoagulation for at least 4 weeks after cardioversion
   • Long-term anticoagulation decision based on thromboembolic risk (CHA₂DS₂-VASc score)

2. TEE-Guided Approach (When to use TEE):

   • When immediate cardioversion is desired without waiting 3 weeks
   • Patient has not been anticoagulated for the preceding 3 weeks
   • Procedure: Perform TEE to exclude left atrial thrombi, then proceed with cardioversion if no thrombi identified
   • Anticoagulation must be initiated before TEE and maintained for at least 4 weeks after cardioversion 1

3. When Thrombus is Detected on TEE:

   • Postpone cardioversion
   • Continue anticoagulation for 4-12 weeks
   • Consider repeat TEE before attempting cardioversion again 1

AF/Flutter Duration <48 Hours:

1. High Thromboembolic Risk (CHA₂DS₂-VASc ≥2 in men, ≥3 in women):

   • Administer anticoagulation (heparin, LMWH, factor Xa inhibitor, or direct thrombin inhibitor) before cardioversion
   • Continue long-term anticoagulation after cardioversion 1, 2
   • TEE generally not required

2. Low Thromboembolic Risk (CHA₂DS₂-VASc 0 in men, 1 in women):

   • May consider cardioversion without TEE or prolonged anticoagulation 1, 2
   • Short-term perioperative anticoagulation may be considered

Special Considerations

• Hemodynamic Instability: For patients requiring immediate cardioversion due to hemodynamic instability, proceed with cardioversion without delay and initiate anticoagulation as soon as possible 1

• Enhanced TEE Accuracy: Contrast-enhanced TEE improves interpretability and facilitates more definitive exclusion of atrial thrombi compared to conventional TEE 3

• Atrial Stunning: Even after successful cardioversion, transient atrial dysfunction ("stunning") can occur, which may promote new thrombus formation. This justifies the recommendation for at least 4 weeks of post-cardioversion anticoagulation regardless of TEE findings 4

• Risk Factors for Thrombus: Patients with decreased left atrial appendage flow velocity (≤0.3 m/s) and moderate-to-marked spontaneous echo contrast on TEE have higher risk of thrombus formation 5, 3

Potential Pitfalls

1. Relying solely on TEE without anticoagulation: Even when TEE shows no thrombus, anticoagulation should be initiated before cardioversion and continued for at least 4 weeks afterward due to the risk of post-cardioversion atrial stunning 1, 4

2. Assuming short-duration AF is always safe: Recent evidence suggests that even AF of 12-48 hours duration carries thromboembolic risk, especially in older patients (>75 years) and women 1

3. Neglecting long-term anticoagulation decisions: The decision for anticoagulation beyond 4 weeks should be based on the patient's thromboembolic risk profile (CHA₂DS₂-VASc score), not on the apparent success of cardioversion 1, 2

4. Inadequate TEE technique: Standard TEE may yield inconclusive results in some patients; contrast enhancement can significantly improve diagnostic accuracy and reduce the rate of uncertain findings 3