RESUMO
Background: Current guidelines recommend proceeding with cardioversion, without the explicit need for preprocedural transesophageal echocardiography (TEE), in patients compliant with oral anticoagulation for at least 3 weeks. The relevance of these guidelines remains unclear in those undergoing repeat cardioversion. Case summary: A 66-year-old male with a history of atrial fibrillation (AF) and a left atrial appendage occlusion (LAAO) device, compliant with apixaban, presented with dyspnea and lightheadedness. He was cardioverted into sinus rhythm, 10 days before symptom onset, with TEE unremarkable at the time. An ECG revealed that the patient converted back into AF and a repeat cardioversion was scheduled. At the patient's request, a TEE was obtained, revealing a new 2 cm×1 cm thrombus in the left atrium above the WATCHMAN device. Cardioversion was canceled and the patient was hospitalized for AF management. Discussion: Cardioverted patients are at risk for thrombus formation due to atrial stunning, a transitory dysfunction of the atrial appendage and atrium, which occurs immediately after cardioversion and can persist for several weeks. The likelihood of a thrombus is further propagated by individual risk factors for stroke. Conclusion: Anticoagulation does not eliminate the risk of thrombus formation in those with increased risk factors for stroke. Further studies are warranted to assess the need for routine TEE, after cardioversion, in those with stroke risk factors on anticoagulation or who have LAAO.