Left atrial appendage thrombi despite oral anticoagulation in transthyretin amyloid cardiomyopathy patients undergoing electrical cardioversion for atrial fibrillation or - flutter.

Background: Patients with cardiac amyloidosis undergoing direct current electrical cardioversion (DCCV) are at risk of left atrial appendage thrombus (LAAT). We investigated LAAT formation rates, success rates, and long-term recurrence rates in transthyretin amyloid cardiomyopathy (ATTR-CM) patients. Methods: ATTR-CM patients scheduled to undergo DCCV were included in the study. LAAT exclusion was performed utilizing transesophageal echocardiography or computed tomography. Results: A total of 62 (1.35 per patient) DCCVs were recorded among 46 patients (77 ± 6.5 years, 89 % male) with ATTR-CM. In 39 DCCVs, LAAT exclusion was performed (62.9 %). In total, 10 DCCVs (16.1 %) were canceled due to (I) spontaneous conversion to sinus rhythm (n = 2, 5.1 %) or (II) definitive/suspected LAAT (n = 8, 20.5 %). Of these, five patients with LAAT had been receiving sufficient doses of oral anticoagulants for more than three weeks prior to DCCV. The immediate success rate was 92.3 %, and 3-month rhythm control was achieved in 27 (62.8 %) procedures. Notably, one stroke event was recorded two months following DCCV. Conclusion: A high rate of left atrial appendage thrombus was observed in ATTR-CM, leading to DCCV cancellation in 20.5% of patients. Despite a high immediate success rate (92.3%), sustained sinus rhythm control was achieved in only 62.8% following DCCV. These findings advise using TEE or CT prior to DCCV to exclude LAAT in ATTR-CM patients, even in those with oral anticoagulation.