Thrombus Formation After Left Atrial Appendage Occlusion With the Amplatzer Amulet Device

This study sought to define the ideal post-procedural anticoagulant regime and to systematically study the incidence of device-related thrombus.

Left atrial appendage occlusion (LAAo) is an alternative to life-long oral anticoagulation in selected patients with atrial fibrillation.

This study included 24 atrial fibrillation patients (ages 79 ± 8 years; 75% male, CHA₂DS₂VASc [Congestive Heart Failure, Hypertension, Age ≥75 Years, Diabetes Mellitus, Previous Stroke or Transient Ischemic Attack or Thromboembolism, Vascular Disease, Age 65 to 74 Years. Sex] score: 4.3 ± 1.5, HAS-BLED [Hypertension, Abnormal Renal and Liver Function, Stroke, Bleeding, Labile International Normalized Ratio, Elderly, Drugs or Alcohol] score: 3.6 ± 0.8) after LAAo with the use of the Amplatzer Amulet system. Dual antiplatelet therapy for 3 months was prescribed in 95.6% of the cases.

Transesophageal echocardiography identified a high rate of device adherent thrombi (16.7%, n = 4 of 23) after a mean of 11.0 ± 8.2 weeks. Thrombus formation occurred under dual antiplatelet therapy (3 of 4) or clopidogrel monotherapy (1 of 4). When compared with patients without thrombi, echocardiography showed higher degrees of spontaneous echo contrast grades within the LAA (3.0 ± 1.0 vs. 1.3 ± 1.1), lower LAA peak emptying velocities (17.5 ± 5.0 cm/s vs. 48.3 ± 21.1 cm/s), and decreased left ventricular function (39 ± 10% vs. 50 ± 13%) in patients with device-related thrombus. All thrombi were observed within the untrabeculated region of the LAA ostium between the left upper pulmonary vein ridge and the occluder disc, indicating suboptimal LAA occlusion.

Device-related thrombus is a frequent finding after LAAo with the Amplatzer Amulet device (St. Jude Medical, St. Paul, Minnesota). Our results emphasize the need for an optimized post-LAAo anticoagulation regimen, a revised implantation strategy, and possibly modified patient selection criteria.