Incidence, Predictors, and Clinical Outcomes of Device-Related Thrombus in the Amulet IDE Trial.

Background: Device-related thrombus (DRT) following left atrial appendage occlusion (LAAO) can lead to adverse clinical outcomes. DRT rates and outcomes from randomized trials are limited.

Objectives: This analysis investigated the incidence, predictors, and clinical outcomes of DRT following LAAO in the Amulet IDE (AMPLATZER Amulet LAA Occluder Trial) trial.

Methods: Successful implants occurred in 903 patients with an Amulet occluder (dual occlusive mechanism device) and 885 patients with a Watchman device (single occlusive mechanism device). These patients were then followed through 18 months and DRT was assessed by transesophageal echocardiography.

Results: The overall incidence of DRT was 3.9% (n = 70) with 3.4% (n = 30) in dual occlusive mechanism device patients and 4.8% (n = 40) in single occlusive mechanism device patients. Most DRTs (n = 19 of 31) were identified early (≤45 days) on the dual occlusive mechanism device, whereas most of the DRTs (n = 31 of 42) were identified late (>45 days) on the single occlusive mechanism device. Strong predictors of DRT included atrial fibrillation at time of procedure (HR: 2.44; 95% CI: 1.42-4.22; P < 0.01), female sex (HR: 1.65; 95% CI: 1.01-2.71; P = 0.04), and older age (HR: 1.04; 95% CI: 1.01-1.08; P = 0.02). There were no stroke events following DRT in the dual occlusive mechanism device group and 3 stroke events following DRT in the single occlusive mechanism device group. Patients with DRT were at a greater risk for cardiovascular mortality compared with non-DRT patients (8.7% vs 3.9%; HR: 2.33; 95% CI: 1.01-5.39; P = 0.04).

Conclusions: Incidence of DRT following LAAO was low. Early DRTs are seen with the dual occlusive mechanism device and late DRTs are seen with the single occlusive mechanism device. Increased cardiovascular mortality risk in patients with DRT should be further investigated. (AMPLATZER Amulet LAA Occluder Trial; NCT02879448).