The optimal antithrombotic therapy (AT) after left atrial appendage closure (LAAC) is debated. We assessed the impact of intensive vs nonintensive AT on the incidence of device-related thrombus (DRT) based on whether the device implantation was classified as optimal or suboptimal.

This study included patients who underwent successful LAAC in 9 centers. Patients were classified according to the quality of device implantation: optimal (proximal implant without ≥3mm peridevice leak) or suboptimal (distal implant and/or ≥3mm peridevice leak). Postimplant AT was classified as either intensive (dual antiplatelet therapy, anticoagulants, or a combination of both) or nonintensive (no AT or a single antiplatelet therapy). The primary endpoint was the incidence of DRT between the 6th and 12th weeks postprocedure.

A total of 1225 patients underwent LAAC, with 757 (61.8%) achieving optimal device implantation and 468 (38.2%) classified as suboptimal. After a median follow-up of 20 months, the incidence of DRT in the optimal implant group was 2.6% with intensive AT and 3.7% with nonintensive AT (P=.38). In the suboptimal implant group, the incidence of DRT increased to 11.2% with intensive AT and 15.5% with nonintensive AT (P=.19). On multivariate analysis, suboptimal implantation (HR, 4.51; 95%CI, 2.70-7.54, P<.001) but not intensive AT (HR, 0,66; 95%CI, 0.40-1.07, P=.09) emerged as an independent predictor of DRT.

The incidence of DRT after LAAC was higher in patients with suboptimal device implantation. In patients with optimal implantation, the incidence of DRT was low and similar between nonintensive and intensive AT strategies. Large, randomized trials are warranted to confirm these results.