Background: The impact of antithrombotic therapy on coagulation system activation after left atrial appendage closure (LAAC) remains unknown. This study sought to compare changes in coagulation markers associated with short-term oral anticoagulation (OAC) versus antiplatelet therapy (APT) following LAAC.
Methods: Prospective study including 78 atrial fibrillation patients undergoing LAAC with the Watchman device. F1+2 (prothrombin fragment 1+2) and TAT (thrombin-antithrombin III) were assessed immediately before the procedure, and at 7, 30, and 180 days after LAAC.
Results: Forty-eight patients were discharged on APT (dual: 31, single: 17) and 30 on OAC (direct anticoagulants: 26, vitamin K antagonists: 4), with no differences in baseline-procedural characteristics between groups except for higher spontaneous echocardiography contrast in the OAC group. OAC significantly reduced coagulation activation within 7 days post-LAAC compared with APT (23% [95% CI, 5%-41%] versus 82% [95% CI, 54%-111%] increase for F1+2, P=0.007; 52% [95% CI, 15%-89%] versus 183% [95% CI, 118%-248%] increase for TAT, P=0.048), with all patients in both groups progressively returning to baseline values at 30 and 180 days. Spontaneous echocardiography contrast pre-LAAC was associated with an enhanced activation of the coagulation system post-LAAC (144 [48-192] versus 52 [24-111] nmol/L, P=0.062 for F1+2; 299 [254-390] versus 78 [19-240] ng/mL, P=0.002 for TAT). Device-related thrombosis occurred in 5 patients (6.4%), and all of them were receiving APT at the time of transesophageal echocardiography (10.2% versus 0% if OAC at the time of transesophageal echocardiography, P=0.151). Patients with device thrombosis exhibited a greater coagulation activation 7 days post-LAAC (P=0.038 and P=0.108 for F1+2 and TAT, respectively).
Conclusions: OAC (versus APT) was associated with a significant attenuation of coagulation system activation post-LAAC. Spontaneous echocardiography contrast pre-LAAC associated with enhanced coagulation activation post-LAAC, which in turn increased the risk of device thrombosis. These results highlight the urgent need for randomized trials comparing OAC versus APT post-LAAC.
Keywords: antithrombin III; atrial appendage; atrial fibrillation; prothrombin; thrombin.