Short-Term Anticoagulation Versus Dual Antiplatelet Therapy for Preventing Device Thrombosis Following Left Atrial Appendage Closure: The ANDES Randomized Clinical Trial

BACKGROUND: The optimal antithrombotic treatment after transcatheter left atrial appendage closure (LAAC) remains to be determined. The objective of this trial was to compare anticoagulation and antiplatelet therapy for preventing device-related thrombosis (DRT) after LAAC. METHODS: This was a prospective multicenter international randomized trial comparing 2 different antithrombotic strategies for preventing DRT after LAAC in patients with nonvalvular atrial fibrillation. Patients were randomized (1:1) to receive direct oral anticoagulants (DOACs) or dual antiplatelet therapy (DAPT; aspirin+clopidogrel) for 60 days. Patients underwent transesophageal echocardiography at 60 days, and the images were analyzed in a central echocardiography laboratory by experienced echocardiographers blinded to the allocated treatment. The primary outcome was DRT as determined by transesophageal echocardiography 60 days after LAAC in patients receiving the allocated treatment at the time of transesophageal echocardiography (per-protocol analysis). The safety outcome included all-cause mortality, stroke, bleeding, or site-reported DRT within 60 days after LAAC in all randomized patients (intention-to-treat analysis). RESULTS: A total of 510 patients (mean age 77±9 years, 35% women) were included between October 2018 and May 2025, and 253 and 257 patients were randomized to the DOAC and DAPT groups, respectively. Of these, 399 patients underwent transesophageal echocardiography and were receiving the allocated treatment at 60 days after LAAC. The primary outcome occurred in 3 patients (1.5%) in the DOAC group compared with 8 patients (4.1%) in the DAPT group (difference, −2.7% [95% CI, −6.0% to 0.6%]; P =0.110). The safety outcome occurred in 52 patients (22.5%) in the DOAC group compared with 82 patients (34.9%) in the DAPT group (difference, −12.4% [95% CI, −20.6% to −4.2%]; P =0.003), and differences were mainly driven by a lower rate of bleeding events in the DOAC group (44 patients [17.4%] versus 64 patients [24.9%]; difference, −7.5% [95% CI, −14.6% to −0.4%]; P =0.038). CONCLUSIONS: The use of DOACs after LAAC failed to reduce DRT compared with DAPT, but it was associated with an improved safety profile. The results of this study should be interpreted with caution because of statistical power issues related to the narrower-than-expected between-group differences and will need confirmation in future larger studies. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03568890.