Late device-related thrombus after left atrial appendage closure following early antithrombotic discontinuation: the paradox of complete sealing

Background Device-related thrombus (DRT) after left atrial appendage closure (LAAC) can occur. Objective To evaluate late/very-late DRT after an institutional early "all-off" strategy guided by complete sealing (peri-device leak [PDL]=0). Methods We analyzed 106 consecutive successful LAAC procedures; 103 patients had evaluable imaging at 45 days (≥45 days). Per protocol, antithrombotics were discontinued at 45 days and/or 6 months if imaging showed PDL=0 and no DRT. Landmark analyses in patients free of 45-day DRT (n=101) compared late/very-late DRT (6–12 months) between all-off and continued-therapy groups. Results DRT occurred in 6/103 patients (5.8%): 2 at 45 days and 4 at 6–12 months. Late/very-late DRT occurred in 4/33 (12.1%) in the all-off group versus 0/68 (0.0%) in the continued-therapy group (p=0.010). A sensitivity analysis restricted to patients with PDL=0 and no 45-day DRT (n=44) showed a consistent direction (4/28 vs 0/16; p=0.280). Among patients with PDL=0 and no 45-day DRT who continued direct oral anticoagulants (n=8), the primary reason was recent ischemic stroke <6 months (6/8, 75%). Conclusion Reliance on PDL=0 alone to guide early complete withdrawal may be insufficient in selected patients; findings are hypothesis-generating.