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 can occur. OBJECTIVE: This study aimed to evaluate late/very-late DRT after an institutional early "all-off" strategy guided by complete sealing (peridevice leak [PDL] 0). METHODS: We analyzed 106 consecutive successful left atrial appendage closure procedures; 103 patients had evaluable imaging at 45 days (≥45 days). Per protocol, antithrombotic agents were discontinued at 45 days and/or 6 months if imaging showed PDL of 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 of 103 patients (5.8%): 2 at 45 days and 4 at 6-12 months. Late/very-late DRT occurred in 4 of 33 (12.1%) in the all-off group vs 0 of 68 (0.0%) in the continued-therapy group (P = .010). A sensitivity analysis restricted to patients with PDL of 0 and no 45-day DRT (n = 44) showed a consistent direction (4 of 28 vs 0 of 16; P = .280). Among patients with PDL of 0 and no 45-day DRT who continued direct oral anticoagulants (n = 8), the primary reason was recent ischemic stroke at <6 months (6 of 8; 75%). CONCLUSION: Reliance on PDL of 0 alone to guide early complete withdrawal may be insufficient in selected patients; findings are hypothesis generating.