Antithrombotic therapy and device healing after left atrial appendage occlusion with Watchman FLX Pro: a single-center real-world cohort study

OBJECTIVES: The authors sought to determine whether discharge antithrombotic regimen (dual antiplatelet therapy [DAPT] vs low-dose direct oral anticoagulant [DOAC] monotherapy) is independently associated with computed tomography (CT)-detected high-grade hypoattenuated thickening (HAT), an imaging correlate of device-related thrombus, and with early clinical outcomes following WATCHMAN FLX Pro (Boston Scientific) implantation. METHODS: A single-center retrospective analysis of 427 consecutive patients undergoing attempted WATCHMAN FLX Pro implantation (July 2024-October 2025) was conducted. After excluding 10 patients with screen failure and 17 on alternative antithrombotic regimens, 400 patients (263 DAPT, 137 low-dose DOAC) were included. The primary endpoint was high-grade HAT on 4-month surveillance cardiac CT. Secondary endpoints were appendage patency, peridevice leak (PDL), incomplete neoendocardial coverage, and 180-day clinical outcomes. RESULTS: Surveillance CT was performed in 322 of 400 patients (80.5%). High-grade HAT occurred in 12/213 patients on DAPT (5.6%) vs 1/109 patients on DOAC (0.9%; P = .046); 92.3% of high-grade HAT cases were in the DAPT group. DAPT remained independently associated with high-grade HAT on multivariable analysis (adjusted odds ratio, 7.43; 95% CI, 1.01-54.44; P = .048). Appendage patency, PDL, and incomplete neoendocardial coverage were similar between groups. Through 180 days, stroke, bleeding, and mortality did not differ significantly by regimen. CONCLUSIONS: In this real-world WATCHMAN FLX Pro cohort, low-dose DOAC monotherapy was associated with a markedly lower risk of CT-detected high-grade HAT than DAPT, without an observed increase in bleeding or stroke. Anticoagulation during the early post-implant healing period may mitigate thrombus formation more effectively than antiplatelet therapy. Randomized trials are needed to confirm these findings.