Reducing the Risk of Device-Related Thrombosis Following LAA Closure

Dual antiplatelet therapy (DAPT) and new oral anticoagulation (NOAC) appear to have similar safety and device-related thrombosis (DRT) occurrence compared with warfarin and aspirin in real-world left atrial appendage closure (LAAC) registries, but more research is needed to further elucidate the role of antiplatelet therapy post-LAAC, according to an analysis published in the Journal of the American College of Cardiology Interventions.

In this contemporary review, investigators analyzed the options and rationale of antithrombotic therapy and associated DRT post-LAAC. In the PROTECT-AF (WATCHMAN Left Atrial Appendage System for Embolic Protection in Patients With Atrial Fibrillation) randomized controlled trial, investigators aimed to better understand the endothelialization process post-LAAC.

At 3 time points, the histopathology of the hearts of 9 dogs was studied. At 90 days, the fabric membrane was covered in fibrous tissue pannus with a monolayer of endothelial-like cells covering a healthy neoendocardium. Postmortem studies were conducted on the hearts of humans who had been implanted with the WATCHMAN device; gross and histopathologic findings were similar to those in the dogs at 90 days post-implantation. The timeline for complete endothelialization in humans has not been studied.

Researchers also analyzed the risks of DRT and real-world usage of non-warfarin regimens post-LAAC. DAPT is the most commonly used, with studies showing a DRT incidence of 4% post-WATCHMAN and a thromboembolic event rate of 2.3% per year in patients contraindicated to OAC.

Researchers reviewed the complication of DRT according to the antithrombotic regimen used. DRT continues to be associated with higher thromboembolic risks, and device imaging surveillance should be routinely performed to aid diagnosis and management.

Differences in implanting techniques and mechanisms of closure in LAAC devices may affect DRT. For patients contraindicated to OAC, alternative post-LAAC antithrombotic regimens with varying duration of therapy are currently employed in real-world clinical practice.

In an ongoing effort to further elucidate the role of antiplatelet therapy post-LAAC, large randomized controlled trials are currently addressing the safety and efficacy of LAAC in different cohorts of patients contraindicated to OAC.

There may be significant interindividual variability, which adds uncertainty to the duration of antithrombotic therapy during DRT before complete endothelialization. Additional clinical trials are needed to validate the claims that novel devices with less thrombogenic fabric may reduce the risk for DRT.

Disclosure: Multiple authors declare affiliations within the pharmaceutical industry. Please refer to reference for a complete list of authors’ disclosures.

Reference

Saw J, Nielsen-Kudsk JE, Bergmann M, et al. Antithrombotic therapy and device-related thrombosis following endovascular left atrial appendage closure. J Am Coll Cardiol Interv. 2019.