The Association of Hematological Markers with Occurrence of Thrombotic and Bleeding Events following Left Atrial Appendage Occlusion.

Introduction: Patients undergoing left atrial appendage occlusion (LAAO) are at increased risk for bleeding or thromboembolic events. Concurrently, biomarkers are of growing importance in risk stratification for atrial fibrillation patients. We aimed to evaluate the association of hematological markers and clinical characteristics with the occurrence of thromboembolic and bleeding events following LAAO.

Methods: Seven implanting centers retrospectively gathered data on hematological markers (i.e., platelet count [PC], mean platelet volume [MPV], and fibrinogen) prior to LAAO. Prespecified thromboembolic and major bleeding outcomes were collected and the association with pre-procedural hematological markers and clinical characteristics was evaluated using Cox regression analysis.

Results: In total, 1,315 patients were included (74 ± 9 years, 36% female, CHA2DS2-VASc 4.3 ± 1.5, HAS-BLED 3.3 ± 1.1). Over a total follow-up duration of 2,682 patient years, 77 thromboembolic events and 107 major bleeding events occurred after LAAO. Baseline PC was the only biomarker showing a signal for a relation to thromboembolic events (HR 1.18, 95% CI: 1.00-1.39) per 50*109 increment, p = 0.056). Thrombotic event rates, including device-related thrombus, increased within higher PC quartiles. Thromboembolism was associated with age (HR 1.05, 95% CI: 1.00-1.10, per year increase) and prior thromboembolism (HR 2.08, 95% CI: 1.07-4.03), but with none of the biomarkers in multivariate analysis. No association of any of the hematological markers with major bleeding was observed. Major bleeding following LAAO was associated with prior major bleeding (HR 5.27, 95% CI: 2.71-10.22), renal disease (HR 1.93, 95% CI: 1.17-3.18), and discharge on dual antiplatelet therapy (DAPT) (HR 1.71, 95% CI: 1.05-2.77).

Conclusion: Most thrombotic events occurred in the highest PC quartile, but no association of any of the hematological markers with thromboembolism or major bleeding was observed in our analysis. In multivariate analysis, older age and prior thromboembolism were associated with thromboembolism. Prior major bleeding, renal disease and discharge on DAPT were multivariate predictors of major bleeding after LAAO.