Abstract 18212: Von Willebrand Factor-ADAMTS13 System and Clinical Outcome in Patients With Non-valvular Atrial Fibrillation

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Introduction: We previously documented a direct relationship between Von Willebrand factor (VWF) concentration/activity regulated by cleaving protease - ADAMTS13 and echocardiographic measures of left atrial blood stasis with development of left atrial appendage thrombus (LAAT) in non-valvular atrial fibrillation (NVAF). Yet, long term implications of these findings are not well explored

Hypothesis: VWF-ADAMTS13 elements are better predictors of outcomes than echocardiographic features of left atrium blood stasis

Methods: 425 NVAF patients (recruited 10/4/07 - 4/27/09) who had VWF antigen, VWF activity and ADAMTS13 activity measured at baseline, were prospectively followed forward for 3 years. Spontaneous echo contrast (SEC), left atrial appendage emptying velocity (LAAEV), left atrial appendage thrombus (LAAT) were assessed by transesophageal echocardiography (TEE). Thromboembolic (TE) outcomes comprised stroke/TIA, myocardial infarction, or thromboembolism of other location. Bleeding outcomes and all-cause mortality were also registered either by clinical follow up, questionnaire or telephone communication.

Results: Amongst 374 patients (mean age 63.4±12.7, 25% females) who had complete data, 164 (43.8%) received anticoagulation continually, 19 (5%) for >2 years, 108 (29%) for < 3 months, 31 (8.3%) have not received anticoagulation. There were 27 TE events (7.2%), 18 deaths (5.1%), 19 major bleeding (5.1%) and 24 clinically relevant non-major bleeding (6.4%). In univariate analysis, VWF antigen concentration was associated with TE events (p=0.018) and all-cause mortality (p=<0.001) but not bleeding outcomes. In multivariate model, VWF antigen remained an independent predictor of all-cause mortality (p=0.002) but not TE. SEC was associated with TE complications (p=0.016) and LAAT with TE (p=0.004) and major bleeding (p=0.010). LAAEV was associated with major bleeding (p=0.019). None of TEE measures was predictive of clinical outcomes in multivariate analysis.

Conclusions: VWF antigen concentration is an independent predictor of all-cause mortality in NVAF patients but not TE or bleeding complications. TEE determinants of blood stasis do not predict outcomes in “real life” surveillance of NVAF patients.

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