Severe Aortic and Mitral Valve Regurgitation Are Associated with von Willebrand Factor Defect.

Severe aortic stenosis can be associated with mucosal and gastrointestinal bleeding probably related to loss of high molecular weight (HMW) multimers of VWF. Possible mechanisms of this loss are enhanced proteolysis by shear-dependant metalloprotease (ADAMTS 13) of HMW multimers of VWF or increased platelet-VWF interactions leading to clearance or degradation of HMW multimers of VWF. The aim of our study was to investigate wether this high shear-stress induced loss of HMW multimers of VWF is observed in other cardiac defects associated with high pressure blood flow such as severe aortic or mitral valve regurgitation.

Twenty four consecutive patients were operated on for aortic valve regurgitation (n=11) or mitral valve regurgitation (n=13). Before surgery recent mucosal bleeding was reported in 25% patients (n=5).VWF Closure Time of PFA 100^® (CTADP) were prolonged in 87% of patients (n=20). The ratio of ristocetin cofactor activity to antigen and the ratio of collagen-binding activity to antigen were decreased in 28%(n=5) and 45%(n=10) of patients respectively. HMW multimers of VWF were decreased in 82 % (n=18) of patients. Six months after surgery, CTADP were normal in 71% (n=17) of patients, ratios were normal in all patients evaluable for this parameter (n=14) and HMW multimers of VWF increased in all patients as compared with preoperative value (8±2,5%vs10±2,3; p=0.04) but remain under value of control plasma in 63% (n=14) of patients.

In this study we demonstrated that VWF defect can be associated with severe aortic or mitral valve regurgitation and that platelet function-analyzer closure time, abnormalities of von Willebrand factor, or both could be frequent in those valve disease and might cause mucosal bleeding.