High Prevalence of Platelet Function Abnormalities in Patients with Aortic Stenosis

Platelet function abnormalities and acquired von Willebrand syndrome is found in more than 20% of patients with aortic stenosis. The abnormalities tend to disappear after valve replacement, unless there is a mismatch between the patient and the prosthesis, French researchers report.

Dr. André Vincentelli of the University of Lille, France, and associates enrolled 50 consecutive patients with aortic stenosis in a prospective trial. Of the 50 enrolled, 42 patients underwent valve replacement. The investigators found skin or mucosal bleeding in 21% of these patients.

High shear stress, decreased von Willebrand factor collagen-binding activity, and/or a loss of the largest multimers appeared to cause platelet function abnormalities in 67% to 92% of the patients.

“Primary haemostatic abnormalities were completely corrected on the first day after surgery but tended to recur at 6 months,” the researchers report. Recurrence of abnormalities occurred most often in patients with mismatched prosthesis (those with an effective orifice area of less than 0.8 cm2/m2 of body surface area).

Dr. Vincentelli and colleagues believe that “the haemostatic defect is related mostly to direct proteolysis of the largest multimers of von Willebrand factor.”

N Engl J Med 2003;349:4:343-349