Clotting-protein abnormalities tied to dysfunctional heart-valve prostheses

Last Updated: 2016-04-13

By Marilynn Larkin

NEW YORK (Reuters Health) - Aortic regurgitation, prosthetic-valve dysfunction and related gastrointestinal bleeding are associated with acquired abnormalities of the clotting protein von Willebrand Factor (VWF), according to a new study.

Researchers compared data from previously reported healthy controls and patients with aortic stenosis, mitral regurgitation and left ventricular assist devices in a multispecialty practice. They included 136 patients who underwent multiple VWF laboratory tests and echocardiography.

From 2010 to 2015, the researchers assessed 26 patients with normally functioning surgical or transcatheter aortic valve replacement; 24 patients with dysfunctional aortic valve replacement; 36 patients with normally functioning mitral valve replacement or repair; 19 patients with dysfunctional mitral valve replacement or repair; and 31 patients with native aortic regurgitation without coexisting aortic stenosis, according to their report in JAMA Cardiology, online April 6.

Lead author Dr. Joseph Blackshear of the Mayo Clinic in Jacksonville, Florida, told Reuters Health by email, "This study focused first on native aortic valve regurgitation (AR), and found that 0% of mild AR but 76.9% of moderate-to-severe AR had VWF abnormalities."

"In a second group of patients with prior aortic or mitral valve replacement or repair, normal prosthesis function was associated with VWF abnormalities in 4.8% of patients, while moderate or severe prosthesis dysfunction, usually valvular or paravalvular regurgitation, was accompanied by VWF abnormalities in 79.1% of patients. Gastrointestinal bleeding and gastrointestinal angiodysplasia were seen in a minority of patients."

Dr. Blackshear added, "VWF tests appear to function as markers of prosthesis dysfunction. Thus far, blood testing during follow-up of prosthetic valves is only recommended by the European Society (of Cardiology) Valvular Heart Disease guidelines, and the blood tests are hemolysis studies. Since most patients receive tissue prostheses - either surgical or TAVR (transcatheter aortic valve replacement) - and since tissue valves have a finite life span, with both early and late modes of failure, VWF tests could be a useful serial measure of prosthesis status."

"Finally, if bleeding occurs with prosthetic valve dysfunction, acquired von Willebrand syndrome should be suspected," Dr. Blackshear continued. "In other settings, relieving turbulence through surgery has been curative of severe bleeding. Further research is needed to determine whether non-surgical approaches, such as percutaneous plug insertion for reduction of paravalvular leak is sufficient to improve VWF function."

Dr. William B. Hillegass of the Heart South Cardiovascular Group at the University of Alabama at Birmingham, coauthor of an accompanying editorial, told Reuters Health by email, "In patients with severe heart valve disease, the high shear stress-induced VFW functional deficiency appears to be a relatively common condition and poses a significant bleeding risk. The only curative treatment is surgical or transcatheter valve replacement."

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JAMA Cardiol 2016.