By Michael Crawford, MD, Editor
SYNOPSIS: A recent analysis of prosthesis patients found that von Willebrand factor abnormalities were much more prevalent in dysfunctional prostheses, and were linked to both angiodysplasia and gastrointestinal bleeding.
SOURCES: Blackshear JL, McRee CW, Safford RE, et al. von Willebrand factor abnormalities and Heyde’s syndrome in dysfunctional heart valve prostheses. JAMA Cardiol2016;1:198-204.
The link between severe aortic stenosis and angiodysplasia-induced gastrointestinal (GI) bleeding is often attributed to intravascular, shear-induced changes in von Willebrand factor (VWF). Prompted by periodic reports of comparable VWF and GI bleeding in cases of dysfunctional heart valves, Blackshear et al studied 136 patients with a variety of prosthetic and repaired heart valves to test for the role of VWF. Among the patients prospectively studied, 26 presented with normally functioning aortic prosthetic valves, 24 with dysfunctional aortic prostheses, 36 with normally functioning mitral valve prostheses or repairs, 19 with dysfunctional mitral prostheses or repairs and, finally, 31 patients with native isolated regurgitation.
Dysfunctional prostheses were determined to be those with at-least-moderate stenosis or regurgitation. Multiple tests of VWF and platelet function were conducted, with measures of both taken. Seventy-seven percent of patients with moderate-to-severe native isolated AR demonstrated abnormal VWF multimers and likely platelet dysfunction. Patients with dysfunctional aortic prostheses were also more likely to have abnormal VWF multimers than those patients with normally functioning aortic valves. Likewise, a similar difference was observed between dysfunctional and normally functioning mitral valves, as patients with dysfunctional valves displayed a much higher propensity for abnormal VWF multimers. Two of the 21 (9.5%) patients with at-least-moderate native AR experienced some form of GI bleeding, while 6 of the 24 (25%) patients with dysfunctional aortic prostheses and five of the 19 (26%) with dysfunctional mitral prostheses demonstrated GI bleeding on at least one occasion. Of the six patients with both dysfunctional aortic prosthesis and GI bleeding, five also developed angiodysplasia. Each of the three patients with a dysfunctional mitral prosthesis that underwent endoscopy testing also displayed angiodysplasia. After analysis of evidence the authors concluded that in patients with dysfunctional mitral and aortic prosthesis, displayed abnormalities in VWF are linked with angiodysplasia and GI bleeding. They also suggest that VMF multimer measurements can allow for a deeper diagnostic understanding of particular patients with valve prosthesis dysfunction.