Changes in surface expression of platelet membrane glycoproteins and progression of heart transplant vasculopathy

Background - Transplant vasculopathy is the main limiting factor of the long-term success of heart transplantation. We sought to establish the role of platelets in the development and progression of transplant vasculopathy. Methods and Results - Platelet analysis and intracoronary ultrasound examination were performed in 78 heart transplant recipients. Quantitative intracoronary ultrasound was used to define the severity of disease at baseline (48.8±4.5 months after transplantation) and at 1-year follow-up. Platelet activation was assessed with the use of immunological surface markers of activation (ligand-induced binding site 1 [LIBS-1], P-selectin, GPIIb-IIIa) and flow cytometry. We found thai LIBS-1 immunoreactivity was significantly increased in patients with diffuse disease when compared with focal transplant disease (median [quartile], 27[14, 64] versus 18[7.9, 47], P=0.04). In a logistic regression model, we found that LIBS-1 was an independent predictor for the presence and progression of diffuse transplant vasculopathy (P=0.04). Patients with enhanced LIBS-1 levels (>75% quartile) had a 3,3-fold increased relative risk (95% CI1.8 and 18.9, P=0.002) for the presence of diffuse transplant vasculopathy. When a cutoff value of 16.5 for the level of LIBS-1 was used, patients had a4.8-fold increased relative risk (95% CI 1.9 and 12.5, P