Abstract
BACKGROUND: Non-surgical bleeding (NSB) is a major complication among heart failure (HF) patients supported by continuous-flow left ventricular assist devices (CF-LVADs). Understanding the hemostatic defects contributing to NSB after CF-LVAD implantation is crucial for prevention of this adverse event. The aim of this study was to examine the link between platelet glycoprotein Ibα (GPIbα) ectodomain shedding and NSB in CF-LVAD recipients and to identify a potential biomarker of NSB. METHODS: Serial blood samples were collected from 35 HF patients supported with CF-LVADs. Platelet function was evaluated by a platelet function analysis device and thromboelastography (TEG). Platelet GPIbα shedding, von Willebrand factor (vWF) antigen and vWF collagen binding capacity were determined using enzyme-linked immunosorbent assays (ELISAs). The structural analysis of vWF was performed by gel electrophoresis. These platelet function measures with vWF parameters of the patients who had NSB between 4 and 32 days after CF-LVAD implantation (bleeder) were analyzed against those without NSB (non-bleeder). Blood samples from 7 healthy individuals were collected to obtain healthy reference values for the laboratory assays. RESULTS: Elevated GPIbα shedding was found to be a pre-existing condition in all HF patients prior to CF-LVAD implantation. Post-operative level of GPIbα shedding increased and remained elevated in the bleeder group, whereas a consistent decrease was found in the non-bleeder group. A receiver operating characteristic (ROC) analysis indicated that the level of GPIbα shedding had a predictive power of NSB in patients on CF-LVAD support. CONCLUSIONS: Platelet GPIbα ectodomain shedding which attenuates platelet reactivity is associated with NSB. Plasma GPIbα level may potentially be used to refine bleeding risk stratification in CF-LVAD patients.