Pilot investigation of a novel testing strategy for bleeding in ventricular assist device recipients

PURPOSE: A universal loss of von Willebrand factor (vWF) high-molecular-weight multimers (HMWM) has been demonstrated in continuous-flow left ventricular assist device (HeartMate II) recipients. However, no reliable clinical or laboratory predictors for an increased bleeding tendency in this patient population have been identified. This study evaluated the ability of a new automated latex particle-enhanced immunoturbidimetric vWF activity assay (ALPEIVA) to predict non-surgical bleeding risk in HeartMate II recipients. METHODS: As part of a prospective multicenter trial, pre-surgical, 7-day, and 30-day post-implantation blood samples were collected from 24 patients. ALPEIVA-assessed vWF activities were compared among patients with and without non-surgical bleeding complications after HeartMate II implantation. Additional laboratory testing included factor VIII activity (FVIII:C), vWF antigen (vWFAg), vWF ristocetin cofactor activity (vWF:RCo), and vWF multimer analysis. RESULTS: All 24 patients had HMWM losses after HeartMate II implantation. Five patients (20%) developed non-surgical bleeding complications between 14 days and 6 months after HeartMate II implantation. Among various laboratory variables, only mean ALPEIVA/vWFAg ratios (referred to as the "bleeding ratio") were significantly lower in patients with clinically relevant bleeding (mean, 0.70 ± 0.06) compared with patients without bleeding (mean, 0.78 ± 0.09; p = 0.02) when measured at 30 days. CONCLUSIONS: The post-surgical bleeding ratio could potentially predict non-surgical bleeding risk and guide anti-platelet and anti-coagulation strategies in HeartMate II recipients.