The effect of recombinant versus plasma-derived von Willebrand factor on prolonged PFA closure times in ECMO patients with acquired von Willebrand syndrome - an observational study.

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is applied in patients with respiratory or cardiopulmonary failure, but bleeding is a frequent complication contributing to the high mortality rates in this patient collective. A major factor predisposing patients to bleeding events is an acquired von Willebrand syndrome (aVWS). So far, specific treatment options for this phenomenon are lacking. In hereditary von Willebrand disease (VWD), treatment with recombinant or plasma-derived von Willebrand factor (rVWF or pVWF) is common practice. Closure time measured by the Platelet Function Analyser-200 (PFA-200) is an established assay to detect defects in primary hemostasis and the method is useful to monitor the effect of hemostatic therapy. The aim of this study was to assess the effect of recombinant (rVWF) vs. plasma-derived von Willebrand factor (pVWF) on closure times measured by PFA in blood obtained from ECMO patients with aVWS.

METHODS

Blood was sampled from thirteen patients receiving extracorporeal membrane oxygenation and three patients with hereditary VWD. Diagnosis of aVWS was made by conventional coagulation parameters and by multimeric structure analysis. PFA analysis of blood spiked with rVWF or pVWF was performed.

RESULTS

Thirteen patients receiving ECMO were recruited. Ten patients survived and three patients suffered major bleeding complications. PFA closure times in ECMO patients with aVWS spiked with rVWF were significantly shorter at all concentrations than with pVWF (e.g., rVWF vs. pVWF: 1 U/ml: 150.4 ± 21.7 s vs. 263.8 ± 11.7 s; 4 U/ml: 97.8 ± 9.8 s vs. 195.8 ± 15.4 s, p<0.001). PFA closure times were also significantly shorter in three patients with hereditary VWD treated with rVWF compared to pVWF (e.g., 1 U/ml rVWF vs. pVWF: 73.7±1.33 s vs. 231.3±43.4 s, p<0.01) CONCLUSION: In summary, this study shows that rVWF compared to pVWF more effectively reduced PFA closures times in blood samples of ECMO patients with aVWS. Higher doses of VWF are needed to normalize PFA closure time in blood samples of patients with ECMO-induced aVWS compared to hereditary VWD. These data support the use of PFA-200 to monitor hemostatic effects in a future clinical trial involving ECMO patients with aVWS.