Objectives: Routine coagulation tests and bleed-scores fail to identify patients at risk of excessive postoperative drainage following coronary artery bypass grafting (CABG). We sought to investigate whether lower von Willebrand factor (VWF) and higher ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) are associated with a high postoperative drainage after CABG.
Methods: In the prospective cohort study, VWF antigen (VWF:Ag), VWF ristocetin cofactor (VWF:RCO), VWF collagen-binding (VWF:CB), ADAMTS13 antigen (ADAMTS13:Ag) and ADAMTS13 activity were measured on the day of elective on-pump CABG in 232 consecutive patients without a prior history of haemorrhagic diathesis, including von Willebrand disease (95% discontinued aspirin preoperatively). Postoperative drainage and blood product use were recorded.
Results: A comparison of extreme drainage quartiles (n=56) showed that individuals with the highest drainage volumes have mean VWF:RCO lower by 19% (P<0.0001), median VWF:Ag lower by 19% (P<0.0001), ADAMTS13:Ag higher by 8% (P=0.0002), ADAMTS13 activity higher by 9% (P=0.01) and fibrinogen lower by 14% (P=0.03) than those with the lowest drainage. Linear regression analysis showed that preoperative VWF:RCO (b=-4.83, P=0.002) and fibrinogen (b=-61.52, P=0.04) are the only independent predictors of postoperative drainage. Multivariate logistic regression demonstrated that preoperative VWF:RCO in the lowest quartile and ADAMTS13:Ag levels in the highest quartile increased the risk of high (≥1000 ml) drainage (odds ratio [95% confidence interval]=4.88 [1.83-13.02], P=0.001 and 3.77 [1.49-9.52], P=0.005; respectively).
Conclusions: Patients undergoing elective CABG with lower preoperative VWF:RCO are at risk of having larger postoperative drainage, which suggests a novel contributor to increased perioperative bleeding in cardiac surgery.
Keywords: ADAMTS13; Chest-tube drainage; Coronary artery bypass grafting; von Willebrand factor.