Clinical, biochemical, and rheologic factors affecting the outcome of infrainguinal bypass grafting

Purpose: The purpose of this study was to determine the effects of patient characteristics, blood rheology, and plasma biochemistry on the outcome of infrainguinal bypass grafting. Methods: Blood rheology, plasma fibrinogen, cross-linked fibrin degradation products, von Willebrand factor (vWf) and other endothelial products, and clinical variables including smoking markers were determined before surgery in patients with 184 consecutive infrainguinal bypass grafts (90 vein, 94 synthetic grafts). Results: Fifty (27%) graft occlusions and 17 (9%) deaths occurred within 1 year of surgery. On univariate analysis a poor outcome was associated with elevated preoperative plasma fibrinogen, fibrin degradation products, vWf, and platelet levels, reduced hemoglobin and systolic ankle pressure, a below-knee anastomosis, a decrease in patent calf vessels, and the presence of tissue necrosis (all p < 0.001). On multivariate analysis increased preoperative vWf levels were predictive of poor postoperative outcome (relative hazard for upper quartile versus lower quartile = 1.82), as were a low systolic ankle pressure (relative hazard = 2.51), presence of tissue necrosis (relative hazard = 2.73), and female sex (relative hazard = 1.9). None of the other variables studied was related to outcome. With a preoperative risk score derived from the results, graft patency rates within 3 months of surgery fell to less than 25% with risk scores in the upper quartile. Conclusions: Preoperative measurement of plasma vWf may enable more accurate prediction of the outcome of infrainguinal revascularization and when combined with other variables could assist in patient selection for these procedures. The association of vWf with graft occlusion supports a role for endothelial disturbance in graft occlusion.