The effect of preoperative aspirin administration on postoperative level of von Willebrand factor in off-pump coronary artery bypass surgery

The effect of preoperative administration of aspirin on endothelial function in the patients undergoing off-pump coronary artery bypass (OPCAB) surgery is still unclear. Fifty consecutive patients undergoing OPCAB between May 2006 and May 2007 were equally divided into two groups — one without preoperative aspirin (group A; the first 25 patients) and the other with preoperative aspirin (group B; the next 25 patients). We investigated the degree of postoperative endothelial dysfunction by measuring the von Willebrand factor activity, which is a possible indicator of endothelial damage. The level of von Willebrand factor was not different between groups before surgery (group A 166% ± 53% vs group B 181% ± 62%; P = 0.39). Immediately after surgery it was significantly higher than before surgery in group A (231% ± 79%; rate of increase 1.24 ± 0.58), but not in group B (183% ± 77%; rate of increase 1.03 ± 0.55) (P < 0.02). The level was still significantly higher in group A than in group B on postoperative day 1 (group A 294 ± 66 vs 254 ± 51; P = 0.03), but there was no difference between groups on postoperative day 6. Although the frequency of blood transfusion was higher in group B, there was no difference in the amount of intraoperative bleeding between the groups. Preoperative use of aspirin before OPCAB could suppress the postoperative increase in von Willebrand factor, a possible indicator of endothelial damage, only in the early postoperative phase.