Platelet hyperreactivity in response to on- and off-pump coronary artery bypass grafting.

Hypercoagulability has been reported after off-pump coronary artery bypass grafting (OPCAB) compared with patients undergoing standard coronary artery bypass grafting (CABG) with cardiopulmonary bypass. The aim of this study was to evaluate the changes in platelet reactivity in response to cardiac surgery, both OPCAB and CABG. Platelet reactivity was monitored pre- and postoperatively (days 1 and 4) in elective OPCAB (n = 29) and CABG (n = 24) patients using the maximal amplitude (MA) parameter obtained with thrombelastography. Platelet reactivity was also examined at 1 month in 30 of the 53 patients. Twenty-three percent of the patients (12/53) had a preoperative MA value above normal reference value (MA > 69 mm). By postoperative day 4, 88% of the patients presented with an MA > 69 mm, and significant increases in MA were shown in both groups (p < .0001). Of the 30 patients examined at 1 month after surgery, 75% of the patients with high preoperative MA (6/8) remained at this level. In contrast, only 4.5% of patients with normal preoperative MA (1/22) presented with high MA at day 30. MA has previously been shown to correlate with the incidence of thrombotic and ischemic complications and this study identified 23% of patients needing coronary bypass surgery to be at high risk for recurrent ischemic events at 1 month after surgery, based on the MA. These results suggest that a more aggressive antithrombotic treatment might be warranted for patients undergoing coronary artery bypass grafting, both OPCAB and CABG, presenting with a high MA pre- and postsurgery.