Angiotensin-Converting Enzyme Inhibition Alters the Fibrinolytic Response to Cardiopulmonary Bypass

Background-Increased plasminogen activator inhibitor-1 (PAI-1) concentrations after coronary artery bypass grafting (CABG) are associated with increased risk of vein graft occlusion. Because angiotensin II stimulates PAI-1 expression, we tested the hypothesis that preoperative angiotensin-converting enzyme (ACE) inhibition decreases PAI-1 expression after CABG. Methods and Results-We measured the effects of cardiopulmonary bypass (CPB) on PAI-1 antigen and tissue-type plasminogen activator (tPA) antigen and activity in 31 patients taking an ACE inhibitor (ACEI) who were randomized to continue ACEI until the morning of surgery (ACEI group, n=19) or to discontinue it 48 hours before surgery (No-ACEI group, n= 12). Arterial blood samples were taken at baseline before CPB, twice during CPB, after separation from CPB, and on postoperative day 1 (POD1). CPB caused an early decrease in PAI-1 antigen, followed by an increase in PAI-1 antigen on POD1 (P<0.001 for effect of time). ACE inhibition attenuated the increase in PAI-1 antigen such that both PAI-1 antigen on POD1 (P=0.013) and the change in PAI-1 antigen from baseline to POD1 (P=0.009) were higher in the No-ACEI group (from 17.0±5.0 to 48.7±8.8 ng/mL) versus the ACEI group (from 19.9±3.4 to 33.1±6.2 ng/mL). There was no significant difference between the 2 groups in intraoperative tPA activity (P=0.259); however, the increase in tPA activity was significantly greater in the ACEI group than in the No-ACEI group (P=0.030). Conclusions-Preoperative ACEI attenuates the increase in PAI-1 after CABG, suggesting a role for ACE inhibition in reducing the risk of acute graft thrombosis.