The Effect of Angiotensin-Converting Enzyme Inhibitor on Hemodynamic Instability in Patients Undergoing Cardiopulmonary Bypass: Results of a Dose-Comparison Study

Background: Recently, hemodynamic instability including hypotension and its effect on the clinical outcome in patients treated with angiotensin-converting enzyme inhibitors (ACEIs) during coronary artery by ass graft (CABG) has been described. However, no analysis has examined the dose of ACEIs and its risk of hypotension. In this study, we tested the hypothesis that a higher dose of ACEIs could lead to increased episodes of hypotension. Methods: A total of 300 patients scheduled for CABG were studied prospectively. They were divided into 3 groups according to their preoperative use of different doses of ACEIs. The demographic and medical characteristics were compared between these 3 groups. During CABG and throughout the intensive care unit (ICU), vasoconstrictors were infused in patients Undergoing hypotension (mean arterial pressure [MAP] < 65 mm Fig or >30% below baseline). The predictive factors responsible for hypotension were investigated separately using univariate and. multivariate logistic regression models. Results: The 3 groups were similar with regard to the patients' demographic and medical characteristics. The patients treated with ACEIs were more likely to develop hypotension (73% of high dose and 47% of low dose) in the operating room than those Without ACEIs (30%). However, in the ICU, there was no significant association between hemodynamic changes and ACEIs-treated patients. Other independent risk factors identified for hypotension were ejection fraction, history of myocardial infarction, coronary grafting Count, and Pump time during surgery and/or ICU admission. Conclusions: Hemodynamic changes during CABC were observed to be directly proportional to the dosage of ACEIs prescribed preoperatively.