Should angiotensin converting enzyme inhibitors/angiotensin II receptor antagonists be omitted before cardiac surgery to avoid postoperative vasodilation?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether the omission of angiotensin converting inhibitors (ACEI)/angiotensin II receptor antagonists (AIIA) before cardiac surgery leads to avoidance of postoperative vasodilation. Using the reported search 421 papers were identified. Eleven papers including three randomised controlled trials (RCTs) represented the best evidence on the subject. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results and study comments and weaknesses were tabulated for these. Whereas the three small RCTs on this topic provided conflicting evidence, the remaining seven large cohort and case-control studies confirmed that preoperative ACEI therapy resulted in postoperative low systemic vascular resistance (SVR)/vasoplegia. Only two small RCTs with conflicting conclusions specifically addressed the issue of omitting ACEI/AIIA before cardiac surgery. We conclude that preoperative administration of ACEI/AIIA in patients undergoing cardiac surgery contributes to lowering of SVR/vasoplegia postoperatively thereby making omission of ACEI/AIIA before cardiac surgery a rational strategy to avoid postoperative vasodilation. However, the current available evidence to support this strategy is weak.