Association between serum angiotensin-converting enzyme 2 levels and postoperative myocardial infarction following coronary artery bypass grafting

Myocardial infarction (MI) is a predominant and severe complication in patients that undergo aortocoronary bypass surgery. Angiotensin-converting enzyme 2 (ACE2) activation is reportedly a protective mechanism in MI; therefore, in the present study, the association between serum ACE2 levels and postoperative MI following coronary artery bypass grafting (CABG) was investigated. Preoperative and postoperative serum ACE2 levels in 136 subjects undergoing CABG were observed and the serum ACE2 levels, 1 h post surgery, were divided into quartile categories. Following adjustment for age, gender, body mass index, hypertension, previous MI, current smoking status, hyperlipidemia, diabetes mellitus, Gensini score, aortic clamp time, number of grafts and pre-CABG medications; the risk of developing postoperative MI following CABG was observed to be significantly higher in the lowest serum ACE2 level quartile than when compared with the highest quartile (hazard ratio, 2.94; 95% confidence interval, 1.85-4.16; P=0.009). The subjects that exhibited a serum ACE2 level <= 1.06 ng/ml showed significantly higher rates of postoperative MI, arrhythmia and reduced cardiac output in addition to increased instances of in-hospital mortality post CABG, compared with those exhibiting a serum ACE2 level >1.06 ng/ml. A significant negative correlation was observed between serum ACE2 and serum cardiac troponin I levels, however, no significant association was identified between the serum ACE2 level quartiles and the ACE2 gene polymorphisms. The present study indicated that a low serum ACE2 level, 1 h post CABG was independently associated with an increased risk of postoperative MI. Thus, the serum ACE2 level may be a potential novel prognostic factor for postoperative MI following CABG.