Postoperative
myocardial infarction (PMI) is one of the most serious complications of cardiac surgeries. No preoperative
biomarker is currently available for predicting PMI after cardiac surgeries. In the present study, we used a
phage display peptide library to screen potential preoperative
peptide biomarkers for predicting PMI after
coronary artery bypass grafting (CABG) surgery. Twenty patients who developed PMI after CABG and 20 age-, sex-, and body mass index-matched patients without PMI after CABG were enrolled as a discovery cohort. Another 50 patients who developed PMI after CABG and 50 randomly selected patients without PMI after CABG were enrolled as a validation cohort to validate the potential
peptide biomarkers identified in the discovery cohort. Fifty randomly selected healthy volunteers were also enrolled in the validation phase as a healthy control group. In the discovery/screening phase, 17 out of 20 randomly selected phage clones exhibited specific reaction with purified sera
IgG from the PMI group, among which 11 came from the same phage clone with inserted
peptide sequence GVIMVIAVSCVF (named PMI-1). In the validation phase, phage ELISA showed that serum
IgG from 90% of patients in the PMI group had a positive reaction with PMI-1; in contrast, only 14% and 6% of patients in the non-PMI group and the healthy control group had a positive reaction with PMI-1, respectively. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the PMI-1 phage clone to preoperatively identify patients who would develop PMI after CABG were 90.0%, 86.0%, 86.5, 89.5% and 88.0%, respectively. The absorbance value of the PMI-1 phage clone showed statistically significant correlation with the peak postoperative serum cardiac
troponin I level (r = 0.349, p = 0.012) in the PMI group. In conclusion, we for the first time identified a mimic
peptide (PMI-1) with high validity in preoperative prediction of PMI after CABG.