Serum amino acid profiles in acute myocardial infarction: NMR metabolomics comparison of STEMI, NSTEMI, and controls.

Altered amino acid metabolism may reflect the acute metabolic response to atherosclerotic cardiovascular disease, but its association with acute myocardial infarction (AMI) remains unclear. This study aimed to characterize serum amino acid profiles in patients with AMI and compare non-ST-segment elevation myocardial infarction (NSTEMI) with ST-segment elevation myocardial infarction (STEMI). In this retrospective cross-sectional study, serum samples from age-comparable controls without symptoms of coronary artery disease (CAD) and 60 patients with AMI, including 35 with NSTEMI and 25 with STEMI, were analyzed using nuclear magnetic resonance (NMR) spectroscopy. Metabolic differences were evaluated using principal component analysis (PCA), orthogonal projection to latent structures discriminant analysis (O-PLS-DA), univariate testing, and logistic regression. Thirty-one serum metabolites were identified, and validated O-PLS-DA models differentiated controls, NSTEMI, and STEMI. Compared with controls, patients with AMI had significantly lower serum concentrations of isoleucine, valine, alanine, leucine, glutamine, tyrosine, histidine, and phenylalanine. All these amino acids except glutamine were also significantly lower in STEMI than in NSTEMI. Reduced isoleucine, valine, alanine, leucine, tyrosine, histidine, and phenylalanine were consistently associated with both AMI and STEMI, whereas reduced glutamine was associated with AMI only. These findings demonstrate distinct serum amino acid alterations across AMI phenotypes and support their further investigation as exploratory indicators of acute metabolic shifts. Prospective longitudinal studies are required to determine their temporal, prognostic, and mechanistic relevance.