SummaryUnderstanding the metabolic features of myocardial infarction (MI) is critical to its prevention and treatment. Here, we aimed to characterize the metabolic features of early MI using a tissue metabolomics method based on gas chromatography-mass spectrometry (GC-MS). Thirty-four pairs of infarcted myocardia and their matched non-infarcted myocardia were collected from 34 rats that underwent coronary artery ligation (CAL); their metabolic profiles were compared by GC-MS-based tissue metabolomics to characterize the metabolic features of MI. On the basis of differential metabolites, their diagnostic potential for MI was analyzed, and MI-related metabolic pathways were investigated. Serum samples before and post MI were used to validate the results obtained in myocardia. The metabolic profile of the infarcted myocardia was obviously different from that of the non-infarcted myocardia, as indicated by partial least squares discriminate analysis (PLS-DA) plots. Twenty-two metabolites were identified to be different between the infarcted myocardia and non-infarcted myocardia. These metabolic alterations reflect energy deficit, acidosis, oxidative stress, ionic imbalance, and cardiac injury post MI. Glutamine, glutamate, and lactate were confirmed to jointly confer a favorable potential for diagnosing MI, which can be well validated in serum. (Int Heart J 2017; 58: 441-446) Key words: Myocardial ischemia, Metabolic feature, Glutamate, Self-control study M yocardial ischemia is a leading cause of morbidity and mortality, accounting for approximately 12 million deaths annually worldwide, and is expected to continue to be a serious problem all over the world.1) Metabolism is among the first area affected post myocardial ischemia, which can then lead to different deleterious consequences, such as arrhythmia, myocardial infarction (MI), and heart failure, 2) and the latter is an irreversible myocardial injury secondary to persistent myocardial ischemia.3) Therefore, understanding metabolic features of MI is critical to its prevention and control.Several clinical studies concerning metabolic changes in plasma of MI have been carried out. The metabolic profiles of MI in plasma or serum of MI patients are increasingly being determined. Several potential biomarkers of MI or myocardial ischemia, such as phytosphingosine, sphinganine, acetylcarnitine, adenine, and inosine have been suggested. [4][5][6][7] However, circulating biomarkers may be easily influenced by diverse tissues which may affect their specifity.Thus, we should elucidate the global metabolic changes of myocardia per se, which serve as a source of systemic metabolic alterations post MI, as they are not yet fully understood. Such an understanding not only helps to explore the pathophysiological mechanisms of MI, but can also validate the results of clinical studies. Therefore, it needs to be retrotranslated from the clinical study stage to the animal study stage. Coronary artery ligation (CAL) rat models are widely used to study related pathophysiological ...