Plasma metabolomic profiling reveals lipid biomarkers for early detection of exercise-induced myocardial ischemia.

Untargeted plasma metabolomic profiling identified 13 metabolites significantly altered in both control and ischemia groups following exercise, while 9 metabolites changed exclusively in the ischemia group.

• 43 patients were enrolled after screening 89 patients with suspected myocardial ischemia at Kyungpook National University Hospital
• Control group: n = 24 (no angiographic stenosis); case group: n = 19 (>70% stenosis in vessels with diameter ≥2.5 mm)
• Plasma samples were collected before and 10 minutes after exercise stress testing using the Bruce protocol
• Untargeted LC-QTOF/MS profiling was performed with multivariate analyses including PCA and OPLS-DA to identify differential metabolites

Several phosphatidylcholine (PC) species and 13Z-docosenamide differed significantly between the ischemia and control groups following exercise.

• PC species identified as significantly different included PC (O-18:5/2:0), PC (O-16:0/22:4), PC (O-18:4/18:2), and PC (20:4/20:4)
• 13Z-docosenamide was among the notably altered metabolites distinguishing ischemia from control patients
• Multivariate modeling revealed distinct metabolic differences between the two groups
• These lipid metabolites reflect hypoxia-mediated energy shifts and oxidative stress according to pathway analysis

Three key metabolites — 13Z-docosenamide, PC (16:0/22:5), and PC (18:1/20:4) — demonstrated excellent discriminative performance for detecting exercise-induced myocardial ischemia.

• ROC analysis yielded an area under the curve of 0.941 (95% CI: 0.865–1.000)
• Sensitivity was 92% and specificity was 93%
• These three metabolites were identified via receiver operating characteristic analysis as the key discriminators
• The authors conclude these metabolites 'demonstrated strong diagnostic potential and may serve as early biomarkers for the noninvasive detection of myocardial ischemia'

Pathway analysis indicated that exercise-induced myocardial ischemia was associated with alterations in phospholipid, sphingolipid, and fatty acid metabolism.

• The metabolic pathway alterations were interpreted as reflecting hypoxia-mediated energy shifts and oxidative stress
• Phospholipid metabolism, sphingolipid metabolism, and fatty acid metabolism were the primary pathways implicated
• These findings are consistent with ischemia-related disruptions in lipid homeostasis during exercise stress

Conventional diagnostic methods have limitations in detecting early-stage myocardial ischemia, motivating the use of metabolomics as a noninvasive approach.

• Conventional methods with stated limitations include electrocardiography, coronary angiography, and myocardial perfusion imaging
• The study used exercise stress testing based on the Bruce protocol as the provocative model for ischemia induction
• LC-QTOF/MS-based metabolomics was selected as an untargeted, noninvasive plasma profiling approach
• The authors note that 'further validation in independent cohorts might be required to confirm their clinical applicability'