Introductions• The challenge of Diagnosing Myocardial Ischemia in the Emergency Department..• Why did currently discovered biomarkers havent reached clinical practice yet?• Benefits and challenges in metabolomics..• Advantages of NMR + multivariate analysis: – Powerful, reproducible, inexpensive. – Simultaneous measurement of small concentrations – Ability to detect the physiochemical status of the metabolites
Aim of the study• developing a metabolic profile of acute MIS in peripheral blood serum. – Swine and patients, highly controlled models of MIS based on transient angioplasty balloon– induced coronary occlusion were used for this purpose, – clinical validation was carried out in patients with spontaneous acute chest pain and normal electrocardiographic results and troponin values
• The animal model: – 12h fasting juvenile pigs were sedated and anaesthesized. – transient angioplasty balloon–induced MIS in the proximal left anterior descending coronary artery was induced – MIS confirmed by ECG.. – Balloon deflated after 5 minutes – Blood samples withdrawn after 10 and 120 minutes – Animal recovered – Comparison was done using blood from own animal before the procedure as control
• Controlled MIS models in Patients: – Non ACS pts scheduled for PCI for stable angina – Balloon inflation time was 1 minutes then stent was implanted – No complications were recorded – Blood samples withdrawn after 10 and 120 minutes – Controls were patients with normal coronary arteries diagnosed by angiography – Blood samples of controls were also withdrawn after 10 and 120 minutes• Study group with spontaneous chest pain – To determine accuracy of the method – Pts presented with ST elevation or high tropnin I were excluded
• NMR spectroscopy: – 20ul of plasma + 2ul of D2O and measured at 37°C – Signal of selected metabolites were quantified PCA/PLS-DA were applied to the NMR spectral data base leave one out cross validation (LOOCV) of results was then applied• Statistical analysis: – mean±SD in tables and as box plots in figures – Comparison models: • Before vs. after ischemia (in humans and swine) • Patients vs. controls (at 10 minutes samples) • No MIS vs. MIS (in pts with chest pain at the ER) – Continuous data t-Test, Mann-Whitney 2-tailed test – Categorical data chi-square, Fisher exact test – PLS-DA accuracy test ROC analysis
• under highly controlled conditions of coronary flow restriction, immediate and striking changes in the metabolic profile of peripheral blood serum can be detected using NMR spectroscopy.• metabolomics in a swine model provided very reproducible, consistent, and robust markers of severe MIS. Afterward, this information was validated in human subjects.• Advantages of using animal models: – Although animal model showed low sensitivity biomarkers, rather potential high specificity in a severe ischemia scenario was detected – Reduction in human subjects needed
• Glucose/FA metabolism and acute ischemia..• Other changes found: – Lactate release – Interruption in TCA cycle activity – down-regulation in enzymes involved in FA oxidation and Glucose metabolism – Liver mediated TCA activity through vassopressin – Increased oxidation of FA though release of catecholamines – Increase circulation of TGs during MIS as suggested by this study.• The delayed increase in creatine, could be explained by an increased ischemia-related transport of ATP between cytoplasm and the mitochondria of cardiomyocytes.
Clinical Validation• This metabolic biosignature showed high accuracy in discriminating those patients with and without MIS.• In most cases, the final diagnosis was not achieved until 12 hours of thorough evaluation at the cardiology department!
Study limitaions• Although this method showed potential in reaching clinical practice in the future the author recommends wider studies with larger groups of patients with chest pain.
Conclusion• Metabolomics, based on the model presented here, represents a robust, minimally invasive and cost effective bioprofile for the detection of acute MIS with potential clinical application.• This is the first study to apply metabolomics in the field of diagnostic medicine for CVD which shows potential in future clinical practice
My Personal Thoughts• Using animal models to induce controlled pathological environments can be useful in detecting more specific biomarkers of CVD• Using metabolomics combined with statistical cross validation between patients and control is helpful in detecting more CVD specific metabolites.