Reasonably specific markers for blood tests including creatine kinase muscle/brain isoform (CK-MB), cardiac troponin T (cTnT) and cardiac troponin I (cTnI) are released after the onset of significant necrosis instead of early ischemia, and they all require a level of myocardial necrosis to prompt their release from myocytes before they can be detected. This evidence concerns the gene TNNI3 and ischemia.