Quantitatively diagnosing ischemia by non-invasively sensing mechanical vibrations from mechanical contraction of a ventricle to measure a time duration of an isovolumetric contraction and a peak endocardial acceleration (PEA) of the heart during the IVCT and calculating a myocardial contractility index (MCI) of the subject, for example MCI=PEA/IVCT. Comparing the MCI of the subject during the sensing period to a baseline MCI which is defined as the baseline MCI of the subject or a representative value of the baseline MCI of a population of subjects less a predetermined value, and then determining by a processor whether the MCI of the subject declined during the sensing period by at least a predetermined amount relative to the baseline MCI. Also allows determination of an amount of viable myocardium, existence of total occlusion of a coronary artery, myocardial infarction and whether thrombolysis has been effective so as to be discontinued.
