A system, method and apparatus for detecting a cardiac event in a subject, may include at least one electrode attached to the subject for obtaining an electrocardiogram of the subject's heart, and determination means for determining a size of an area under a QRS complex of the electrocardiogram. The at least one electrode may be attached to the subject's skin or to the subject's heart. Preferably, the determination means for determining the size of the area under the QRS complex of the electrocardiogram is either visual or quantitative. The subject may be a human being or an animal. The size of the area under the QRS complex of the electrocardiogram determined by the determination means is directly proportional to the mass of a viable myocardium in the subject's heart. The cardiac event that may be detected may be degenerative cardiomyopathy, acute myocardial infarction, arrhythmia, myocardial ischaemia, or compromised ventricular function.