A lethal arrhythmia, usually ventricular fibrillation, can lead to sudden cardiac death without acute myocardial ischemia being present. While coronary atherosclerosis is present in most cases of natural sudden death, at least three other factors have been implicated in the pathogenesis of the death. These include acute myocardial infarction, myocardial ischemia without infarction, and a primary arrhythmia. There is evidence that sudden cardiac death may involve acute coronary injury and unstable angina pectoris which suggests an important consideration of acute coronary alterations in such cases. 2 tables, 4 figures, and 30 references (Author abstract modified)