A case of sudden death following exercise testing in a 33-year-old man is reported. The forensic autopsy showed atherosclerotic stenosis of the left coronary artery, as well as some changes in the cardiac conduction system, including anomalies of the atrioventricular node and moderate fibrosis and fatty infiltration of the branching bundle. This case demonstrates that cardiac arrest during vigorous exercise may be multifactorial and that abnormalities of the cardiac conduction system may have played some role in the fatal issue.