The intramural coronary artery: another cause for sudden death with exercise?

SUDDEN DEATH, the ultimate complication, is generally thought of in the context of coronary artery disease. Most studies of the total experience with death that occurs suddenly and unexpectedly and is not associated with trauma conclude that about 90% are associated with pathologically significant coronary atherosclerosis.1 Sudden death in young people, especially while engaging in strenuous physical activity, is a rare and always shocking, tragic event. The causes of sudden unexpected death in young people are more varied and appear to be increasing. In this issue of Circulation, Morales, Romanelli and Boucek report three cases of sudden death that occurred during severe exercise. Autopsy revealed evidence of previous myocardial fibrosis and necrosis, which they attributed to myocardial bridging of the left anterior descending coronary artery and, in the third case, also of the right coronary artery. So we add to the short list of known causes of sudden death in young people the myocardial muscle bridge, sometimes referred to as an intramural coronary artery. The evidence presented to support this explanation, with the exception of the first case, is based entirely on the pathologic findings at autopsy. Unequivocally, all three patients had a portion of their left anterior descending coronary artery pass intramurally and all three had evidence of myocardial necrosis and fibrosis in the areas subserved by the bridged coronary vessels consistent with both old and recent myocardial injury, probably ischemic. The first case is most interesting because the patient had had an extensive medical work-up for chest pain, atypical for angina in that it was precipitated by emotional stress but not by exercise. The major clinical evidence for myocardial ischemia was a "strongly positive" Master two-step exercise test and progressive ECG changes consistent with myocardial septal fibrosis. Cardiac catheterization 8 years before death showed normal coronary arteries and, retrospectively, a "milking" of the left anterior descending coronary artery consistent with a myocardial bridge. But the first case has other findings which soften the