Annular subaortic aneurysm resulting in sudden death.

A subvalvular aneurysm in a 34-year-old black woman developed beneath the left coronary cusp of the aortic valve and extended in the epicardium between the aortic root and left atrium. She was asymptomatic until she expired suddenly from myocardial ischemia caused by compression of the circumflex coronary artery by the aneurysm. A review of the literature reveals 13 reports of subaortic and 58 submitral aneurysms but only two instances of myocardial infarction secondary to coronary artery compression by spontaneous subvalvular aneurysms in either the subaortic or submitral position.