| Abstract: | The annual incidence of myocardial infarction (MI) before 40 years of age is 10 times less frequent than that in patients of all ages, and 10 times less frequent in women than men. The severity and extensiveness of lesions demonstrated by coronary arteriography are significantly less in a young patient with an infarction than an elderly patient. Significant isolated coronary artery stenosis is encountered 10 times more frequently before age 35 than after age 50; 15 percent of young patients have no significant stenosis and 8 to 14 percent have entirely normal coronary artery circulation, depending on the study. There appears, then, to be two pathogenetically distinct varieties of MI in the young patient: approximately one-half of cases exhibit multiple sclerosis seen with typical coronary artery atherosclerotic disease; the remainder, which are almost specific for young patients, represent a single obstruction due most often to the rapid development of a thrombosis on an otherwise normal vascular tree. Coronary artery spasm resulting in complete arterial occlusion is certainly involved, nevertheless its frequency must be further defined. |
