Although studies in 1992 with a sufficient number of minority patients were sparse, those available suggested that Black Americans had a higher case fatality from coronary heart disease, but lesser amounts of atherosclerotic coronary artery disease. A possible explanation for this apparent paradox was that myocardial ischemia might be more prevalent with less coronary artery atherosclerosis in Black Americans because of comorbid diseases or differences in coronary physiology. This could be secondary to excess hypertension and left ventricular hypertrophy in Black Americans but might also have been related to intrinsic or acquired differences in coronary artery autoregulation and vasoreactivity leading to depression in coronary blood flow and reserve.