Anatomic substrate differences between black and white victims of sudden cardiac death: hypertension, coronary artery disease, or both?

Despite recent declines in mortality from coronary heart disease (CHD), it remains the major cause of death in the United States for blacks and whites. Although the prevalence of the ischemic syndromes in blacks and whites is similar, cardiac mortality and sudden cardiac death rate are higher in blacks. Recent attempts to explain the excess mortality in blacks have focused on barriers to health care and on sociocultural differences in perceptions of and responses to symptoms of CHD. However, the anatomic substrates of ischemia and sudden cardiac death are also different in blacks and whites. Obstructive coronary artery disease tends to be more severe in whites, while blacks have a greater prevalence of hypertensive heart disease. A body of evidence has recently emerged showing that the presence of left ventricular hypertrophy (LVH) is an important, potent predictor for subsequent cardiac death and that the mortality risk of LVH may be particularly high when underlying coronary disease is present. The greater prevalence and severity of hypertension and LVH in blacks may explain the higher cardiac mortality in blacks, even in the presence of less severe coronary disease. The reason why mortality risk is increased in the presence of LVH has not been established. Evidence suggests that it may be due to the increased predisposition to malignant arrhythmias and the increased frequency of potentially lethal silent ischemic events that occur in hypertensive individuals, particularly those with LVH.