SYSTEMIC HYPERTENSION AND CORONARY-ARTERY DISEASE - THE LINK

A direct, continuous, and independent association between blood pressu re values and incidence of coronary artery disease has been well docum ented. However, the evidence that the reduction of blood pressure alon e is nor able to completely reverse the increase in the risk of corona ry artery disease associated with essential hypertension suggests that the link between hypertension and coronary artery disease is a comple x process including other factors beside the increase in blood pressur e values. In this regard, the main determinant of coronary artery dise ase in hypertensive patients seems to be the development of left ventr icular hypertrophy (LVH). In fact, hypertensive patients who died from sudden cardiac death showed a lesser degree of coronary atheroscleros is compared with normotensives, but a higher incidence of LVH. Several mechanisms can account for the increased coronary risk with LVH, incl uding (1) an increase in left ventricular (LV) mass, which by itself r equires more oxygen for tissue perfusion; (2) impairment of coronary f low reserve; (3) perivascular fibrosis, which then impairs oxygen supp ly to the myocardium; and (4) deterioration of LV diastolic function, which hampers myocardial perfusion. Recently, a study reported an impa irment of endothelial function and abnormal control of the sympathetic tone in hypertensive patients, which may contribute to the risk of co ronary artery disease. In particular, the impaired endothelial functio n resulting in a prevalence of vasoconstrictive, thrombogenic, and pro liferative factors may account for the enhanced ischemic susceptibilit y of these patients. Furthermore, the cardiac adrenergic system plays an important role in regulating myocardial blood flow. On one hand, hy pertensive patients show an exaggerated sympathetic response to physio logic stimuli, whereas on the other hand, the p-adrenergic receptor-me diated vasodilating component of the sympathetic response is blunted i n hypertension. Finally, excess body weight, dyslipidemia, glucose int olerance, and hyperinsulinemia, which are frequently interrelated, rep resent independent predictors of both coronary artery disease and hype rtension. (C) 1998 by Excerpta Medico, Inc.