Cardioreparation in hypertensive heart disease

Abstract

The normal myocardium is composed of a variety of cells. Cardiac myocytes, tethered within an extracellular matrix of fibrillar collagen, represent one third of all cells; noncardiomyocytes account for the remaining two thirds. Ventricular hypertrophy involves myocyte growth. Hypertensive heart disease (HHD) includes myocyte and nonmyocyte growth that leads to an adverse structural remodeling of the intramural coronary vasculature and matrix. In HHD, it is not the quantity of myocardium but rather its quality that accounts for increased risk of adverse cardiovascular events. Structural homogeneity of cardiac tissue is governed by a balanced equilibrium existing between stimulator and inhibitor signals that regulate cell growth, apoptosis, phenotype, and matrix turnover. Stimulators (eg, angiotensin II, aldosterone, and endothelins) are normally counterbalanced by inhibitors (eg, bradykinin, NO, and prostaglandins) in a paradigm of reciprocal regulation. To reduce the risk of heart failure and sudden cardiac death that accompanies HHD, its adverse structural remodeling must be targeted for pharmacologic intervention. Cardioprotective agents counteract the imbalance between stimulators and inhibitors. They include ACE and endopeptidase inhibitors and respective receptor antagonists. Cardioreparative agents reverse the growth-promoting state and regress existing abnormalities in coronary vascular and matrix structure. ACE inhibition has achieved this outcome with favorable impact on vasomotor reactivity and tissue stiffness. Today's management of hypertension should not simply focus on a reduction in blood pressure, it must also target the adverse structural remodeling that begets HHD.