The effects of ACE inhibition on progression of atherosclerosis.

Angiotensin-converting enzyme inhibitors have been extensively studied and established in the treatment of hypertension, heart failure, and ventricular dysfunction. They have various cardiac and vascular protective effects, but the relevant mechanisms of action in these areas remain to be fully understood. Possible effects of converting-enzyme inhibition related to maintenance of normal endothelial function and inhibition of atherosclerosis should be distinguished from effects on myointimal proliferation related to vascular injury and regression of vascular hypertrophy from blood pressure reduction. Experimental animal studies have showed benefit from converting-enzyme inhibition in preventing myointimal proliferation after vascular injury in some species, but no such effect has been shown in clinical studies of restenosis following coronary angioplasty. Laboratory studies have demonstrated a protective effect of converting-enzyme inhibition on endothelial vasomotor function. Further studies have demonstrated prevention of atherosclerosis in hyperlipidemic rabbits and cholesterol-fed cynomolgus monkeys. Possible mechanisms of action apart from blood pressure lowering include inhibition of angiotensin II and other tissue growth factors and accumulation of kinins. These data, among others, provide sufficient rationale for clinical studies to determine whether converting-enzyme inhibitors can reduce atherosclerotic disease and thus widen their application as cardiac and vascular protective agents.