Beyond the coronary angiogram: Further evaluation of the coronary vasculature and endothelial function

Coronary artery disease is a progressive and diffuse process. The focus in the past decade was on the late stage of coronary atherosclerosis, with efforts being devoted to the development of thrombolytic drugs and sophisticated interventional devices. However, in spite of the success in decreasing morbidity and mortality from coronary atherosclerosis, the disease process continues. Early diagnosis and treatment of patients with nonobstructive coronary artery disease may prevent the development of unstable angina and myocardial infarction. It has become apparent that the endothelium is the primary target and/or participant in the early stages of coronary atherosclerosis. The endothelium is as an active paracrine organ capable of regulating coronary vascular tone as well as the atherosclerotic and restenosis process by releasing vasorelaxing factors with antiproliferative activity and vasoconstricting and growth factors. During the evolution of coronary atherosclerosis endothelial dysfunction occurs, which is characterized by attenuated release and activity of endothelium derived vasorelaxing factors and enhanced release of vasoconstricting factors. The goal of cardiology is to develop diagnostic methods and treatment for these patients who present to us with cardiac symptoms and nonobstructive coronary artery disease. This article will review the current knowledge of endothelial function as it applies to coronary circulation and describe a clinical approach to the patient with suspected coronary disease and a normal coronary angiogram.