Endothelial dysfunction in microvascular angina

Abstract

A large proportion of patients with chest discomfort, thought to be angina pectoris, have normal or non-obstructive epicardial coronary arteries at angiography. However, absence of angiographic evidence of stenosis is not a sufficient criterion to fully determine the health status of the coronary vasculature as related to exclusion of ischemic heart disease (IHD). Endothelial and vascular smooth muscle dysfunction, at both the microvascular and macrovascular level, may negatively influence myocyte oxygenation and cannot be directly visualized by coronary angiography. Alternative techniques that measure coronary blood flow changes in response to stressors or resistance changes are required to more fully evaluate coronary microvascular function. Of the pathophysiological mechanisms proposed to explain functional impairment of the microvasculature as well as IHD, endothelial dysfunction is one central etiologic substrate. While dysfunctional endothelium clearly impacts coronary vasomotor properties and blood flow responses, endothelium-independent vascular smooth muscle dysfunction also has a role in the development of IHD and related symptoms like angina and is a predictor of adverse outcomes.