Coronary microvascular disease

Abnormalities in the function and structure of the coronary microcirculation can occur in the absence of obstructive coronary artery disease (CAD). In clinical practice, a significant proportion of patients with chest pain do not have obstructive CAD, and approximately 30–50% of these patients are believed to have coronary microvascular disease (CMD). CMD is typically defined as an inadequate increase in coronary blood flow during stress due to impaired vasodilatation of the arterioles or increased resistance in the coronary microvasculature. The diagnosis of CMD involves the assessment of microvascular function, which is determined by coronary flow reserve (CFR) and/or myocardial perfusion reserve (MPR). The causes and pathophysiology of CMD are not well understood, and thus its treatment mainly consists of the more established treatment strategies of CAD