Coronary Microvascular Dysfunction, Microvascular Angina, and Management

Abstract

Recent analyses have found that coronary microvascular dysfunction (CMD) portends a poor prognosis in patients with and without obstructive epicardial coronary artery disease (CAD). Chest pain in the absence of epicardial CAD is a common entity. Angina caused by CMD, microvascular angina (MVA), is often indistinguishable from that caused by obstructive epicardial CAD. The recent emergence of noninvasive techniques that can identify CMD, such as stress positron-emission tomography (PET) and cardiovascular magnetic resonance (CMR) myocardial perfusion imaging, allow improved identification of MVA. Using these tools, higher risk patients with MVA can be differentiated from those at lower risk in the heterogeneous population historically labeled as cardiac syndrome X. Likewise, MVA can be diagnosed in those with obstructive epicardial CAD who have persistent angina despite successful revascularization. There is little evidence to support current treatment strategies for MVA and current literature has not clearly defined CMD or whether therapy improves prognosis.

Keywords: Coronary microvascular dysfunction; Microvascular angina; Prognosis; Therapeutics.

Figure 1

This figure illustrates the coronary flow reserve (CFR) cutoffs that have been used in studies showing a worse prognosis among patients with coronary microvascular dysfunction (CMD) with (red font) and without (black font) obstructive coronary artery disease (CAD). A proposed definition of CMD is illustrated that shows ranges of CFR that represent definite CMD, possible CMD, and the absence of CMD.