Definition and epidemiology of coronary microvascular disease

Abstract

Ischemic heart disease remains one of the leading causes of death and disability worldwide. However, most patients referred for a noninvasive computed tomography coronary angiogram (CTA) or invasive coronary angiogram for the investigation of angina do not have obstructive coronary artery disease (CAD). Approximately two in five referred patients have coronary microvascular disease (CMD) as a primary diagnosis and, in addition, CMD also associates with CAD and myocardial disease (dual pathology). CMD underpins excess morbidity, impaired quality of life, significant health resource utilization, and adverse cardiovascular events. However, CMD often passes undiagnosed and the onward management of these patients is uncertain and heterogeneous. International standardized diagnostic criteria allow for the accurate diagnosis of CMD, ensuring an often overlooked patient population can be diagnosed and stratified for targeted medical therapy. Key to this is assessing coronary microvascular function-including coronary flow reserve, coronary microvascular resistance, and coronary microvascular spasm. This can be done by invasive methods (intracoronary temperature-pressure wire, intracoronary Doppler flow-pressure wire, intracoronary provocation testing) and non-invasive methods [positron emission tomography (PET), cardiac magnetic resonance imaging (CMR), transthoracic Doppler echocardiography (TTDE), cardiac computed tomography (CT)]. Coronary CTA is insensitive for CMD. Functional coronary angiography represents the combination of CAD imaging and invasive diagnostic procedures.

Keywords: Ischemic heart disease; imaging; ischemia; microvascular angina.

Figure 1

Algorithm for the investigation of patients with suspected CMD

Figure 2

Multi-modality investigations for a 66 year old woman referred to the cardiology clinic with chest pain. A Exercise Treadmill Test was inconclusive with minor upsloping ST depression without symptoms. B Invasive coronary angiogram showed smooth unobstructed coronary arteries. C Stress/rest perfusion CMR at 1.5 T coupled with inline pixel mapping of myocardial blood flow revealed normal myocardial perfusion, with normal stress MBF (Global stress MBF = 3.40 mL·min⁻¹·g⁻¹) and normal MPR (Global MPR = 3.47). The final diagnosis was non-cardiac chest pain (Acknowledgement Dr. P. Kellman and Dr. H Xue, National Institutes of Health)

Figure 3

Multi-modality investigations in a 70 year old woman with recurrent hospitalizations with chest pain and consistently associated with high-sensitivity troponin I concentrations within the normal sex-specific range (< 16 ng·L⁻¹). A The exercise treadmill test was strongly positive for ischemia with widespread horizontal ST depression. B The invasive coronary angiogram disclosed minor atherosclerotic plaque only, with no obstructive CAD. C Stress/rest perfusion CMR imaging coupled with inline pixel mapping of myocardial blood flow revealed a circumferential subendocardial perfusion defect, low stress MBF (Global stress MBF = 1.80 mL·min⁻¹·g⁻¹), and low MPR (Global MPR = 1.67). These findings are diagnostic of CMD. The final diagnosis was microvascular angina (Acknowledgement Dr. P. Kellman and Dr. H Xue, National Institutes of Health)