Perspective:

Angina and myocardial ischemia without obstructive coronary artery disease are common clinical findings, often assumed to have a good prognosis. Most often, such patients are neither further investigated nor offered specific treatment beyond reassurance. However, the absence of significant coronary stenoses on angiography may not necessarily imply a ‘healthy’ coronary tree. In such cases, myocardial ischemia may result from different types of functional disease involving the epicardial coronary arteries, the coronary microcirculation, or both; and an accurate assessment of these components should be systematically performed after exclusion of organic epicardial disease because a correct diagnosis may have relevant prognostic and therapeutic implications. The intracoronary acetylcholine test allows the assessment of a possible epicardial vasospasm and endothelium-dependent microvascular dysfunction at the same time. Similarly, the use of a pressure wire with the adenosine test may evaluate both the functional significance of a coronary lesion and endothelium-independent microvascular dysfunction. A functional assessment of both the epicardial coronary arteries and the coronary microcirculation is strongly recommended to identify patients at higher risk of coronary events and to guide therapeutic strategies, and should be much more widely considered.