Up to 40% of patients undergoing investigation for angina pectoris have no evidence of significant epicardial coronary disease by either elective computed tomography coronary angiography or invasive cardiac catheterization. Myocardial ischaemia can be detected in a large proportion of these patients. There is a wide spectrum of pathophysiological mechanisms that can be responsible for myocardial ischaemia in the absence of significant epicardial coronary atherosclerotic disease which can occur in different compartments of the coronary circulation.1 (Graphical abstract). However, in many cases, these are not fully appreciated or routinely pursued in clinical practice, resulting in many patients continuing to experience reduced quality of life and increased risk of adverse events.
