Nat. Rev. Cardiol. doi:10.1038/nrcardio.2017.131 Figure 3 Aetiology of chest pain without obstructive coronary artery disease Figure 3 | Aetiology of chest pain without obstructive coronary artery disease. Various causes of angina without obstructive coronary artery disease are shown. Noncardiac pain can be caused by: gastro-oesophageal reflux, musculoskeletal alterations, pulmonary and aortic diseases, psychiatric conditions, or inappropriate perception of chest pain. Causes of nonischaemic cardiac pain are: pericarditis, pericardial diseases, and arrhythmias. As for the cardiac ischaemic group, spasm of epicardial coronary arteries owing to smooth muscle dysfunction was recognized as an adjunctive, functional mechanism of transient myocardial ischaemia and angina. Heightened sensitivity of the coronary microcirculation to vasoconstrictor stimuli associated with a limited microvascular vasodilator capacity might also be the cause of microvascular angina, together with mismatch between metabolic signalling and microvascular adaptation. Other causes include dysfunction of endothelial cells of the microvascular network, most likely owing to increased oxidative stress and inflammation. Ferrari, R. et al. (2017) A ‘diamond’ approach to personalized treatment of angina Nat. Rev. Cardiol. doi:10.1038/nrcardio.2017.131