Myocardial ischaemic syndromes: a new nomenclature to harmonize evolving international clinical practice guidelines.

Since the 1960s, cardiologists have adopted several binary classification systems for acute myocardial infarction (MI) that facilitated improved patient management. Conversely, for chronic stable manifestations of myocardial ischaemia, various classifications have emerged over time, often with conflicting terminology-e.g. 'stable coronary artery disease' (CAD), 'stable ischaemic heart disease', and 'chronic coronary syndromes' (CCS). While the 2019 European guidelines introduced CCS to impart symmetry with 'acute coronary syndromes' (ACS), the 2023 American guidelines endorsed the alternative term 'chronic coronary disease'. An unintended consequence of these competing classifications is perpetuation of the restrictive terms 'coronary' and 'disease', often connoting only a singular obstructive CAD mechanism. It is now important to advance a more broadly inclusive terminology for both obstructive and non-obstructive causes of angina and myocardial ischaemia that fosters conceptual clarity and unifies dyssynchronous nomenclatures across guidelines. We, therefore, propose a new binary classification of 'acute myocardial ischaemic syndromes' and 'non-acute myocardial ischaemic syndromes', which comprises both obstructive epicardial and non-obstructive pathogenetic mechanisms, including microvascular dysfunction, vasospastic disorders, and non-coronary causes. We herein retain accepted categories of ACS, ST-segment elevation MI, and non-ST-segment elevation MI, as important subsets for which revascularization is of proven clinical benefit, as well as new terms like ischaemia and MI with non-obstructive coronary arteries. Overall, such a more encompassing nomenclature better aligns, unifies, and harmonizes different pathophysiologic causes of myocardial ischaemia and should result in more refined diagnostic and therapeutic approaches targeted to the multiple pathobiological precipitants of angina pectoris, ischaemia and infarction.