Why, When and How Should Clinicians Use Physiology in Patients with Acute Coronary Syndromes?

Current data support the use of coronary physiology in patients with acute coronary syndrome (ACS). In patients with ST-elevation MI, the extent of myocardial damage and microvascular dysfunction create a complex conundrum to assimilate when considering clinical management and risk stratification. In this setting, the index of microcirculatory resistance emerged as an accurate tool to identify patients at risk of suboptimal myocardial reperfusion after primary percutaneous coronary intervention who may benefit from novel adjunctive therapies. In the context of non-ST-elevation ACS, coronary physiology should be carefully interpreted and often integrated with intracoronary imaging, especially in cases of ambiguous culprit lesion. Conversely, the functional assessment of bystander coronary disease is favoured by the available evidence, aiming to achieve complete revascularisation. Based on everyday clinical scenarios, the authors illustrate the available evidence and provide recommendations for the functional assessment of infarct-related artery and non-culprit lesions in patients with ACS.