DECisive Intracoronary PHysiology and Imaging in the Evaluation and Reclassification of Non-culprit Lesions in Acute Coronary Syndrome

Despite all advances in diagnostic and therapeutic methods over the past century, ischemic heart disease (IHD) remains a leading cause of mortality and morbidity worldwide. IHD develops as a result of reversible or irreversible impairment of myocardial perfusion in acute or chronic settings. This perfusion abnormality most commonly arises from compromise of epicardial coronary artery patency due to stenosis, occlusion, or vasomotor abnormalities. Structural and/or functional alterations in the microcirculation may also contribute to impaired myocardial perfusion. Conditions in which myocardial perfusion is acutely compromised are classified as acute coronary syndromes (ACS), whereas reversible ischemia developing on a chronic basis is evaluated under the umbrella of chronic coronary syndromes (CCS). In the assessment of epicardial (macrovascular) or microvascular pathologies leading to ischemia in CCS, angiography, a macroscopic lumenographic method, is often insufficient. Intracoronary pressure and flow measurements are required to determine the impact of angiographically detected epicardial lesions on coronary blood flow, perfusion pressure, and consequently myocardial perfusion. These measurements are referred to as invasive intracoronary physiology (IIP). Current guidelines recommend that decisions regarding revascularization of intermediate epicardial lesions should be based on IIP. Revascularization guided by IIP is associated with reduced mortality and morbidity, along with a lower stent burden. IIP can be performed using pressure-based, flow-based, or combined strategies. Recent multinational studies indicate that strategies integrating both flow and pressure parameters achieve better clinical outcomes with fewer interventions and reduced stent implantation compared to pressure-only approaches. Indeed, in cases where coronary flow and flow reserve are preserved, abnormalities in pressure parameters alone may not justify revascularization. Nevertheless, le