Advancements in the Invasive Evaluation of Coronary Microvasculature in Acute Myocardial Infarction

Coronary microvascular dysfunction represents a critical yet historically under-recognized contributor to adverse outcomes in patients with acute myocardial infarction. As contemporary revascularization strategies continue to reduce epicardial artery-related mortality, the limitations imposed by impaired microvascular perfusion have become increasingly evident. Microvascular obstruction, ischemia-reperfusion injury, and endothelial dysfunction all contribute to suboptimal myocardial recovery, despite successful epicardial intervention. Invasive methods of assessing intravascular hemodynamics have been previously described, with identification of multiple caveats in their interpretation. Although there are multiple physiological parameters describing epicardial blood flow, coronary microvasculature evaluation has been historically limited to only a few indicators, such as coronary flow reserve and the index of microvascular resistance. Moreover, their role in the evaluation of patients remains uncertain in the case of acute coronary syndromes. This review highlights the growing armamentarium of invasive and non-invasive techniques now available to characterize the coronary microvascular function with greater precision, with a focus on their role in acute myocardial infarction.