Microvascular Obstruction and Intramyocardial Hemorrhage in Reperfused Myocardial Infarctions: Pathophysiology and Clinical Insights From Imaging.

Microvascular injury immediately following reperfusion therapy in acute myocardial infarction (MI) has emerged as a driving force behind major adverse cardiovascular events in the postinfarction period. Although postmortem investigations and animal models have aided in developing early understanding of microvascular injury following reperfusion, imaging, particularly serial noninvasive imaging, has played a central role in cultivating critical knowledge of progressive damage to the myocardium from the onset of microvascular injury to months and years after in acute MI patients. This review summarizes the pathophysiological features of microvascular injury and downstream consequences, and the contributions noninvasive imaging has imparted in the development of this understanding. It also highlights the interventional trials that aim to mitigate the adverse consequences of microvascular injury based on imaging, identifies potential future directions of investigations to enable improved detection of disease, and demonstrates how imaging stands to play a major role in the development of novel therapies for improved management of acute MI patients. [Display omitted] • In patients reperfused for acute MI, microvascular injury following reperfusion therapy substantially increases the risk for MACE, with those that develop intramyocardial hemorrhage within the MI zone carrying the greatest risk for MACE in the post-MI period. • Currently available advanced imaging techniques can noninvasively detect and accurately characterize the type of microvascular injury following reperfusion therapy as those with microvascular obstruction only or microvascular obstruction and intramyocardial hemorrhage. • Therapies to mitigate reperfusion injury and improve outcomes need to take the type and extent of microvascular injury into account. [ABSTRACT FROM AUTHOR]