Microvascular Integrity in Myocardial Injury

Infarct size and extent of transmural involvement are major determinants of left ventricular (LV) remodeling after myocardial infarction (MI), and restoration of the patency of the coronary artery alone remains the most important intervention to limit the extent of myocardial injury. Noninvasive imaging modalities, such as contrast echocardiography and cardiac magnetic resonance imaging, have shown that the integrity of microvasculature early on determines the viability of the myocardium in the area at risk. On the other hand, the extent of microvascular damage, persistent microvascular occlusion (PMO), and myocardial hemorrhage resulting from ischemia and reperfusion have been shown to adversely influence LV remodeling after MI regardless of the size of the infarct. It has also been observed that the deposition of iron in myocardium after infarction is associated with adverse LV remodeling and electrical abnormalities. The mechanisms by which PMO and interstitial hemorrhage lead to adverse LV remodeling and cardiovascular outcomes are not well understood.