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.1 Noninvasive imaging modalities, such as contrast echocardiography2 and cardiac magnetic resonance imaging,3 have shown that the integrity of microvasculature early on determines the viability of the myocardium in the area at risk.4 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.5 It has also been observed that the deposition of iron in myocardium after infarction is associated with adverse LV remodeling and electrical abnormalities.6 The mechanisms by which PMO and interstitial hemorrhage lead to adverse LV remodeling and cardiovascular outcomes are not well understood.See Article by Kali et al In this issue of Circulation: Cardiovascular Imaging , Kali et al7 investigated the possible relationship between PMO, the extent of crystalline iron deposition in the myocardium, and adverse LV remodeling. Their study included 33 canines, wherein the left anterior descending was occluded for 3 hours followed either by reperfusion (n=17) or permanent occlusion (n=16). Serial cardiac magnetic resonance imaging was performed in all animals on day 7 (acute phase) …