Magnetic resonance imaging-defined areas of microvascular obstruction after acute myocardial infarction represent microvascular destruction and haemorrhage

Abstract

The contrast-devoid core of revascularized STEMI contains extensive erythrocyte extravasation with microvascular damage. Attenuating the reperfusion-induced haemorrhage may be a novel target in future adjunctive STEMI treatment.

Letter by Jansen and van Royen Regarding Article, “Monitoring of Monocyte Recruitment in Reperfused Myocardial Infarction With Intramyocardial Hemorrhage and Microvascular Obstruction by Combined Fluorine-19 and Proton Cardiac Magnetic Resonance Imaging”

“…4 Histologically, we found that the infarcts had a core consisting of hemorrhage and microvascular destruction that corresponded perfectly with the regions denominated as microvascular obstruction area on MRI. This leads us to believe that microvascular obstruction as currently defined by the contrast-devoid areas on late-gadolinium MRI and intramyocardial hemorrhage as determined by T2-weighted imaging in fact depict the same histological substrate.…”

Temporal Evolution of Myocardial Hemorrhage and Edema in Patients After Acute ST‐Segment Elevation Myocardial Infarction: Pathophysiological Insights and Clinical Implications

“…Myocardial hemorrhage reflects the aggregation and extravasation of erythrocytes4, 20, 45 and is a manifestation of severe microvascular injury. On CMR at day 3, 5 patients without evidence of hemorrhage on T2* imaging had hypointense cores on T2 maps and microvascular obstruction on contrast imaging.…”

“…Finally, our results confirm that infarct pathologies evolve progressively after MI and thus may be amenable to targeted preventative therapeutic interventions. Robbers et al45 proposed that myocardial hemorrhage was the final consequence of severe microvascular thrombosis and that therapeutic interventions that restored microvascular perfusion might, in turn, prevent myocardial hemorrhage. Observations in the current study (Table 2; Figure 3) and by Robbers et al45 and Payne et al20 also support the notion that red blood cells may be “trapped” in the microcirculation of the culprit coronary artery, reflecting a contributing cause and/or consequence of microvascular obstruction.…”

Pathophysiological aspects and management workflow of coronary microvascular obstruction in ST-segment elevation myocardial infarction

“…12 Again, ischemia followed by reperfusion can disrupt the endothelial barrier and damage the microvasculature, facilitating extravasation of blood cells upon reperfusion and eventually causing intra-myocardial hemorrhage (IMH). 13 Of note, patients with this more severe form of CMVO seem to have a worse outcome than patients with CMVO but without IMH. 14 A third important mechanism of CMVO is represented by distal physical and chemical substances embolization.…”

“…Of note, CMR may give additional hints to the presence of IMH. 13,14 Other imaging techniques under investigation for CMVO detection include myocardial scintigraphy or hybrid positron emission tomography-computed tomography. 35 …”