Cardiovascular Magnetic Resonance of Acute Myocardial Infarction at a Very Early Stage

Objectives: Very early changes in myocardial tissue composition during acute myocardial infarction (AMI) are difficult to assess in vivo. Cardiovascular magnetic resonance (CMR) imaging provides techniques for visualizing tissue pathology.

Background: The diagnostic role of CMR in very acute stages of myocardial infarction is uncertain. We investigated signal intensity changes beginning within 60 min after acute coronary occlusion in patients undergoing therapeutic septal artery embolization.

Methods: We investigated eight patients with hypertrophic obstructive cardiomyopathy undergoing interventional septal artery embolization by applying microparticles to reduce left ventricular outflow tract obstruction. In a clinical 1.5-tesla (T) CMR system, we visualized infarct-related myocardial signal by T(1)-weighted sequences before and 20 min after administration of contrast media (delayed enhancement) and edema-related signal by T(2)-weighted spin-echo sequences before and 58 +/- 14 min after the intervention as well as on days 1, 3, 7, 14, 28, 90, and 180 during follow-up.

Results: Infarct-related changes as defined by contrast enhancement were observed as early as 1 h after the intervention and during six months of follow-up. In contrast, infarct-related myocardial edema, as visualized by high signal intensity in T(2)-weighted spin-echo sequences, was not consistently detectable 1 h after acute arterial occlusion; this was possible in all subsequent studies until day 28.

Conclusions: Contrast-enhanced magnetic resonance imaging detected infarct-related signal changes as early as 1 h after AMI in humans, whereas the sensitivity of edema-related signal changes was not sufficient during this very early stage.