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Updated: Aug 20, 2026
Myocardial Infarction and Functional Outcome Assessment in Pigs
Published on: April 25, 2014
Infarct involution and improved function during healing of acute myocardial infarction: the role of microvascular
C Joon Choi1, Shahriar Haji-Momenian, Joseph M Dimaria
1Department of Medicine, Cardiovascular Division, University of Virginia Health System, Charlottesville, Virginia 22908, USA.
Abstract:
Delayed contrast-enhanced cardiac magnetic resonance imaging (ceCMR) delineates infarct size. The presence of hypoenhancement consistent with microvascular obstruction (MO) signifies larger infarcts with a worse prognosis. We hypothesized that the size of the contrast defect (CD) on ceCMR in acutely infarcted myocardium may change during infarct healing and depend upon the presence of MO. Twenty-five patients underwent CMR on weeks 1 and 8 after reperfused myocardial infarction. After short-axis cine CMR was performed, gadolinium was infused and ceCMR images and matched tagged cine MR images were obtained in the three most dysfunctional short-axis slices on cine CMR. The area and transmural extent of hyperenhancement (HE) with or without MO representing total CD size were planimetered. Between week 1 and week 8, the CD area fell from 1729+/-970 mm2 at week 1 to 1270+/-706 mm2 (p<0.001), as did the transmural extent of infarction (71+/-22% to 63+/-24%, p<0.001). The decline in CD trended to be higher in patients with MO (840+/-807 mm2) than in HE (312+/-485 mm2, p<0.07). In the patient group as a whole, ejection fraction (EF) improved (56+/-9% to 60+/-10%, p=0.002) between weeks 1 and 8, but patients with MO showed no increase in EF. Segments with some HE demonstrated partial functional improvement whereas no improvement was seen in HE+MO segments. In patients 8 weeks after reperfused myocardial infarction (MI), the size of infarction by ceCMR decreases compared to week 1 post-MI, especially in those with microvascular obstruction in whom there is little improvement in regional or global function.
Insights
The size of myocardial infarction decreases over 8 weeks post-reperfusion, particularly in patients with microvascular obstruction. This reduction in contrast defect size correlates with limited functional recovery in those with microvascular obstruction.
Area of Science:
- Cardiology
- Radiology
- Medical Imaging
Background:
- Delayed contrast-enhanced cardiac magnetic resonance imaging (ceCMR) is crucial for assessing infarct size.
- Microvascular obstruction (MO) presence indicates larger infarcts and poorer prognosis.
Purpose of the Study:
- To investigate changes in contrast defect (CD) size on ceCMR during infarct healing.
- To determine if MO influences CD size changes and functional recovery.
Main Methods:
- Twenty-five patients with reperfused myocardial infarction (MI) underwent ceCMR at 1 and 8 weeks post-MI.
- Assessed area and transmural extent of hyperenhancement (HE) with or without MO.
- Correlated CD size with ejection fraction (EF) and regional function.
Main Results:
- CD size significantly decreased from week 1 to week 8 (p<0.001).
- Patients with MO showed less reduction in CD size compared to those without (p<0.07).
- Global ejection fraction improved overall, but not in patients with MO; segments with HE+MO showed no functional improvement.
Conclusions:
- Infarct size, as measured by ceCMR, reduces by 8 weeks post-MI.
- Microvascular obstruction is associated with less infarct healing and impaired functional recovery.
