Abstract
BackgroundThe role of infarct size on left ventricular (LV) remodeling in heart failure after an acute ST-segment elevation myocardial infarction (STEMI) is well recognized. Infarct size, as determined by cardiovascular magnetic resonance (CMR), decreases over time. The amount, rate, and duration of infarct healing are unknown.MethodsA total of 66 patients were prospectively enrolled after reperfusion for an acute STEMI. Patients underwent a CMR evaluation within 1 week, 4 months, and 14 months after STEMI.ResultsMean infarct sizes for the 66 patients at baseline (acute necrosis), early follow-up (early scar), and late follow-up (late scar) were 25 ± 17 g, 17 ± 12 g, and 15 ± 11 g, respectively. Patients were stratified in tertiles, based on infarct size, with the largest infarcts having the greatest absolute decrease in mass at early and late scar. The percent reduction of infarct mass was independent of initial infarct size. There was an 8 g or 32% decrease in infarct mass between acute necrosis and early scar (p < 0.01) with a 2 g or 12% additional decrease in infarct mass between early and late scar (p < 0.01).ConclusionsInfarct healing is a continuous process after reperfusion for STEMI, with greatest reduction in infarct size in the first few months. The dynamic nature of infarct healing through the first year after STEMI indicates that decisions based on infarct size, and interventions to reduce infarct size, must take into consideration the time frame of measurement.
Highlights
The role of infarct size on left ventricular (LV) remodeling in heart failure after an acute ST-segment elevation myocardial infarction (STEMI) is well recognized
It is known that identification of previous MI, as determined by late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR), has a significant impact on a patient’s mortality [5,6]
We have previously shown that initial infarct size by LGE on CMR, measured within a few days after reperfusion for ST-segment elevation MI (STEMI) is associated with cardiac event-free survival [7]
Summary
The role of infarct size on left ventricular (LV) remodeling in heart failure after an acute ST-segment elevation myocardial infarction (STEMI) is well recognized. Other investigators have demonstrated that the area of LGE decreases within the first few months of the acute event [8,9,10] This change was attributed to clearing of necrotic myocardium, inflammatory cells, residual edema, and hemorrhage and replacement by scar tissue. It is unknown over what period of time infarct healing occurs from acute necrosis to chronic scar, as well as how the initial infarct size impacts the amount of healing and the degree of LV remodeling. We hypothesized that the majority of infarct healing occurs within 3–4 months of MI but continues at a slower rate for up to a year
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