In intact mice, 60 minutes of coronary occlusion caused a significant reduction in LVEF (from 70% to 37%, P<0.05) and depressed wall thickening in both infarcted and remote regions at 24 hours.
Does contrast-enhanced cardiac MRI accurately assess infarct size and cardiac function in intact mice early after reperfused myocardial infarction?
Contrast-enhanced cardiac MRI can accurately assess infarct size and cardiac function in intact mice early after reperfused MI, revealing contractile dysfunction in noninfarcted regions.
p-value: p=<0.05
BACKGROUND: The objective of this study was to noninvasively determine the effects of reperfused myocardial infarction (MI) on regional and global left-ventricular (LV) function 24 hours after MI in intact mice with contrast-enhanced cardiac MRI and a single, gradient-echo pulse sequence. METHODS AND RESULTS: Twenty-three mice received baseline MRI scans followed by either 60 minutes of coronary occlusion (MI group, n=15) or thoracotomy without occlusion (sham group, n=8). Gadolinium-DTPA-enhanced magnetic resonance (MR) images were acquired 24 hours after surgery. Hearts were then excised for conventional infarct size determination via 2,3,5-triphenyl tetrazolium chloride (TTC) staining. In addition to infarct size, analysis of the MR images yielded left ventricular (LV) mass, LV end-systolic volume (LVESV), LV end-diastolic volume (LVEDV), LV ejection fraction (LVEF), cardiac output, and percent LV wall thickening (%WTh). Twenty-four hours after surgery, infarct size was 28.1+/-1.8% of LV mass by MRI and 27.5+/-1.7% by TTC (P=NS). Bland-Altman analysis revealed close agreement between the results obtained by the 2 methods. MI had little effect on LVEDV but caused a 98% increase in LVESV (from 11.3 to 22.4 microL, P<0.05), which resulted in a significant reduction in LVEF (from 70% to 37%, P<0.05). Compared with LV regional function at baseline, %WTh 24 hours after MI was significantly depressed, not only in infarcted myocardium but also in regions remote from the infarct zone. In contrast, sham-operated mice showed a small but significant increase in %WTh 24 hours after surgery (P<0.05). CONCLUSIONS: MRI can accurately assess both infarct size and cardiac function in intact mice early after large, reperfused MI, revealing the existence of contractile dysfunction in noninfarcted regions of the heart.
Yang et al. (Tue,) conducted a other in Myocardial infarction (n=23). 60 minutes of coronary occlusion vs. Thoracotomy without occlusion (sham) was evaluated on Left ventricular ejection fraction (LVEF) at 24 hours (p=<0.05). In intact mice, 60 minutes of coronary occlusion caused a significant reduction in LVEF (from 70% to 37%, P<0.05) and depressed wall thickening in both infarcted and remote regions at 24 hours.