Assessment of nicorandil therapy in ischemic myocardial injury by using contrast-enhanced and functional MR imaging

PURPOSE: To determine the potential of mesoporphyrin- and gaclopentetate cl imeglumine-enhanced and functional magnetic resonance (MR) imaging in the a ssessment of the acute effect of nicorandil on ischemic injury of the myoca rdium. MATERIALS AND METHODS: Spin-echo MR imaging was used to monitor changes in myocardial contrast and function in reperfused myocardial injury. Inversion -recovery echo-planar MR imaging was used to depict the injured region. Myo cardial injury in rats was produced by using 30 minutes of coronary occlusi on followed by 24 hours reperfusion. Nicorandil (n = 9) was infused during occlusion and early reperfusion. Control animals (n = 11) received no thera py. At 24 hours, after administration of mesoporphyrin and gaclopentetate d imeglumine and histochemical staining, the function and size of the injured region of the left ventricle (LV) were determined. A t test was used to co mpare data between groups of animals, whereas regression and Bland-Altman a nalyses were used to determine correlation and agreement between MR imaging and histomorphometry, respectively. RESULTS: Treated animals showed reduced infarction size as compared with th e control group from 25.6% +/- 7.9 (SD) to 7.9% +/- 6.8 of LV myocardial ar ea (P < .001), as defined with mesoporphyrin-enhanced MR imaging; while the size of the rim increased from 10.8% +/- 10.0 to 16.1% +/- 14.4 (P < .05). The diastolic-midventricular cavity area was smaller in treated animals (1 5.2 mm(2) +/- 4.3) compared with the control group (28.5 mm(2) +/- 7.9; P < .001). At functional MR imaging, nicorandil improved systolic reduction in LV cavity area (57.5% +/- 17.3) compared with the control group (38.0% +/- 16.0; P < .05) and preserved regional LV wall thickening at the site of in jury (12.2% +/- 11.1 in treated group vs 0.3% +/- 8.6 in the control group; P < .05). CONCLUSION: Contrast material-enhanced MR imaging has the potential to demo nstrate reduction in size of ischemically injured myocardium, whereas funct ional MR imaging demonstrated the recovery of LV function 24 hours after ni corandil therapy.