Effect of Diabetes on Myocardial Infarct and No Reflow Size in an Experimental Rat Model and Clinical Trial

Background: We determined the effect of diabetes on no reflow and myocardial infarct sizes in both an experimental rat model of diabetes and a contemporary trial of subjects with STEMI. Methods: Adult Zucker Diabetic Fatty (ZDF) and Sprague Dawley (SD) rats (n=15 each group) were subjected to left coronary artery occlusion for 30 min followed by 3 h of reperfusion. In the clinical trial, the myocardial infarct (MI) size and the zone of microvascular obstruction were assessed in 258 non-diabetic MI patient and 34 diabetic MI patients. Results: There was no difference in infarct size (median) in ZDF rats (49.9%) versus SD rats (59.6%; p=0.32); there was no difference in no-reflow size (mean ± SEM) in ZDF rats (32.5 ± 3.5%) versus SD rats (32.7 ± 4.3%; p=0.97). In the clinical study, CK-MB and Troponin I area under the curve at 72 h were comparable between the 2 groups. Infarct size by MRI on day 4 was 37.9 ± 1.8 ml in 216 non-diabetic patients and 34.8 ± 4.7 ml in 27 diabetic patients (p=0.559). The ratio of micro vascular obstruction on day 4 on the MRI was 0.179 ± 0.018 of the left ventricle in 200 non-diabetic patients and 0.220 ± 0.060 of the left ventricle in 23 diabetic patients. Conclusions: Both animal and clinical studies demonstrated no evidence for a larger infarct size, or larger area of no reflow in the diabetic compared to non-diabetic conditions.