TEMPORAL CHANGES IN FUNCTION AND REGIONAL GLUCOSE-UPTAKE WITHIN STUNNED PORCINE MYOCARDIUM

This study compared the effects of porcine myocardial stunning on the uptake of [F-18]-fluorodeoxyglucose (FDG) at 24 hr and 7 days after re perfusion. Prior studies in animals subjected to severe myocardial isc hemia have shown a sustained increase in FDG uptake relative to perfus ion (FDG/MBF). The time course of recovery of FDG/MBF relative to func tion poststunning, however, has not been well characterized. Methods: Stunning was induced in eight swine by partially occluding the LAD art ery for 20 min. At 1 and 7 days postreperfusion, function was assessed by two-dimensional echocardiography and PET studies were obtained wit h FDG and either O-15-water or N-13-ammonia, Blood flow by microsphere s was determined at baseline, during ischemia and after stunning, Myoc ardial uptake of FDG relative to blood flow on matching images (FDG/MB F) was calculated for all ROIs and expressed as a ratio of LAD to non- LAD areas. Results: After stunning, left ventricular ejection fraction (LVEF) increased from 42% +/- 10% on Day 1 to 52% +/- 6% on Day 7 (p < 0.05), At Day 1, myocardial blood flow was 0.60 +/- 0.10 ml/min/g in LAD and 0.67 +/- 0.16 in non-LAD regions and neither differed at Day 7. The magnitude of FDG/MBF in the LAD region when normalized to the n on-LAD region was 1.29 +/- 0.16 on Day 1 and 1.09 +/- 0.08 on Day 7 (p < 0.05) and was inversely proportional to global measures of LVEF (r( 2) = 0.61; p < 0.005), Conclusion: The severity of postischemic LV dys function at 1 and 7 days after stunning correlates with the degree of enhanced regional glucose uptake as estimated by PET. Both normalize w ithin 7 days, suggesting that metabolic and functional abnormalities w ithin completely reperfused myocardium recover in parallel.