DEMONSTRATION BY POSITRON TOMOGRAPHY AND 18-F DEOXYGLUCOSE OF REGIONAL MYOCARDIAL VIABILITY AFTER MYOCARDIAL-INFARCTION - INFLUENCE OF FIBRINOLYSIS AND REVASCULARIZATION

Ischemic but viable myocardium has been shown to extract more glucose than normal regions in conditions of predominant fatty acids utilization. To investigate the frequency and significance of this ''ischemic'' metabolic abnormality in patients (pts) after myocardial infarction (MI), the authors have studied 25 fasting pt mean age 61 +- 7 years. 17 had an anterior MI, 8 an inferior or lateral MI, 12 had single vessel disease, 9 were studied 5 to 11 days after fibrinolysis. Tomograms were recorded at 3 levels using FDG and a flow tracer (13N H4+ or 38K). The flow and FDG data were normalized to the region of maximum cation uptake and a FDG over flow ratio calculated (G/F). In normal regions distribution of tracers was homogenous and G/F=1.13 +- 0.07 (n=4). MI regions had either a concurrent flow and FDG reduction (to +- 36% of normal) with a normal G/F ratio (1.08 +- .09)(n=8) or a similar drop in flow with a higher FDG uptake and a decreased G/F ratio (2.05 +- 0.14)(n=12). 8 of the 9 pts submitted to fibrinolysis belonged to the second group. The authors conclude that high FDG uptake disproportionate to flow suggests persistence of viable tissue in themore » MI area or residual ischemia at a distance. It is more frequent after fibrinolysis and implies potential improvement with time or after complete revascularization.« less