Glucose metabolism in relation to perfusion in patients with ischaemic heart disease

In order to correlate myocardial perfusion and residual metabolism in patients with coronary artery disease, the regional metabolic rate of glucose (rMRGlu) was compared with regional perfusion under glucose loading state (GL) and fasting state (FA). Fluorine-18 deoxyglucose dynamic scan was obtained in ten patients after oral GL and in 16 patients under FA. rMRGlu in seven segments was calculated using Patlak graphic analysis for comparison with normalized percent uptake of nitrogen-13 ammonia at rest in each segment. When perfusion was less than 45%, no segment showed an increase in rMRGlu (> or = 0.3 mumol/min/g) under either FA (0/6 segments) or GL (0/8 segments), indicating a certain threshold of perfusion for maintenance of glucose metabolism. When perfusion exceeded 45%, rMRGlu was higher in GL (0.37 +/- 0.18 mumol/min/g) than FA (0.15 +/- 0.12 mumol/min/g, P < 0.001) but there was very wide scatter of rMRGlu values under both states. Thus, both myocardium with preserved and myocardium with reduced glucose metabolism may exist when the perfusion exceeds 45%. In conclusion, a minimum threshold of perfusion for the maintenance of glucose metabolism may exist under both FA and GL. Below the threshold, irreversible damage may occur in the myocardium. Above the threshold, quantitative analysis of glucose metabolism should play an important role in differentiating reversibly injured myocardium from necrotic myocardium.