Exercise training improves insulin-stimulated myocardial glucose uptake in patients with dilated cardiomyopathy

Background. The effects of exercise training on myocardial substrate utilization have not previously been studied in patients with idiopathic dilated cardiomyopathy and mild heart failure. Methods and Results. Myocardial glucose uptake was studied in 15 clinically stable patients with dilated cardiomyopathy (New York Heart Association class I-II, ejection fraction 34% +/- 8%) with the use of 2-[fluorine 18]fluoro-2-deoxy-D-glucose ([F-18]FDG) and positron emission tomography under euglycemic hyperinsulinemia. Eight of these patients participated in a 5-month endurance and strength training program, whereas seven patients served as nontrained subjects. Left ventricular function was assessed by 2-dimensional echocardiography before and after the intervention. After the training period, insulin-stimulated myocardial fractional [F-18]FDG uptake and glucose uptake rates were significantly increased in the anterior, lateral, and septal walls (P < .01) in the trained subjects but remained unchanged in the nontrained subjects. In the trained patients, whole-body insulin-stimulated glucose uptake was enhanced and serum free fatty acid levels were suppressed during hyperinsulinemia compared with the baseline study (P < .05). No changes were observed in the nontrained group. Conclusions. These results indicate that exercise training in patients with dilated cardiomyopathy improves insulin-stimulated myocardial glucose uptake. This improvement in glucose uptake may be indicative of a switch in myocardial preference to a more energy-efficient substrate.