Iodine-123-BMIPP myocardial washout and cardiac work during exercise in normal and ischemic hearts

Iodine-123-BMIPP washout at rest and after exercise was investigated in relation to cardiac work in normal and ischemic myocardium. Methods: Sixteen healthy volunteers and 10 patients with ischemic heart disease were examined. After injection of 111 MBq of I-123-BMIPP, successive SPECT imaging was performed to evaluate washout ratio (WR) at rest and after mild and maximal exercise. Results: In the healthy volunteers, the mean WR was 3.3 +/- 3.5% after 1 hr of rest and increased during both mild and maximal exercise. The WR showed a better correlation with net pressure rate product (PRP) than with the peak PRP. After maximal exercise, the WR showed a distinct correlation with the net PRP in the range from 200-300 x 10(3) mmHg/min and then showed a plateau greater than 10%. In five ischemic heart disease patients with the net PRP greater than or equal to 300 x 10(3) mmHg/min, the exercise WR values were significantly elevated in normal segments relative to ischemic segments. Conclusion: BMIPP washout increased with the increase in cardiac work during exercise in normal myocardium but not in ischemic myocardium. A certain amount of exercise is necessary to evaluate fatty acid metabolism in normal and ischemic myocardium.