Noninvasive assessment of myocardial viability by positron emission tomography with C-11 acetate in patients with old myocardial infarction - Usefulness of low-dose dobutamine infusion

Background When patients with severely depressed left ventricular function are treated, it is crucial to know in advance how much functional recovery is expected from coronary revascularization. Methods and Results We compared the results of C-11 acetate positron emission tomography (PET) with dobutamine infusion with changes in regional wall motion evaluated by left ventriculography in 28 patients with old Q-wave anterior myocardial infarctions. Dysfunctional but viable myocardium (group A, n=13) was separated from nonviable myocardium (group B, n=15) by echocardiographic assessments of regional wall motion before and after successful coronary revascularization. C-11 acetate PET was performed to characterize normalized myocardial blood flow and oxidative metabolism (the clearance rate constant, k mono). While the baseline k monos of the infarct areas of the two groups were different with overlap, the responses to dobutamine infusion were directionally different. In addition, relative perfusion by C-11 acetate PET could predict recovery of left ventricular function as well as or better than dobutamine C-11 acetate kinetics. The extent of the increase in k monos of the infarct area with dobutamine infusion correlated well (P<.01) with the degree of the increase in the percentage of systolic segment shortening in the infarct area (left ventriculography) after coronary revascularization. Conclusions C-11 acetate PET with dobutamine infusion can predict not only the reversibility of dysfunctioning myocardium after coronary revascularization but also the extent of improvement of regional wall motion in patients with old Q-wave infarction.