PREDICTION BY POSTEXERCISE FLUORO-18 DEOXYGLUCOSE POSITRON EMISSION TOMOGRAPHY OF IMPROVEMENT IN EXERCISE CAPACITY AFTER REVASCULARIZATION

The extent of ischemic and hibernating myocardium, which may be detect ed by increased postexercise uptake of fluoro-18 deoxyglucose (FDG) us ing positron emission tomography, may determine the degree of function al benefit after revascularization. This study examined the influence of the amount of this FDG-avid myocardium on changes in left ventricul ar function and exercise parameters after revascularization. Echocardi ography and exercise testing were performed before and after intervent ion in 23 patients who had undergone positron emission tomography for the evaluation of myocardial perfusion (using rubidium-82), and postex ercise FDG imaging in the fasting state. Follow-up echocardiography (2 2 +/- 14 weeks after revascularization) was compared with preoperative FDG activity in 7 myocardial regions per patient. Systolic function i mproved after intervention in 19 of 26 malperfused, dysfunctional FDG- avid regions (73%), and did not improve in 35 of 47 dysfunctional regi ons without increased FDG uptake (74%). The influence of the amount of FDG-avid tissue on changes in functional state was examined by compar ing 9 patients with multiple (greater-than-or-equal-to 2) FDG-avid reg ions with the remainder. Those with multiple FDG-avid regions demonstr ated improvement in peak rate-pressure product (20 +/- 4 to 26 +/- 4 x 10(3), p < 0.02), and percentage of maximal heart rate achieved at pe ak (84 +/- 10% to 93 +/- 6%, p = 0.04), neither of which changed signi ficantly in the remaining patients. Exercise capacity increased from 5 .6 +/- 2.7 to 7.5 +/- 1.7 METS in the group with multiple FDG-avid reg ions; this increase of 55 +/- 18% exceeded the increase of 13 +/- 10% in the remainder (p = 0.04). Thus, imaging of postexercise FDG uptake in patients with previous myocardial infarction may predict improvemen t of regional systolic function and exercise parameters after revascul arization.