REST TC-99M SESTAMIBI TOMOGRAPHY IN COMBINATION WITH SHORT-TERM ADMINISTRATION OF NITRATES - FEASIBILITY AND RELIABILITY FOR PREDICTION OF POSTREVASCULARIZATION OUTCOME OF ASYNERGIC TERRITORIES

Objectives. This study investigated the role of nitrate technetium-99m sestamibi imaging in predicting the postrevascularization outcome of chronically hypoperfused asynergic territories. Background. Rest technetium-99m sestamibi myocardial scin- tigraphy underestimates the presence of viable myocardium in asynergic territories. Stimulation that improves coronary blood flow could increase tracer uptake in hibernating territories. Methods. Nineteen patients with a previous myocardial infarction and left ventricular dysfunction scheduled for revascularization underwent quantitative technetium-99m sestamibi tomography under baseline conditions and during isosorbide dinitrate infusion Global and regional function were assessed, respectively, before and after revascularization by radionuclide angiocardiography and two dimensional echocardiography. Results. Seven patients (group A) showed postrevascularization regional function recovery, and 12 (group B) showed no significant changes. in group A, nitrate infusion induced a decrease in the extent of the global uptake defect ([mean +/- SD] -37.4 +/- 21.6% of baseline value); in group B, no change or a slight increase was observed (+5.8 +/- 8.4%, p < 0.0005 vs, group A). The nitrate induced changes in the extent of uptake defect correlated with postrevascularization changes in ejection fraction (r -0.94, SEE 7.6). After revascularization, 11 asynergic vascular territories showed improvement (hibernating), and 34 remained unchanged (fibrotic). With administration of nitrates, 10 hibernating territories had a decrease in the extent of uptake defect, whereas only 4 of 34 of the fibrotic territories showed a nitrate-induced uptake improvement. Conclusions. Short term administration of isosorbide dinitrate immediately before injection of technetium-99m sestamibi increases tracer uptake in some chronically hypoperfused asynergic territories. This finding correlates with the observation of postrevascularization functional recovery. Nitrate technetium-99m sestamibi myocardial scintigraphy could be a promising method for the noninvasive detection of viable hibernating myocardium.