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 techn etium-99m sestamibi myocardial scin- tigraphy underestimates the prese nce of viable myocardium in asynergic territories. Stimulation that im proves coronary blood flow could increase tracer uptake in hibernating territories. Methods. Nineteen patients with a previous myocardial in farction and left ventricular dysfunction scheduled for revascularizat ion underwent quantitative technetium-99m sestamibi tomography under b aseline conditions and during isosorbide dinitrate infusion Global and regional function were assessed, respectively, before and after revas cularization by radionuclide angiocardiography and two dimensional ech ocardiography. Results. Seven patients (group A) showed postrevascular ization regional function recovery, and 12 (group B) showed no signifi cant changes. in group A, nitrate infusion induced a decrease in the e xtent of the global uptake defect ([mean +/- SD] -37.4 +/- 21.6% of ba seline 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 c hanges in ejection fraction (r -0.94, SEE 7.6). After revascularizatio n, 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 de fect, whereas only 4 of 34 of the fibrotic territories showed a nitrat e-induced uptake improvement. Conclusions. Short term administration o f isosorbide dinitrate immediately before injection of technetium-99m sestamibi increases tracer uptake in some chronically hypoperfused asy nergic territories. This finding correlates with the observation of po strevascularization functional recovery. Nitrate technetium-99m sestam ibi myocardial scintigraphy could be a promising method for the noninv asive detection of viable hibernating myocardium.