NITROGLYCERIN-INDUCED CHANGES IN MYOCARDIAL SESTAMIBI UPTAKE TO DETECT TISSUE VIABILITY - RADIONUCLIDE COMPARISON BEFORE AND AFTER REVASCULARIZATION

Background Nitroglycerin (NTG) is known to increase the blood supply t o the myocardium, and would thus increase the delivery of a perfusiona l tracer such as sestamibi (MIBI) to the tissue, The latter, in turn, would take up and concentrate the tracer to a greater extent than in b asal conditions only if energy-dependent mechanisms were still availab le - that is, only if the cells were still viable. Methods We evaluate d the changes that intravenous administration of NTG induced on the up take of MIBI by akinetic myocardial areas, using tomographic perfusion al imaging in 23 patients with previously ascertained anterior myocard ial infarction who were undergoing myocardial revascularization proced ures. Changes in uptake were compared with echocardiographic and perfu sional changes occurring after operation. Results The improvement of M IBI uptake after NTG correctly identified 12 of the 16 patients (75%) showing postoperative wall motion improvement; they comprised 12 of th e 14 (86%) patients with NTG-induced increase in MIBI uptake who showe d improved wall motion after operation, A close correlation (r = 0.88, P < 0.001) was found between the increase in myocardial MIBI uptake i nduced by NTG infusion and that induced by revascularization, The pres ence of collaterals to the akinetic area was associated with a signifi cantly (P < 0.01) greater increase in MIBI uptake both during NTG infu sion and after operation. Conclusions The results of this study sugges t that MIBI perfusional myocardial scintigraphy during infusion of NTG is capable of detecting viable but chronically hypoperfused myocardiu m, predicting postoperative wall motion and perfusional improvement, a nd reflecting the postoperative pattern of perfusion, The best results were achieved in patients with evidence of collateral circulation sup plying the infarcted area.