ENHANCED DETECTION OF REVERSIBLE MYOCARDIAL HYPOPERFUSION BY TECHNETIUM 99M TETROFOSMIN IMAGING AND FIRST-PASS RADIONUCLIDE ANGIOGRAPHY AFTER NITROGLYCERIN ADMINISTRATION

Background. Reversal of ischemia after myocardial infarction by revasc ularization is worthwhile only if viability exists in a sufficiently l arge portion of the left ventricle. Methods and Results. To determine myocardial hypoperfusion reversibility and its influence on segmental and global function, we studied 50 patients after myocardial infarctio n, Three technetium 99m-tetrofosmin scintigraphies were performed: 1 a t rest, 1 after 0.6 mg sublingual nitroglycerin (NTG), and 1 after inj ection at peak stress, First-pass multigated radionuclide angiography was obtained at rest and after NTG, Each patient also underwent a stre ss,redistribution-reinjection thallium-201 scintigraphy, During stress Tc-99m-tetrofosmin, 104 segments had normal uptake, 51 showed moderat ely reduced uptake, and 186 had severely reduced uptake. Of these 186 segments, 33 (18%) improved at rest, and 41 (22%) improved only after NTG, Fifty-nine (79%) of these segments with improved uptake were also found to have reversible defects on Tl-201 imaging. In the 26 patient s with ventricular dysfunction, a 73% agreement was found between the functional and Tc-99m-tetrofosmin uptake post-NTG improvement, whereas a 69% agreement was found with thallium reinjection, No significant d ifferences were seen between 99mTc-tetrofosmin and Tl-201 imaging. Con clusion. Nitroglycerin administration during 99mTc-tetrofosmin scintig raphy improves the detection of myocardium with reversible hypoperfusi on in patients with a previous myocardial infarction.