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 revascularization is worth-while only if viability exists in a sufficiently large 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 infarction. Three technetium 99m-tetrofosmin scintigraphies were performed: 1 at rest, 1 after 0.6 mg sublingual nitroglycerin (NTG), and 1 after injection at peak stress. First-pass multigated radionuclide angiography was obtained at rest and after NTG. Each patient also underwent a stress redistribution-reinjection thallium-201 scintigraphy. During stress ^99mTc-tetrofosmin, 104 segments had normal uptake, 51 showed moderately 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 ²⁰¹Tl imaging. In the 26 patients with ventricular dysfunction, a 73% agreement was found between the functional and ^99mTc-tetrofosmin uptake post-NTG improvement, whereas a 69% agreement was found with thallium reinjection. No significant differences were seen between ^99mTc-tetrofosmin and ²⁰¹Tl imaging. Conclusion  Nitroglycerin administration during ^99mTc-tetrofosmin scintigraphy improves the detection of myocardium with reversible hypoperfusion in patients with a previous myocardial infarction.