[Improved detection of fill-in using sublingual nitroglycerin in technetium-99m tetrofosmin exercise/rest single...

This study assessed the effect of sublingual nitroglycerin administered before rest imaging in the technetium-99m (99mTc) tetrofosmin exercise and rest same day protocols to determine whether the use of nitroglycerin improved the detection of fill-in the rest single photon emission computed tomography (SPECT) images 3 hours after peak exercise. Twenty-one patients with old myocardial infarction underwent repeated 99mTc-tetrofosmin exercise/rest same day protocols with and without the administration of sublingual nitroglycerin (0.3 mg) 5 min before the second injection of 99mTc-tetrofosmin for rest SPECT imaging. Twelve of these patients also underwent ordinary exercise/redistribution 201T1 SPECT imaging. The control study protocol images showed decreased uptake of 99mTc-tetrofosmin on exercise in 157 of 420 segments and the presence of fill-in at rest in 58 segments. Images obtained with administration of nitroglycerin showed decreased uptake of 99mTc-tetrofosmin on exercise in 163 of 420 segments and fill-in in 74 segments at rest. The frequency of fill-in was greater in the nitroglycerin protocol than in the control protocol (p < 0.05). The segments were scored as different grades according to 99mTc-tetrofosmin uptake between 2 protocols. Fill-in was only present or more remarkable in 31 segments in the nitroglycerin protocol than in the control protocol. Fill-in was only present or more remarkable in 10 segments in the control protocol than in the nitroglycerin protocol. In the nitroglycerin protocol, the mean defect score of the exercise images, calculated from the bull's eye image automatically, was higher than that of the rest images (121 +/- 40 vs 94 +/- 53, p < 0.01). The mean severity score of the exercise images, also calculated from the bull's eye image automatically, was likewise higher than that of the rest images (691 +/- 382 vs 524 +/- 431, p < 0.01), whereas the mean severity score of the stress images and rest images in the control protocol was not significantly different. Moreover, the mean defect score and severity score of the rest images from the nitroglycerin protocol were significantly lower than those obtained from the control protocol (p < 0.05). Sublingual nitroglycerin administration before the injection of 99mTc-tetrofosmin at the rest study in the one day exercise/rest studies enhanced fill-in, so may enhance the detection of viable myocardium, allowing more informed decisions regarding cardiac revascularization in patients with chronic coronary artery disease.