Technetium-99m-tetrofosmin imaging with incremental nitroglycerin infusion to detect severely ischaemic but viable myocardium: a comparative study with thallium-201???

Abstract

The aim of this study was to assess the influence of incremental nitroglycerin infusion (NTG+Inf) on the myocardial uptake of 99mTc-tetrofosmin (TF) in order to determine whether nitrates enhance the detection of viable myocardium with TF in patients with coronary artery disease (CAD) and left ventricular dysfunction. Fifty patients (39 males, 11 females; 54 +/- 11 years) with previous myocardial infarction and left ventricular dysfunction, who had been referred for coronary revascularization procedures, were studied. Myocardial single-photon emission tomography (SPET) images were obtained 1 h after injection of 750 MBq TF at baseline and after NTG+Inf, using a 2 day protocol. NTG+Inf was performed starting at 0.4 microg x kg(-1) x min(-1), with equal increments every 5 min up to 2 microg x kg(-1) x min(-1). Within 1 week of the TF study, rest-redistribution (R-RD) 201Tl SPET was performed after the injection of 111 MBq 201Tl. For each study, quantitative analysis was performed in 17 segments. Viability was defined as the presence of tracer uptake of > 50% of the peak activity on baseline studies or reversibility. There was significant correlation between quantitative regional RD 201Tl activity and TF activity after NTG+Inf (r = 0.90, P < 0.001). Of the 131 segments with severely reduced tracer uptake on resting TF images, 34 (26%) were reversible, showing increased tracer uptake after NTG+Inf (from 41%+/-7% to 57%+/-12% of peak activity; P < 0.001). All reversible segments after NTG+Inf had viability criteria on 201Tl studies. There was 95% concordance between TF with NTG+Inf and RD 201Tl imaging with regard to the presence of myocardial viability. We conclude that TF imaging with incremental NTG+Inf improves the detection of ischaemic but viable myocardium, correlating with the viability criteria observed on 201Tl studies. When the advantages of TF imaging are considered, rest TF imaging with NTG+Inf may be a practical diagnostic protocol in patients with CAD and left ventricular dysfunction who are being considered for revascularization.

The Effects of Medications on Myocardial Perfusion

“…In positron emission tomography (PET) studies, pre-treatment with nitrates increased tracer uptake in the ischemic myocardium compared with that in the nonviable myocardium, resulting in improved viability detection (31,32). Pre-treatment with nitrates improved detection of viable myocardium and predicted post-revascularization recovery in different studies that used resting MPI with the technetium-labeled tracers (tetrofosmin, sestamibi) and with thallium-201 (33)(34)(35)(36)(37)(38)(39)(40). In patients with ischemic cardiomyopathy, the prognostic value of SPECT MPI after nitrate was comparable to that of PET imaging (40).…”

Effects of nitroglycerine on coronary flow velocity before and during adenosine provocation

“…This hypothesis was based on the known vasodilating effects of nitroglycerine on epicardial arteries and clinical experiences from fractional flow reserve (FFR) measurements and myocardial scintigraphy where pretreatment with NTG may be used to enhance hyperemia [20–22]. …”

Myocardial perfusion scintigraphy in the prediction of the existence of hemodynamically significant coronary artery stenosis

“…On the first day, a study was performed with the application of radiopharmaceuticals immediately after the end of the physical load test, in the dose of 20 mCi, while on the second day, a study was done at rest with the same dose of radiopharmaceutical. In patients in whom perfusion defects were recorded on the stress study, when performing the study at rest, 5 minutes before the application of radiopharmaceuticals, the diagnostic application of a coronary dilator (Nitrolingual-Spray, G. Pohl-Boskamp GmbH & Co, KG, Kieler Strasse 11, Hohenlockstedt, Germany) in the dose of 0.4 to 0.8 mg was done to assess the viability of the myocardium affected by ischemia (8,9).…”