Technetium 99m-labeled tetrofosmin myocardial tomography in patients with coronary artery disease: comparison between adenosine and dynamic exercise stress testing.

BACKGROUND: Pharmacologic coronary vasodilation with adenosine, combined with myocardial scintigraphy, is a useful test for the diagnosis of coronary artery disease (CAD) in patients unable to exercise. It has been demonstrated recently that exercise 99mTc-labeled tetrofosmin cardiac imaging can be used for the detection of CAD. However, no data are available comparing 99mTc-labeled tetrofosmin adenosine and exercise tests in the same patients. METHODS AND
RESULTS: The results of adenosine and exercise 99mTc-labeled tetrofosmin myocardial tomography were compared in 41 patients (37 men and four women; mean age 53 +/- 8 years) with suspected or known CAD who underwent coronary angiography. All patients were submitted, on separate days, to three injections of 99mTc-labeled tetrofosmin (740 MBq intravenously): one at rest, one during bicycle exercise, and one during adenosine infusion (140 micrograms/kg/min for 6 minutes with injection of 99mTc-labeled tetrofosmin at 4 minutes). A total of 902 myocardial segments were analyzed quantitatively. One patient had normal coronary vessels, 19 patients had single-vessel CAD, 12 patients had two-vessel CAD, and nine patients had three-vessel CAD (> 50% coronary stenosis) on coronary angiography. Adenosine induced a significant increase in heart rate (88 +/- 16 beats/min at peak vs 72 +/- 11 beats/min at rest; p < 0.01). Systolic and diastolic blood pressure was not significantly different after adenosine infusion compared with rest. Double product was 22931 +/- 7039 at peak exercise and 11229 +/- 3413 after adenosine (p < 0.01). Agreement on the presence of abnormal single-photon emission computed tomography by adenosine and exercise was 100% by quantitative analysis. In all segments a significant relationship between exercise and adenosine 99mTc-99m-labeled tetrofosmin uptake was observed (r = 0.90; p < 0.001). Segmental agreement for regional 99mTc-labeled tetrofosmin uptake score between exercise and adenosine was observed in 737 (82%) of the 902 segments (kappa value of 0.66). Concordance between the two studies for identification of perfusion status was observed in 809 (90%) of the segments (kappa value of 0.80). Sensitivity and specificity for detection of stenosed vessels were not different for dynamic exercise stress testing and adenosine 99mTc-labeled tetrofosmin cardiac tomography.
CONCLUSIONS: Despite different hemodynamic effects, adenosine and dynamic exercise 99mTc-labeled tetrofosmin single-photon emission computed tomographic imaging provides similar information in the diagnosis and localization of CAD.