Adenosine technetium-99m-methoxy isobutyl isonitrile myocardial tomography in patients with coronary artery disease: Comparison with exercise

We compared the results of adenosine and bicycle exercise ^99mTc- methoxy isobutyl isonitrile (MIBI) myocardial SPECT in 22 patients (18 males and 4 females, mean age 51 ± 11 yr) with angiographically documented coronary artery disease (CAD). Methods: All patients were submitted on separate days to three intravenous injections of ^99mTc-MIBI (20 mCi); one at rest, one during exercise and one during adenosine (140 μg/kg per min for 6 min with injection of ^99mTc-MIBI at 4 min). A total of 484 myocardial segments were quantitatively analyzed. Results: Adenosine induced a significant increase of heart rate (94 ± 16 bpm at peak versus 70 ± 13 bpm at rest, p <0.01). Systolic and diastolic blood pressure were not significantly different after adenosine infusion compared to rest. In all segments, a significant relationship between exercise and adenosine ^99mTc- MIBI uptake was observed (r = 0.90, p <0.0001). Concordance between the two studies for identification of perfusion status was observed in 438 (90%) of the 484 segments (kappa value of 0.81). Agreement on localization of the perfusion defect to a specific vascular territory was 92%. Conclusion: Despite different hemodynamic effects, adenosine and exercise ^99mTc-MIBI SPECT imaging provide similar information in the diagnosis and localization of CAD.