Dobutamine technetium-99m tetrofosmin SPECT imaging for the diagnosis of coronary artery disease in patients with limited exercise capacity

Background, Technetium-99m tetrofosmin single photon emission computed tomo graphy (SPECT) imaging is increasingly used in conjunction with exercise an d vasodilator stress test as a means of evaluating coronary artery disease (CAD), Dobutamine stress test is an alternative in patients with limited ex ercise capacity, This study assessed the accuracy of dobutamine-atropine st ress tetrofosmin SPECT as a means of diagnosing and localizing CAD. Methods and Results. We studied 124 patients (mean age, 57 +/- 12 years; 88 men) with limited exercise capacity and suspected CAD with dobutamine (as much as 40 mug/kg/min)-atropine (as much as 1 mg) Tc-99m tetrofosmin SPECT, Resting images were acquired 24 hours after the stress test. Significant C AD was defined as 50% or greater luminal diameter stenosis in 1 or more maj or coronary arteries. Myocardial perfusion abnormalities (fixed and/or reve rsible defects) were detected in 70 of gs patients with CAD and in 10 of th e 36 patients without CAD (sensitivity = 80%, CI, 72 to 87; specificity = 7 2%, CI, 64 to 80; accuracy = 77%, CI, 70 to 85), Sensitivity and accuracy r ates were higher by using the criterion of any defect than by using the cri terion of reversible defects only (80% vs 51 %, P <.0001; 77% vs 60 %, P <. 01, respectively). The sensitivity rate was higher in patients with multive ssel CAD than in patients with single-vessel CAD (88% vs 63%, P <.05). Pati ents with multivessel CAD had a larger stress perfusion defect score (4.5 /- 3.1 vs 2.7 +/- 2.5, P <.01) than patients with single-vessel CAD. Conclusion. Dobutamine stress Tc-99m tetrofosmin SPECT is a useful method f or the diagnosis and localization of CAD in patients with limited exercise capacity. Optimal accuracy of the technique is achieved by using both fixed and reversible perfusion abnormalities for the diagnosis of CAD in patient s without an earlier myocardial infarction.