Accuracy of dobutamine technetium 99m sestamibi SPECT imaging for the diagnosis of single-vessel coronary artery disease: Comparison with echocardiography

Background Recent experimental studies have shown that technetium 99m metho xyisobutyl isonitrile (MIBI) underestimates flow heterogeneity induced by d obutamine and that this might have an impact on the sensitivity of dobutami ne MIBI in patients with single-vessel coronary artery disease (CAD). This study compares the accuracy of dobutamine MIBI single-photon emission compu ted tomography (SPECT) and simultaneous echocardiography in the diagnosis o f single-vessel CAD, Methods and Results Ninety-one patients (age 57 +/- 12 years) with single-v essel CAD or without significant CAD were studied with dobutamine (up to 40 mu g/kg per minute)-atropine (up to 1 mg) stress echocardiography (DSE) an d simultaneous MIBI SPECT imaging. CAD was predicted on the basis of myocar dial ischemia (transient wall motion abnormalities by DSE and reversible pe rfusion defects by MIBI). Ischemia was detected by MIBI in 30 of the 54 pat ients with and in 10 of the 37 patients without significant single-vessel C AD (sensitivity 56%, confidence interval [CI] 45 to 66; specificity 73%, CI 64 to 82; accuracy 63%, CI 53 to 73). Ischemia was detected by DSE in 30 p atients with and in 6 patients without significant CAD (sensitivity of DSE 56%, CI 45 to 66; specificity 84%, CI 76 to 91; accuracy 67%, CI 57 to 77, P = not significant vs MIBI). For both imaging methods, sensitivity was sig nificantly higher in patients with left anterior descending than in patient s with left circumflex or right coronary artery stenosis (75% vs 40%, P < . 05). The addition of echocardiography to MIBI did not improve the diagnosti c accuracy (68% CI 59 to 78, P = not significant vs DSE or MIBI alone). Conclusions DSE and MIBI SPECT imaging have similar moderate sensitivity Fo r the diagnosis of single-vessel CAD. Sensitivity of each of these techniqu es is higher in patients with left anterior descending than in patients wit h left circumflex or right coronary artery stenosis. There is no improvemen t of diagnostic accuracy by use of the combination of both techniques.