Accuracy of exercise stress technetium 99m sestamibi SPECT imaging in the evaluation of the extent and location of coronary artery disease in patients with an earlier myocardial infarction

Background. This study assessed the accuracy of exercise methoxy isobutyl i sonitrile (MIBI) single photon emission computed tomography (SPECT) in the evaluation of the extent of coronary artery disease (CAD) in patients with an earlier myocardial infarction. Methods and Results. We studied 135 patients (mean age, 57 +/- 10 years; 11 5 men) at a mean of 4.1 years (median, 1 year) after myocardial infarction with symptom-limited bicycle exercise stress and rest MIBI SPECT imaging. C oronary angiography was performed within 3 months. Significant CAD was defi ned as a stenosis of 50% or larger in luminal diameter in 1 or more major c oronary arteries. Myocardial perfusion defects (fixed, reversible, or both) were detected in 107 of the 113 patients with significant CAD and in 10 of the 22 patients w ithout significant CAD (sensitivity, 95%; CI, 91 to 99; specificity, 55%; C I, 46 to 63, and accuracy, 88%; CI, 82 to 94). The specificity rate increas ed to 73% (CI, 65 to 80) by using only reversible perfusion defects as a me ans of predicting CAD. Reversible perfusion abnormalities were more frequen t in patients with multivessel CAD than in patients with single-vessel CAD (51 of 64 [80%] vs 27 of 49 [55%], P < .01). Myocardial perfusion abnormali ties in 2 vascular regions, which is suggestive of multivessel CAD, were de tected in 35 of the 64 patients with and in 9 of the 71 patients without mu ltivessel CAD (sensitivity for detecting CAD in more than one vascular regi on, 55%; CI, 46 to 63, specificity, 87%; CI, 81 to 93, and accuracy, 72%; C I, 64 to 80). The sensitivity rates for the diagnosis of left anterior desc ending coronary artery, left circumflex, and right coronary artery based on any defect were 80%, 70%, and 63%, respectively. The corresponding specifi city rates were 70%, 76%, and 73%, respectively. Conclusions. Exercise MIBI SPECT imaging is an accurate method for the diag nosis and localization of CAD in patients with an earlier myocardial infarc tion. The technique provides a high specificity and moderate sensitivity fo r the diagnosis of multivessel CAD on the basis of myocardial perfusion abn ormalities in more than 1 vascular region.