Reevaluation of the accuracy of exercise and dipyridamole thallium-201 myocardial SPECT for detecting myocardial ischemia

To reevaluate the accuracy of stress thallium-201 (Tl) myocardial SPECT, 100 subjects with ischemic heart disease underwent coronary arteriography (CAG), left ventriculography (LVG) and 2 D-echocardiography (2D-ECHO) and were classified into 2 groups ; the patient group examined by Tl myocardial SPECT following intravenous administration of dipyridamole (DIP Tl-SPECT ; n=50), and another patient group studied by Tl myocardial SPECT using exercise testing with bicycle ergometer (EX Tl-SPECT ; n=50). Significant coronary lesions were defined as exceeding 75% luminal diameter narrowing in CAG with viable ventricular wall motion in LVG or 2D-ECHO. Although the sensitivity and specificity for detecting myocardial ischemia were 60.4% and 94.2% in DIP Tl-SPECT, and were 83.7% and 91.6% in EX Tl-SPECT. The sensitivity of Tl imaging in EX Tl-SPECT was significantly higher than that in DIP Tl-SPECT. In both two groups, the sensitivity for ischemic lesion of left anterior descending branch was higher than those of left circumflex branch and right coronary artery. The positive and negative predictive values were both about 80% in DIP Tl-SPECT and both about 90% in EX Tl-SPECT respectively. The sensitivity of EX Tl-SPECT for detecting myocardial ischemia is relatively higher than that of DIP Tl-SPECT, but DIP Tl-SPECT may provide a useful alternative test for potential coronary artery disease patients unable to perform the exercise testing. (author)