Value of ECG-gated Thallium-201 Dipyridamole SPECT in Borderline Cases of Myocardial Perfusion Scan

Background: Thallium-201 myocardial perfusion scan is a commonly utilized method for detection of coronary artery disease. Although this technique is generally reliable, results can be inconclusive in some cases. The purpose of this study was to assess whether candidates for coronary angiogram could be better identified with the addition of an electrocardiographic (ECG)-gated myocardial perfusion scan to a thallium scan. Method: A total of 512 patients with suspected coronary artery disease were included in this study and received a thallium scan. In 69 patients, the results were borderline, and 32 of these 69 patients also received an ECG-gated scan and underwent coronary angiogram within one month. Results: We found that 21 of the 32 patients who underwent coronary angiogram had significant coronary artery disease. However, when an ECG-gated perfusion scan was also performed, 25 of the 32 patients had abnormal regional wall motion following the stress test. Twenty-one of these 25 patients were found to have significant coronary artery disease. Statistical analysis revealed that the ECG-gated perfusion scan in combination with the thallium scan was significantly more accurate than the thallium scan alone in borderline cases of myocardial perfusion scan (p = 0.0166), with 100% sensitivity, 63.6% specificity, an 84% positive predictive rate, and a 100% negative predictive rate. Conclusions: The ECG-gated perfusion scan in combination with a thallium scan was more accurate in predicting the presence of coronary artery disease than a thallium scan alone in borderline cases of myocardial perfusion scan.