LIMITS OF TL-201 EXERCISE SCINTIGRAPHY TO DETECT CORONARY-DISEASE IN PATIENTS WITH COMPLETE AND PERMANENT BUNDLE-BRANCH BLOCK - A REVIEW OF 134 CASES

We reviewed the records of 68 patients with right bundle branch block (RBBB) and 66 patients with left bundle branch block (LBBB), who had undergone thallium-201 exercise scintigraphy and coronary arteriography, to determine the sensitivity, specificity, and positive and negative predictive values of thallium-201 imaging for the detection of coronary artery disease in the Presence of intraventricular conduction abnormalities. In patients with RBBB the sensitivity, specificity, and positive and negative predictive values were, respectively, 83%, 89%, 79%, and 92% for the anteroseptal region and 83%, 84%, 83%, and 84% for the inferoposterior region. In patients with LBBB these values were, respectively, 94%, 33%, 36%, and 93% for the anteroseptal region and 77%, 90%, 81%, and 88% for the inferoposterior region. In this second group defects limited to the septal region were a good predictor of false positive scintigrams (9/10 cases), but if apical defects used as the sole criterion for detecting lesions in the left anterior descending artery improved the specificity to 85%, the sensitivity was greatly reduced (35%). We conclude that exercise scintigraphy is a reliable method for detection of coronary lesions in patients with RBBB and in patients with LBBB and inferoposterior perfusion defects, but it is unable to discriminate between normal subjects and patients with coronary disease in the presence of LBBB and anteroseptal perfusion defects. In addition, limited septal defects are highly suggestive of false positive scintigrams in this latter group of patients.