COMPARISON OF EXERCISE AND ADENOSINE TC-99M SESTAMIBI MYOCARDIAL SCINTIGRAPHY FOR DIAGNOSIS OF CORONARY-ARTERY DISEASE IN PATIENTS WITH LEFT-BUNDLE-BRANCH BLOCK

False-positive exercise thallium tests occur in approximately 80% of symptomatic patients with left bundle branch block (BBB) and normal coronary arteries.1 It has been suggested that the low specificity of thallium scintigraphy in patients with left BBB may be due to a heart rate-dependent decrease in coronary blood flow through compression of septal perforator arteries. Adenosine has been proposed as an alternative to exercise stress with thallium-201 perfusion imaging2-4 for the diagnosis of coronary artery disease (CAD). Adenosine produces maximal or near-maximal coronary vasodilation in 92% of patients,5 its short half-life obviates the need for theophylline, and it is reported to increase heart rate only slightly.6 We proposed that combining adenosine, whose diagnostic efficacy is less dependent on increases in heart rate, with technetium (Tc)-99m sestamibi imaging would provide improved specificity for the detection of CAD in patients with left BBB. © 1993.