False-positive results obtained with stress myocardial SPECT in patients with right bundle branch block

PURPOSE: Right bundle branch block (RBBB) is a conduction defect that often is accompanied by nonspecific patient symptoms. The objective of this study was to evaluate the false-positive results obtained with TI-201 myocardial SPECT in patients with RBBB. METHODS: Thirty-one patients (24 men, 7 women; age range, 35 to 78 years; mean age, 39 +/- 14 years) had nonspecific chest pain and electrocardiograph-proved RBBB, normal results of echography, and normal results of coronary angiography. None of them had a previous history or evidence of myocardial infarction. All patients underwent stress-rest TI-201 myocardial SPECT; 24 had normal images but 7 showed hypoperfusion in the inferolateral segments, both visually and quantitatively. RESULTS: TI-201 myocardial perfusion scintigraphs must be evaluated carefully in RBBB because false-positive results are likely to occur as a result of functional changes produced by dissynchronous activation between the ventricles.