DOBUTAMINE TL-201 MYOCARDIAL SPECT IN PATIENTS WITH LEFT-BUNDLE-BRANCH BLOCK AND NORMAL CORONARY-ARTERIES

Dobutamine is a positive inotropic and chronotropic agent and is being widely used as a pharmacologic stress agent in patients unable to ach ieve maximal dynamic exercise test. The purpose of the current study w as to document the dobutamine induced false-positive septal defect in terms of its frequency and extent on Tl-201 myocardial SPECT in patien ts with left bundle branch block (LBBB). Methods: Twenty-five symptoma tic patients with LBBB underwent dobutamine and redistribution Tl-201 myocardial SPECT studies. Coronary angiographies were also performed. Only those patients with normal coronaries(n = 19) were included in th e study. For each study, tomograms were divided into 19 segments, and each segment was analyzed qualitatively as to presence and type of per fusion defect (reversible or fixed), In addition, septal perfusion was scored in each patient (1 = markedly, 2 = moderately reduced, 3 = nor mal uptake). Results: Sixteen of 19 patients (84.21%) had false-positi ve septal reversible perfusion defect, and the remaining 3 had normal images. Perfusion defects were confined to only the septum in 5 of 16 patients (31.25%), whereas a greater proportion of patients had septal defect extending to the contiguous myocardial areas, mainly to the an terior wall, Five of 16 patients with false-positive defects had a sep tal perfusion score of I, while the remaining 1 1 had a score of 2. Co nclusion: Dobutamine myocardial scintigraphy in patients with LBBB was misleading for the diagnosis of coronary artery disease, since up to 84.21% of patients had false-positive septal perfusion defects.