Exercise-induced left bundle branch block during thallium 201 myocardial perfusion scintigraphy - A case report

Exercise-induced left bundle branch block (Ex-LBBB) is a rare entity encoun tered during exercise testing. The authors present a 53-year-old woman who developed intermittent Ex-LBBB asymptomatically during TI 201 myocardial pe rfusion scintigraphy. Scintigraphic findings revealed septal-anteroseptal i schemia while the coronary arteriogram appeared normal. False-positive sept al-anteroseptal scintigraphic findings suggesting ischemia in patients with persistent left bundle branch block (LBBB) is well known, but since the LB BB in this case was induced by exercise testing and was spontaneously termi nated at rest. scintigraphic findings may be attributed to microcirculatory ischemia, which cannot be detected angiographicaily, as the cause of Ex-LB BB.