title: 99mTc-MIBI stress-rest myocardial perfusion scintigraphy in patients with complete left bundle branch block.
abstract: BACKGROUND
  Patients with complete left bundle branch block (LBBB) often show a false-positive ischaemic pattern in the interventricular septum on thallium-201 (201TI) stress-rest myocardial perfusion scintigraphy. Equivocal results have been reported with technetium-99m labelled hexakis-methoxyisobutyl isonitrile (99mTc-MIBI) in such patients. The aim of this retrospective study was to determine the effect of LBBB on the septal uptake of 99mTc-MIBI during stress-rest single photon emission computed tomography (SPECT) scintigraphy.
  
  
  METHODS
  We studied 75 consecutive patients with LBBB, referred for 99mTc-MIBI stress-rest SPECT. Studies were evaluated by visual analysis using a semi-quantitative grading technique. In all patients with abnormal septal segments, the presence or absence of ischaemic heart disease was confirmed either clinically or by means of angiographical examination.
  
  
  RESULTS
  Forty-three patients (57.3%) had completely normal studies. Only 15 (20%) had septal abnormalities (11 with reversible and 4 with fixed defects), while 17 patients (22.7% had abnormal segments in areas other than the interventricular septum. Except for 1 patient lost to follow-up, ischaemic heart disease was confirmed in all the patients with septal changes.
  
  
  CONCLUSIONS
  We conclude that 99mTc-MIBI is more specific than 201TI for identifying ischaemic heart disease in the presence of LBBB.
authors.affiliation: Department of Nuclear Medicine, University of Stellenbosch, Tygerberg, Western Cape, South Africa.
authors.forename: A
authors.initials: A
authors.lastname: Ellmann
authors.forename: P D
authors.initials: PD
authors.lastname: van Heerden
authors.forename: B B
authors.initials: BB
authors.lastname: van Heerden
authors.forename: J F
authors.initials: JF
authors.lastname: Klopper
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002037:Bundle-Branch Block / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology; D017023:Coronary Angiography; D005080:Exercise Test; D005500:Follow-Up Studies; D006321:Heart / Q000000981:diagnostic imaging*; D006343:Heart Septal Defects / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology; D010477:Perfusion; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D017256:Technetium Tc 99m Sestamibi; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi