title: Irbesartan has a masking effect on dipyridamole stress induced myocardial perfusion defects.
abstract: OBJECTIVE
  The angiotensin II type 1 (AT1) receptor antagonist irbesartan is used for the treatment of hypertension, but its anti-ischaemic effect is not yet known. Our aim was to assess the effect of irbesartan administration on the diagnostic yield of 99mTc sestamibi single photon emission computed tomography (SPECT) in patients with coronary artery disease (CAD) after dipyridamole stress.
  
  
  METHODS
  Our study group consisted of 13 patients (11 men and two women; mean age, 53.3 +/- 10.6 years; body mass index, 26.9 +/- 3.3 kg x m(-2)) with angiographically documented CAD. All patients underwent SmTc sestamibi SPECT studies at rest, before (STRESS-1) and 2 weeks after irbesartan (150 mg daily) administration (STRESS-2) at dipyridamole stress. The extent and severity of defects were analysed by using visual and quantitative 99mTc sestamibi SPECT.
  
  
  RESULTS
  The mean summed stress score was significantly higher during the STRESS-1 study than the STRESS-2 study (13.2 +/- 7.4 vs. 11 +/- 7.4, P=0.003). The mean size of perfusion defects at stress was significantly larger for the STRESS-1 group than the STRESS-2 group (17.8% +/- 2.85% vs. 15.3% +/- 2.95%, P=0.01).
  
  
  CONCLUSIONS
  Our study showed that the AT1 receptor blocker irbesartan reduces the extent and severity of 99mTc sestamibi perfusion defects after dipyridamole stress in patients with CAD. Irbesartan may alter coronary blood flow reserve. The continued use of irbesartan before stress myocardial perfusion SPECT has a masking effect on stress induced myocardial perfusion defects. For this reason AT1 receptor blockers must be stopped before stress myocardial perfusion scintigraphic examinations.
authors.affiliation: Trakya University, Faculty of Medicine, Department of Nuclear Medicine, Edirne, Turkey. gdurmusaltun@trakya.edu.tr
authors.forename: Gulay Durmus
authors.initials: GD
authors.lastname: Altun
authors.forename: Armagan
authors.initials: A
authors.lastname: Altun
authors.forename: Mustafa
authors.initials: M
authors.lastname: Yildiz
authors.forename: Mehmet F
authors.initials: MF
authors.lastname: Firat
authors.forename: Sevim
authors.initials: S
authors.lastname: Hacimahmutoglu
authors.forename: Sakir
authors.initials: S
authors.lastname: Berkarda
mesh_terms: D000328:Adult; D047228:Angiotensin II Type 1 Receptor Blockers; D000959:Antihypertensive Agents / Q000009:adverse effects*; D001713:Biphenyl Compounds / Q000009:adverse effects*; D001794:Blood Pressure / Q000187:drug effects; D003326:Coronary Circulation / Q000187:drug effects*; D004176:Dipyridamole; D005260:Female; D015637:Gated Blood-Pool Imaging; D006321:Heart / Q000000981:diagnostic imaging*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D000077405:Irbesartan; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals; D013312:Stress, Physiological / Q000139:chemically induced* / Q000000981:diagnostic imaging*; D017256:Technetium Tc 99m Sestamibi; D013777:Tetrazoles / Q000009:adverse effects*; D015899:Tomography, Emission-Computed, Single-Photon; D014665:Vasodilator Agents; D016277:Ventricular Function, Left
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D000959:Antihypertensive Agents; D001713:Biphenyl Compounds; D019275:Radiopharmaceuticals; D013777:Tetrazoles; D014665:Vasodilator Agents; D004176:Dipyridamole; D017256:Technetium Tc 99m Sestamibi; D000077405:Irbesartan