title: Exercise-induced myocardial perfusion abnormalities in sickle beta-thalassemia: Tc-99m tetrofosmin gated SPECT imaging study.
abstract: OBJECTIVE
  To determine the mechanism of myocardial ischemia in patients with sickle beta-thalassemia, we performed a scintigraphic evaluation of myocardial perfusion during exercise.
  
  
  METHODS
  We studied 30 patients with sickle beta-thalassemia, (mean [+/-SD] age, 37 +/- 10 years) who had no electrocardiographic (ECG), radiographic, or echo-Doppler signs of pulmonary hypertension, left ventricular hypertrophy, or impaired contractility. All patients had a hemoglobin level greater than 7 g/dL. Treadmill exercise test was performed according to the Bruce protocol. Myocardial perfusion was assessed by single-photon emission computed tomography, using Tetrofosmin Tc-99 m Myoview as radiotracer, at peak exercise and again 4 hours later.
  
  
  RESULTS
  Eight patients (27%) developed stress-induced scintigraphic perfusion abnormalities that were reversible in all but 1 patient. Subsequent coronary angiograms were normal in all 8 patients. ST segment depression was seen during exercise in 5 of the 7 patients who had reversible perfusion defects. Except for a significantly greater white blood cell count, these 5 patients did not differ from the rest of patients by sex, age, hemoglobin level, percentage hemoglobin F, beta-thalassemia genotype, or risk factors for coronary artery disease. Three of the 5 patients with perfusion and ECG abnormalities (and another with only perfusion defects) developed a stress-induced sickling crisis.
  
  
  CONCLUSIONS
  Physical stress may induce myocardial ischemia in sickle beta-thalassemia patients with normal coronary arteries and elicit painful crises. The sickling process, activated by exercise, could be the common underlying mechanism.
authors.affiliation: First Department of Medicine, University of Athens, Medical School, Laiko Hospital, Athens, Greece.
authors.forename: A
authors.initials: A
authors.lastname: Aessopos
authors.forename: M
authors.initials: M
authors.lastname: Tsironi
authors.forename: I
authors.initials: I
authors.lastname: Vassiliadis
authors.forename: D
authors.initials: D
authors.lastname: Farmakis
authors.forename: A
authors.initials: A
authors.lastname: Fountos
authors.forename: E
authors.initials: E
authors.lastname: Voskaridou
authors.forename: A
authors.initials: A
authors.lastname: Perakis
authors.forename: S
authors.initials: S
authors.lastname: Defteraios
authors.forename: A
authors.initials: A
authors.lastname: Loutradi
authors.forename: D
authors.initials: D
authors.lastname: Loukopoulos
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000755:Anemia, Sickle Cell / Q000503:physiopathology*; D003326:Coronary Circulation; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D018709:Statistics, Nonparametric; D015899:Tomography, Emission-Computed, Single-Photon; D017086:beta-Thalassemia / Q000503:physiopathology*
chemical_list: D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C078700:technetium tc-99m tetrofosmin