title: Quantification of myocardial iron deposition by two-dimensional speckle tracking in patients with β-thalassaemia major and Blackfan-Diamond anaemia.
abstract: BACKGROUND
  Cardiac disease related to transfusional iron overload is the leading cause of death in patients with β-thalassaemia major. Early myocardial iron deposition predates decreased left ventricular dysfunction and currently is best assessed by cardiac magnetic resonance.
  
  
  METHODS
  Echocardiographic speckle tracking-derived myocardial mechanics were compared with cardiac MRI T2 star (T2*) calculations in 45 chronically transfused patients with β-thalassaemia major or Diamond-Blackfan anaemia (26 retrospectively and an additional 19 for validation). Two groups were studied: patients with presumed cardiac iron overload and interventricular T2* value ≤20 ms (low T2*) and patients with >20 ms (normal T2*). They were compared with a normal control group of 18 age- and gender-matched patients.
  
  
  RESULTS
  Patients with low T2* had a uniform decrease in longitudinal and circumferential strain compared with normal controls (-16±3% vs -20±3% and -20±4% vs -23±5%, respectively; p<0.0005). Peak twist and peak apical rotation were lower in patients with low T2* than in those with normal T2* or normal control patients. Conversely, no significant difference was observed between patients with normal T2* and controls. There was a strong and direct logarithmic correlation between average global longitudinal strain and T2* values (r=-0.68, p=0.0007). Using a cut-off of ≤-17%, global longitudinal strain predicted a T2* value of <20 ms with a sensitivity of 76% and a specificity of 88%.
  
  
  CONCLUSIONS
  Myocardial mechanics offers a simple alternative to cardiac MRI for assessing significant myocardial iron deposition.
authors.affiliation: Toronto General Hospital, 585 University Avenue, Toronto, Ontario, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Garceau
authors.forename: E T
authors.initials: ET
authors.lastname: Nguyen
authors.forename: S
authors.initials: S
authors.lastname: Carasso
authors.forename: H
authors.initials: H
authors.lastname: Ross
authors.forename: J
authors.initials: J
authors.lastname: Pendergrast
authors.forename: G
authors.initials: G
authors.lastname: Moravsky
authors.forename: B
authors.initials: B
authors.lastname: Bruchal-Garbicz
authors.forename: H
authors.initials: H
authors.lastname: Rakowski
mesh_terms: D000328:Adult; D029503:Anemia, Diamond-Blackfan / Q000378:metabolism*; D016022:Case-Control Studies; D003971:Diastole; D004452:Echocardiography; D005260:Female; D006801:Humans; D007501:Iron / Q000378:metabolism; D019190:Iron Overload / Q000378:metabolism*; D018810:Magnetic Resonance Angiography / Q000379:methods; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D015588:Observer Variation; D013312:Stress, Physiological; D013318:Stroke Volume; D013599:Systole; D017086:beta-Thalassemia / Q000378:metabolism*
chemical_list: D007501:Iron