title: Role of Three-Dimensional Speckle Tracking Echocardiography in the Quantification of Myocardial Iron Overload in Patients with Beta-Thalassemia Major.
abstract: BACKGROUND
  The new three-dimensional speckle tracking echocardiography (3DSTE) may enable comprehensive quantification of global left ventricular (LV) myocardial mechanics.
  
  
  METHODS
  Twenty-four patients aged 29.3 ± 5.2 years and 22 controls were studied. 3DSTE was performed to assess LV 3D global strain, twist and torsion, ejection fraction, and systolic dyssynchrony index (SDI). The LV SDI was calculated as % of SD of times-to-peak strain of 16 segments/RR interval. The global performance index (GPI) was calculated as (global 3D strain·torsion)/SDI. Area under the receiver operating characteristic curve (AUC) was calculated to determine the capability of 3DSTE parameters to discriminate between patients with (cardiac magnetic resonance T2* <20 ms) and those without myocardial iron overload.
  
  
  RESULTS
  Compared with controls, patients had significantly lower LV global 3D strain (P < 0.001), twist (P = 0.01), torsion (P = 0.04), and ejection fraction (P < 0.001) and greater SDI (P < 0.001). The GPI was lower in patients than controls (P < 0.001). T2* value correlated positively with global 3D strain (r = 0.74, P < 0.001) and GPI (r = 0.63, P = 0.001), and negatively with SDI (r = -0.44, P = 0.03). The AUCs of GPI, global 3D strain, ejection fraction, torsion, and 1/SDI were 0.94, 0.90, 0.87, 0.82, and 0.70, respectively. The GPI cutoff of 2.7°/cm had a sensitivity of 94.9% and a specificity of 88.9% of differentiating patients with from those without myocardial iron overload.
  
  
  CONCLUSIONS
  The LV composite index of strain, torsion, and dyssynchrony derived from 3DSTE enables sensitive detection of myocardial iron overload in patients with thalassemia.
authors.affiliation: Division of Pediatric Cardiology, Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong, China.|The First Affiliated Hospital of Sun Yat-sen University, Guangdong, China.
authors.forename: Shu-Juan
authors.initials: SJ
authors.lastname: Li
authors.affiliation: Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong, China.
authors.forename: Yu-Yan
authors.initials: YY
authors.lastname: Hwang
authors.affiliation: Division of Pediatric Cardiology, Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: Shau-Yin
authors.initials: SY
authors.lastname: Ha
authors.affiliation: Division of Pediatric Cardiology, Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: Godfrey C F
authors.initials: GC
authors.lastname: Chan
authors.affiliation: Division of Pediatric Cardiology, Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: Amanda S P
authors.initials: AS
authors.lastname: Mok
authors.affiliation: Division of Pediatric Cardiology, Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: Sophia J
authors.initials: SJ
authors.lastname: Wong
authors.affiliation: Division of Pediatric Cardiology, Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong, China. xfcheung@hku.hk.
authors.forename: Yiu-Fai
authors.initials: YF
authors.lastname: Cheung
mesh_terms: D000328:Adult; D019560:Echocardiography, Three-Dimensional / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D019190:Iron Overload / Q000000981:diagnostic imaging* / Q000209:etiology; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology; D017086:beta-Thalassemia / Q000150:complications / Q000000981:diagnostic imaging*
keywords: 3D speckle tracking; iron overload; thalassemia