Assessment of left ventricular and atrial diastolic function using two-dimensional (2D) strain imaging in patients with β-thalassemia major

摘要

Background: β-thalassemia major is a unique disease characterized by early severe diastolic dysfunction, due to iron myocardial deposition alone, while left ventricular systolic dysfunction and failure seem to be multifactorial in aitiology. Objectives: The purpose of this study was to investigate left ventricular diastolic dysfunction using a new echo index as speckle tracking in comparison with the conventional methods. Material and methods: Eighty-eight consecutive patients (38 male, 50 female) aged 36 ± 8.2 yr with β-thalassemia major and preserved LV ejection fraction (LVEF>55%) were studied. Patients were divided into two groups according to the E mitral/E mitral annulus ratio (E/E'): group A patients with E/E' ratio ≤8 and group B patients with E/E' >8. Cutoff value of eight was used to separate patients with normal and abnormal diastolic function. All subjects were studied thoroughly by tissue Doppler echocardiography as also by 2D left ventricular and atrial strain imaging 2-4 d following blood transfusion. Blood samples were also taken for plasma BNP measurements at the same time. Results: Left atrial volumes(LAV max, LAV min) as also left atrial index were significantly higher in patients with diastolic dysfunction compared with patients without diastolic dysfunction(LAV max: 57.6 ± 19.4 vs. 71.3 ± 22.9, P < 0.01,LAV min: 20.2 ± 11.4 vs. 33.9 ± 18, P < 0.01, LAVI: 37.66 ± 12.18 vs. 47.13 ± 14.77, P < 0.01). Radial 2D strain (RS) and peak atrial 2D strain (AS) were significantly reduced in patients with suspected diastolic dysfunction compared with patients without diastolic dysfunction (RS: 43.48 ± 13.92 vs. 35.58 ± 11.32, P < 0.05; AS: 36.36 ± 8.45 vs. 29.85 ± 9.25, P < 0.01). Using ROC analysis, peak atrial 2D strain at a cutoff of 41.1 cm/s was highly accurate (AUC: 0.66, P < 0.05 in ruling out diastolic dysfunction (E/E'<8) with a sensitivity of 90% and a specificity of 81%. Conclusions: B-thalassemic major patients with preserved left ventricular systolic function had impaired left atrial function at the longitudinal axis and left ventricular function at the radial axis. The new echo markers have better prognostic value than the traditional echo indexes in detecting latent diastolic dysfunction in β-thalassemia major, earlier than E/E' ratio.