Myocardial deformation in patients with Beta-thalassemia major: a speckle tracking echocardiographic study.

BACKGROUND: Increasing data suggest that parameters of myocardial deformation are strong indices of ventricular systolic and diastolic function. We sought to determine myocardial deformation of the left ventricle and assess relationship of deformation rates with myocardial iron load in patients with beta-thalassemia major.
METHODS: The left ventricular longitudinal, circumferential, and radial myocardial deformation was determined using speckle tracking echocardiography in 42 thalassemia patients aged 24.4 +/- 6.4 years. The results were compared with those of 38 age-matched controls. The rates of longitudinal and circumferential deformation were correlated with cardiac T2* magnetic resonance findings.
RESULTS: Compared with controls, patients had significantly greater global systolic radial strain (P = 0.001), but similar global systolic longitudinal (P = 0.12) and circumferential strain (P = 0.84). On the other hand, patients had significantly lower longitudinal systolic strain rate (SR) (P = 0.019), longitudinal early diastolic SR (P = 0.036), and circumferential early diastolic SR (P = 0.04) than controls. The cardiac T2* findings correlated positively with longitudinal (r = 0.44, P = 0.004) and circumferential early diastolic SR (r = 0.37, P = 0.019), but not with the respective systolic SRs and left ventricular ejection fraction (all P > 0.05). Patients with iron overload (T2*< 20 msec), compared to those without, had significantly lower longitudinal (1.45 +/- 0.33/sec vs. 1.76 +/- 0.27/sec, P = 0.002) and circumferential (1.01 +/- 0.31/sec vs. 1.22 +/- 0.31/sec, P = 0.03) early diastolic SR.
CONCLUSIONS: Patients with beta-thalassemia major have reduced longitudinal systolic SR, longitudinal early diastolic SR, and circumferential early diastolic SR. The rates of diastolic deformation in the longitudinal and circumferential dimensions are inversely related to myocardial iron overload.