Introduction: Myocardial iron overload leading to congestive heart failure (HF) or arrhythmias is a recognized complication in thalassemia patients undergoing chronic blood transfusion. The relationship between myocardial iron load, subclinical systolic dysfunction, and clinical events remains less well known.
Materials and methods: We studied a total of 77 subjects, comprising 37 thalassemia patients (mean age: 24.2 ± 5.5 years) with a history of repeated blood transfusions, in addition to 40 age- and gender-matched controls (mean age: 24 ± 4.5 years). Serum ferritin levels were checked in all subjects, as well as semiautomated quantification of left ventricular (LV) longitudinal, circumferential, and radial deformations assessed by two-dimensional (2D) speckle tracking analysis.
Results: Compared with the control group, thalassemia patients showed significantly larger LV mass index and lower myocardial deformations (P < 0.05), but left ventricular ejection fraction (LVEF) did not differ significantly (P = 0.233). There was a significant linear correlation between serum ferritin level and longitudinal (r = 0.44, P = 0.0078) and radial strain (r = -0.46, P = 0.0051), with optimal cutoff provided to be -15.48%, -21.31%, and 26.67% for longitudinal, circumferential, and radial strain in predicting clinical events, respectively. During a median of 802.5 days follow-up, 11 clinical composites (HF incidence, ventricular tachyarrhythmia, and death) occurred (N = 9 subjects); subjects with composites had significantly reduced longitudinal and radial strain compared to those without (both P < 0.05). After adjusting for age, sex, serum ferritin level, and LV mass index, a worsening of longitudinal strain remained as an independent predictor of clinical events and death (HR: 6.05, P = 0.033).
Conclusion: Subclinical systolic dysfunction appears more likely in thalassemia subjects with a history of repeated blood transfusions, which further correlated with serum ferritin levels. In addition, worsening LV myocardial deformation parameters may play an independent role in predicting clinical outcomes beyond traditional measures in this population.
Keywords: echocardiography; myocardial deformation imaging; thalassemia.
© 2014, Wiley Periodicals, Inc.