Augmentation of Left Atrial Contractile Function: A Herald of Iron Overload in Patients with Beta Thalassemia Major

Abstract

Early detection of myocardial iron overload is crucial for optimal management of patients with beta thalassemia major, which could lead to intensification of iron chelating therapy. In this study, we evaluate the conventional echocardiography and tissue Doppler imaging measurements in patients with beta thalassemia major and further introduce the assessment of atrial ejection force as a feasible price-saving approach for early detection of myocardial iron overload. During a 1-year period, 42 cases of beta thalassemia major aged <21 years and with preserved systolic function were evaluated with magnetic resonance T2* imaging (MRI T2*), conventional echocardiography, and tissue Doppler imaging techniques. Patients were classified into two groups according to their myocardial MRI T2* values, with and without critical iron loading. All patients with echocardiographic evidence of moderate and severe stages of diastolic dysfunction showed critical iron loading in their MRI T2*. After excluding those patients with severe and moderate ventricular diastolic filling abnormality, the atrial ejection force index (P = 0.002) and a number of volume indexes of the left atrium showed a significant difference between the two groups. None of the tissue Doppler imaging measurements showed a statistically significant difference between the two groups. The atrial ejection force index of 7.41, with a sensitivity of 93% and a specificity of 74%, was suggested to detect critical cardiac iron loading. These results imply that combining the atrial ejection force index with the transmitral-derived echocardiographic assessment is a feasible way to detect early stages of myocardial iron overload in patients with beta thalassemia major.

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Contribution of left atrial volume and function in neurocardiogenic syncope

“…LAEF is defined as the force generated by the LA to expel the blood through the mitral valve during atrial systole (5). The contribution of the left atrial contraction to the LV filling becomes more significant, particularly in patients with diastolic dysfunction (6).…”

Left atrial active contractile function parameters assessed by cardiac MR are sensitive to myocardial iron

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“…The myocardial transverse relaxation rate R2* (=1/T2*) assessed by magnetic resonance allows presymptomatic detection and quantification of cardiac iron deposition . Using echocardiography, changes in LA volumes and function have been described as indicators of cardiac dysfunction in systemic iron overload . However, echocardiographic parameters showed low sensitivity to predict myocardial iron .…”