The Role of Exercise Stress Echocardiography for Determination of Subclinical Cardiac Involvement in β-Thalassemia Major

Abstract

β-Thalassemia major (β-TM) patients are at increased risk for cardiovascular diseases. Determination of subclinical cardiac involvement is essential for preventive measures. Thus, we aimed to evaluate the role of stress echocardiography for identification of subclinical cardiac dysfunction in β-TM patients. In this prospective study, 45 β-TM patients who were referred for cardiac evaluation, were enrolled. Exclusion criteria included non sinus rhythm and overt cardiac disease. Stress echocardiography levels and cardiac magnetic resonance imaging (MRI) results were obtained from β-TM patients. Patients were divided into two groups of normal vs. iron overload from cardiac T2* greater or less than 20 msec, respectively. Resting and peak exercise right ventricular stroke volume (RVSV) and left ventricular SV (LVSV) were significantly lower in iron overload vs. normal β-TM patients, respectively (p value <0.05). At peak LV global longitudinal strain (GLS) and myocardial performance index (MPI) were significantly decreased and increased compared with resting in iron overload vs. normal β-TM patients, respectively (p value <0.05). There was a significant relationship between inappropriate hemodynamic response to exercise and lower age (p value = 0.032). Resting LVSV and RVSV seemed better prognosticators for iron overload than LV ejection fraction (LVEF). Decreased GLS and increased MPI at peak exercise could also predict the presence of cardiac iron overload. These measurements by stress echocardiography could be evaluated when cardiac T2* could not be determined.