Exercise Stress Echocardiography with Tissue Doppler Imaging (TDI) Detects Early Systolic Dysfunction in Beta-Thalassemia Major Patients without Cardiac Iron Overload

OBJECTIVES: To evaluate left and right myocardial performance at rest and after maximal exercise by conventional and Tissue Doppler Imaging (TDI) echocardiography. BACKGROUND: Iron Overload Cardiomyopathy (IOC) is the main cause of death in thalassemia major (TM) patients but conventional Echocardiography fails to predict early cardiac dysfunction. As TDI is able to demonstrate regional myocardial dysfunction and stress test may reveal abnormalities which are not evident at rest, we wondered if echocardiographic parameters may reveal abnormalities when applied first at rest and then after a physical effort. METHODS: We enrolled 46 consecutive beta-TM patients and 39 control subjects without evidence of cardiac disease; two echocardiograms, at baseline and at the end of maximal exercise on supine bicycle ergometer, were done. All TM patients had a liver iron assessment by SQUID (Superconducting Quantum Interference Device) and a cardiac iron one by MRI (T2*) evaluation. RESULTS: 38 TM patients had no evidence of cardiac iron overload. Whereas TM patients did not shown diastolic dysfunction and all of them presented a good global response to exercise, TDI detected a reduced increase of the S’ waves of left ventricle basal segment during exercise. This finding seems to have some weak but interesting relations with iron overload markers. Pulmonary artery systolic pressure (PAPs) values were greater than in control subjects both at rest and after exercise CONCLUSIONS: in our study, exercise stress TDI-echocardiography was able to demonstrate subtle systolic abnormalities that were missed by Conventional Echocardiography. Further studies are required to determine the meaning and the clinical impact of these results.