Left Ventricular Global Longitudinal Strain (LV GLS) Assessed by Echocardiography Predicts Myocardial Fibrosis and Iron Overload in Transfusion Dependent Beta-Thalassemia Patients

Abstract Background Cardiac involvement represents the leading cause of death in transfusion dependent beta-thalassemia (TDT) patients. It is mainly related to cardiac iron overload and myocardial fibrosis, causing progressive damage and a deterioration of systolic and diastolic function. Moreover, myocardial fibrosis may not be directly related with the degree of cardiac iron deposition and it is associated with a higher risk of cardiovascular complications. To date, Cardiac Magnetic Resonance (CMR) is the gold standard for the evaluation of iron overload with T2* sequences and for the detection of myocardial fibrosis with late gadolinium enhancement (LGE). However, CMR is not always feasible. Left Ventricular Global Longitudinal Strain (LV GLS) with Speckle Tracking Echocardiography (STE) is a non-invasive imaging tool, which may play a key role in the early recognition of subclinical myocardial damage and dysfunction (figure 1). Purpose The aim of this study was the evaluation of the role of LV GLS with STE in the characterization of myocardial involvement in a population of TDT patients. Methods An observational, cross-sectional, monocentric study was conducted enrolling 44 patients with TDT from the outpatient clinic of hematology located in our teritary hospital from January 2022 to December 2022. Each patient underwent a thorough clinical evaluation, laboratory testing, transthoracic echocardiogram (TTE) with LV GLS-STE by a trained cardiologist and contrast enhanced CMR with T2* technique and LGE sequences. A T2* value < 20 msec was set to define the presence of iron overload. Results The mean age of patients was 39± 9 years with a slight prevalence of female sex (53% vs 47% respectively). Atherosclerotic cardiovascular risk factors were rarely present, the most common was arterial hypertension in about 12% of patients. The TTE pointed out a left ventricular ejection fraction within the normal range (mean value of 59 ± 5%). As regards LV GLS, the mean value was -21.1 ± 3.0%. Cardiac iron overload was observed in 18% of patients, while about 15% of patients had cardiac fibrosis. A clinical and statistically significant difference was observed between LV GLS values in patients with cardiac iron overload as compared to patients without (-18.2 ± 2.1% vs -20.6 ± 3.1%; p value=0.043). A clinical and statistically significant difference was documented, also, between LV GLS values in patient with cardiac fibrosis as compared to patient without LGE (-16.4 ± 1.7% vs -20.6 ± 2.8%; p value=0.002). As regards cardiac fibrosis, a LV GLS cut-off value of -18,3% was found by the analysis of ROC curve with an AUC of 0.931 (95% CI: 0.846-1.000) (figure 2). Conclusions In a small population of TDT patients we observed that LV GLS with STE may be a promising tool able to help clinicians in the early identification of cardiac iron overload and fibrosis, providing useful information for diagnostic workup and therapeutic approach.