Added value of speckle tracking in the evaluation of cardiac function in patients with sickle cell disease

Speckle tracking echocardiography is a new means of evaluating cardiac function. The principle of speckle tracking is to measure myocardial strain, based on local shortening, lengthening and thickening of the muscles. It has been proposed that the left ventricle global longitudinal strain (LV-GLS) could be a useful tool for the detection of early systolic dysfunction in patients under cardiotoxic chemotherapy (Thavendiranathan et al, 2014). Moreover, the high reproducibility of the LV-GLS represents an advantage over the left ventricle ejection fraction (LVEF) (King et al, 2016; Medvedofsky et al, 2017). Compared to the LVEF, the LV-GLS is less affected by changes in loading conditions, which makes it a potentially useful tool in patients with sickle cell disease (SCD), due to the chronic overload associated with SCD. However, in this population, studies are rare and results are conflicting (Ahmad et al, 2012; Sengupta et al, 2012; Barbosa et al, 2014; Hammoudi et al, 2014). The primary aim of our study was to determine whether the LV-GLS was abnormal in a monocentric population of adults with SCD, compared to a matched population of healthy individuals. The secondary aim was to investigate correlations between the echocardiographic parameters and the biological and clinical evaluations of patients with SCD. The institutional Ethics Committee approved the protocol. All patients provided informed consent. We prospectively included 37 patients with SCD and 34 healthy, ageand sex-matched controls. The patient and control groups were similar in age (31 10 years vs. 32 10 years, respectively). The LVEF was significantly lower in the SCD group than in the control group (Teicholz: 61 8% vs. 67 6%; P = 0 05; Simpson: 61 9% vs. 69 3%; P < 0 05; Table I). However, only one patient had a Simpson LVEF < 50%. The left ventricular (LV) mass and LV end diastolic diameter (LVEDD) were higher in the patient group (LV mass: 107 g/m vs. 70 g/m, P < 0 05 and LVEDD: 53 mm vs. 46 mm; P < 0 05). The myocardial performance index was higher (higher values indicate impaired LV function) in the patient group compared to the control group (0 38 vs. 0 27; P < 0 05). The LV-GLS was significantly lower in the SCD group than in the control group ( 19 4% vs. 22 4%; P < 0 05), and it was abnormal (strain > 18%) in 8 (21%) patients of the SCD group. Diastolic function was abnormal in three SCD patients (8%), but normal in the entire control group. The tricuspid regurgitation velocity was higher in the SCD group than in the control group (2 24 m/s vs. 1 96 m/s, P < 0 05). However, no patient had pulmonary hypertension. The multivariate analysis results (Table II) showed that only the LV-GLS and LVEDD remained significantly different between groups. Among patients with SCD, the mean Hb was 94 g/l (range: 61–122 g/l) and the mean HbF was 12 7% (range: 1– 28 6%). The mean ferritin level was 644 lg/l (range: 13– 7267 lg/l). Iron overload, defined as a ferritin level greater than 1000 lg/l, was observed in five patients. The mean Nterminal pro b-type natriuretic peptide (NTproBNP) level was 154 pg/ml (range 12–1685 pg/ml). The mean patient walking distance was 66% of the predicted value (range: 33–88%).