Endothelial function and arterial stiffness in sickle-thalassemia patients

Abstract

Background Homozygous sickle-cell anemia and β-thalassemia are characterized by impaired endothelial function, while data on arterial stiffness have hitherto been conflicting. We sought to investigate aortic elastic properties and endothelial function in sickle-thalassemia, which combines molecular and clinical features of the above conditions. Methods and results Forty-seven sickle-thalassemia patients, younger than 45 years, with preserved left ventricular (LV) function and no history of smoking, systemic or pulmonary hypertension, diabetes mellitus, dyslipidemia or thyroid disease, along with 40 healthy controls were studied. Aortic strain, distensibility and stiffness index were calculated by echocardiographically-obtained aortic root diameters. Brachial artery endothelial function was assessed by ultrasonographic evaluation of flow-mediated dilatation (FMD) and nitrate-mediated dilatation (NMD). Left ventricle was assessed by echocardiography. Patients had an impaired FMD (4.2 ± 2.9% versus 9.2 ± 3.8% in controls, p < 0.001) with a preserved NMD (16.9 ± 5.6% versus 15.2 ± 4.8% in controls, p > 0.05). Aortic strain and distensibility were lower and aortic stiffness index was higher in patients compared to controls (8.1 ± 4.6 versus 5.8 ± 2.9, p < 0.01). Indexed LV diameters and mass were higher in patients. Systolic LV function was preserved, while 14.9% of patients had an impaired relaxation transmitral inflow pattern. Patients’ LV mass index and diastolic mitral E wave deceleration time were positively correlated with aortic stiffness index ( p < 0.001). Conclusion Sickle-thalassemia is characterized by a complex vasculopathy, consisting of endothelial dysfunction and increased arterial stiffness, with a global effect on cardiovascular function.