Serum apelin as a novel non-invasive marker for subclinical cardiopulmonary complications in children and adolescents with sickle cell disease

BackgroundCardiovascular involvement represents a leading cause of mortality and morbidity in sickle cell disease (SCD). Apelin is a peptide involved in the regulation of cardiovascular function.AimTo determine serum apelin among 40 children and adolescents with SCD compared with 40 healthy controls and assess its relation to markers of hemolysis, iron overload as well as cardiopulmonary complications.MethodsSCD patients, in steady state and asymptomatic for heart disease, were studied stressing on hydroxyurea/chelation therapy, hematological profile, serum ferritin and apelin levels. Full echocardiographic study including assessment of biventricular systolic function and pulmonary artery pressure was done.ResultsApelin levels were significantly lower in SCD patients compared with controls (P < 0.001). Cardiopulmonary complications were encountered in 30% of patients. Apelin was significantly decreased among patients with cardiopulmonary disease (P = 0.006) whether those at risk of pulmonary hypertension (P = 0.018) or patients with heart disease (P = 0.043). Hydroxyurea-treated patients had higher apelin levels than untreated ones (P = 0.001). Apelin was negatively correlated to lactate dehydrogenase, indirect bilirubin, serum ferritin, end systolic diameter, tricuspid regurgitant jet velocity, right ventricle systolic pressure, pulmonary vascular resistance and tissue Doppler imaging S wave. Apelin cutoff value of 1650 ng/L could significantly detect the presence of cardiopulmonary complications in SCD with 90.9% sensitivity and 72.4% specificity.ConclusionApelin is a promising marker for screening of SCD patients at risk of cardiopulmonary disease because it is altered during the early subclinical stage of cardiac affection. A combination of apelin and echocardiography provides a reliable method to assess cardiopulmonary affection in young SCD patients.