Pulmonary hypertension in patients with sickle cell/beta thalassemia: incidence and correlation with serum N-terminal pro-brain natriuretic peptide concentrations.

BACKGROUND AND OBJECTIVES

Pulmonary hypertension (PH) is increasingly observed in sickle cell disease (SCD) and beta-thalassemia (beta-thal), but there is no information on its prevalence in patients with HbS/beta-thal. The amino-terminal fragment of B-type natriuretic peptide (NT-proBNP) is considered as an independent prognostic factor in PH. The aim of this study was to evaluate the incidence of PH and its correlation with clinical and laboratory findings, including NT-proBNP, in patients with HbS/beta-thal.

DESIGN AND METHODS

We studied 84 HbS/beta-thal patients; 51% had been receiving hydroxyurea for a median time of 9 years. The presence of PH was evaluated using Doppler echocardiography and NT-proBNP serum levels were determined by an electrochemiluminescence immunoassay.

RESULTS

The incidence of PH in our cohort of HbS/beta-thal patients was 33%. PH patients had elevated values of NT-proBNP, reticulocyte counts and serum ferritin compared with patients without PH. However, even patients without PH had elevated concentrations of NT-proBNP compared with controls. An NT-proBNP level of 153.6 pg/mL had the highest sensitivity (85.7%) and specificity (94.6%) for detecting PH in our patients. NT-proBNP levels correlated with measures of pulmonary artery systolic pressure (tricuspid regurgitant jet velocity and right ventricular systolic pressure), left atrial area and diastolic dysfunction. The administration of hydroxyurea did not affect the presence of PH.

INTERPRETATION AND CONCLUSIONS

The incidence of PH in patients with HbS/beta-thal is similar to that observed in patients with SCD. Serum NT-proBNP is a strong indicator of PH in HbS/beta-thal. The correlation between PH and reticulocyte counts and ferritin suggests that the degree of hemolysis and iron overload is implicated in the pathogenesis of PH in HbS/beta-thal.