Evaluating the Correlation between Serum NT-proBNP Level and Diastolic Dysfunction Severity in Beta-Thalassemia Major Patients

Background: N-terminal pro-brain natriuretic peptide (NT-proBNP) is a sensitive biomarker for the detection of asymptomatic left ventricular (LV) dysfunction. Since β-thalassemia major patients suffer from early diastolic dysfunction due to iron deposition of chronic blood transfusion, we tried to evaluate the correlation between the serum NT-proBNP level and the severity of LV diastolic dysfunction determined by echocardiography in these patients. Methods: Fifty β-thalassemia major patients with normal LV systolic function were studied by tissue Doppler echocardiography, and blood samples were taken at the same time to measure the serum NT-proBNP level. Using flow velocity through the mitral valve on the tissue velocity of the mitral annulus in early ventricular filling (E/E') as an LV diastolic function indicator, the patients were divided into 3 groups: group 1) no diastolic dysfunction (E/E' < 8), group 2) suspected diastolic dysfunction (E/E' = 8-15), and group 3) documented diastolic dysfunction (E/E' >15). Other variables assessed included sex, age, method of chelator therapy, and mean hemoglobin and ferritin levels for the past 2 years. Results: According to the echocardiographic findings of all the 50 patients (29 male and 21 female) with an age range of 11-35 years (mean = 17.98 y), 46% were classified in group 1, 54% in group 2, and none in group 3. The NT-proBNP level was 1070 ± 566 ng/mL in group 1 and 974 ± 515 ng/mL in group 2. The t-test showed no significant difference between groups 1 and 2 in the NT-proBNP level (p value = 0.536). Conclusion: Due to specific conditions in thalassemia major patients, the correlation between the serum NT-proBNP level and the severity of diastolic dysfunction seems to be not meaningful.