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). conclusions: 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.