Predictive value of B-type natriuretic peptides in detecting latent left ventricular diastolic dysfunction in beta-thalassemia major.
BACKGROUND
Beta-thalassemia major is a unique disease characterized by early diastolic dysfunction, related exclusively to iron myocardial deposition. N-terminal-proBNP(amino-terminal) (NT-proBNP) and B-type natriuretic peptide (BNP) are sensitive biomarkers for the detection of asymptomatic left ventricular (LV) dysfunction, and they have important diagnostic and prognostic implications. Using beta-thalassemia as a model disease with isolated diastolic dysfunction, we sought to investigate the predictive value of NT-proBNP and BNP levels in comparison with the conventional and new Doppler echocardiography indexes in detecting this disorder.


METHODS
Seventy beta-thalassemia major patients (mean age 27.2 +/- 12.5 years) with normal LV systolic function (mean LV ejection fraction = 59% +/- 6.8%), and 50 healthy age-matched adults (control group: mean age 25.5 +/- 10.1 years, mean LV ejection fraction = 60% +/- 4.5%) were included. All subjects were studied thoroughly by tissue Doppler echocardiography and blood samples were taken for plasma NT-proBNP and BNP measurements at the same time. To examine LV diastolic function, patients were divided in 3 groups according to the E mitral/E mitral annulus ratio (E/E'): group A, patients without diastolic dysfunction: E/E' ratio <8; group B, patients with suspected diastolic dysfunction: E/E' ratio 8 to 15; group C, patients with documented diastolic dysfunction: E/E' ratio, >15.


RESULTS
NT-proBNP and BNP levels were higher in thalassemic patients compared with the control group (NT-proBNP levels: 80 +/- 19 vs 21 +/- 4 pg/mL, P < .001; BNP levels: 34 +/- 6 vs 9 +/- 3 pg/mL, P < .001). NT-proBNP levels showed a statistically significant increase in group C in comparison to groups A and B, which was also detected between groups A and B (A vs B: P < .05). BNP levels were also significantly increased in group C in comparison to the other 2 groups, but there was no statistically significant difference between groups A and B. Using receiver operating characteristic analysis, NT-proBNP at a cut point of 49.2 pg/mL was highly accurate (area under curve: 0.97, P < .001) in ruling out diastolic dysfunction (E/E' <8) with a sensitivity of 93.7% and a specificity of 89.6%.


CONCLUSIONS
BNP and NT-proBNP levels are significantly increased in documented left ventricular diastolic dysfunction, while NT-proBNP seems to have better predictive value in detecting latent left ventricular diastolic dysfunction in beta-thalassemia major.
Kremastinos
Dimitrios Th
DT
2nd University Department of Cardiology, Attikon General Hospital, Athens, Greece.
Hamodraka
Eftihia
E
Parissis
John
J
Tsiapras
Dimitrios
D
Dima
Kleanthi
K
Maisel
Alan
A
D000293:Adolescent; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D015150:Echocardiography, Doppler; D005260:Female; D054144:Heart Failure, Diastolic / Q000097:blood / Q000150:complications / Q000000981:diagnostic imaging; D006801:Humans; D016014:Linear Models; D008297:Male; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D015588:Observer Variation; D010446:Peptide Fragments / Q000097:blood*; D011237:Predictive Value of Tests; D011336:Probability; D011379:Prognosis; D012372:ROC Curve; D012016:Reference Values; D018570:Risk Assessment; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D018487:Ventricular Dysfunction, Left / Q000097:blood* / Q000150:complications / Q000000981:diagnostic imaging*; D055815:Young Adult; D017086:beta-Thalassemia / Q000097:blood* / Q000150:complications / Q000175:diagnosis
D015415:Biomarkers; D010446:Peptide Fragments; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain