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N-terminal fragment of proBNP is a marker of high cardiac output cardiomyopathy evaluated by CMR in thalassemia syndromes
© Meloni et al; licensee BioMed Central Ltd. 2010
Published: 21 January 2010
In thalassemia patients heart failure remains the main cause of mortality. High cardiac output state due to chronic anaemia is a significant determinant of cardiomyopathy, in particular in thalassemia intermedia (TI) patients (a moderate form, not transfusion dependent). Hypoxia and volume overload are known stimuli for plasma N-terminal fragment of proBNP (NT-proBNP) raise. Nevertheless, NT-proBNP role in clinical management of thalassemia patients has not been fully investigated.
Aim of our study was to assess the role of NT-proBNP assay in a large prospective cohort of thalassemia patients, evaluated by cardiovascular magnetic resonance (CMR).
215 thalassemia patients (39 TI, age 38 ± 12 years, 51% females) and 176 thalassemia major patients (TM, age 30 ± 9 years, 54% females) underwent consecutively CMR (1.5 T) and blood sampling for plasma assay of NT-proBNP. Myocardial iron overload was assessed using a multislice multiecho T2* approach able to provide the global T2* value in the left ventricle. Cine sequences were obtained to quantify biventricular morphological and functional parameters. RV and LV volumes and ejection fraction (EF) were evaluated by a semi-automatic software (Mass Plus, Leiden, NL).
NT-proBNP levels were comparable in TI and TM patients (139 ± 146 ng/L versus 108 ± 122 ng/L; P = NS). Mean haemoglobin levels (P < 0.0001) and myocardial iron overload (P = 0.001) were significantly lower in TI than in TM patients. Left end-diastolic volume (P < 0.0001) and mass indexes (P = 0.002), right ejection fraction (P < 0.0001) and biatrial area indexes (P = 0.006) were significantly higher in TI vs. TM patients. In TI patients NT-proBNP was negatively associated with mean haemoglobin levels (r = -0.6, P = 0.008) and positively with left and right atrial area indexes (r = 0.6, P = 0.001 and r = 0.4, P = 0.007, respectively), left and right end diastolic volume indexes (r = 0.5, P = 0.003 and r = 0.3, P = 0.04, respectively) and left ventricular mass index (r = 0.4, P = 0.007). In TM patients no significant correlation was found between NT-proBNP levels and morphological biventricular parameters. In both groups no significant correlation was found between NT-proBNP levels and myocardial iron overload.
Hypoxia and volume overload due to chronic anaemia, more pronounced in TI patients, justify the correlation between NT-proBNP and high cardiac output-related findings in TI patients. These data suggest a) a potential routinary use of NT-proBNP as marker of high cardiac output cardiomyopathy in the anaemic thalassemia population; b) to reconsider the current haematological/transfusional management in TI patients.
This article is published under license to BioMed Central Ltd.