N-terminal proBNP levels in patients with Chagas disease: A marker of systolic and diastolic dysfunction of the left ventricle

Abstract

NT-proBNP levels are known to be elevated in systolic and diastolic dysfunction. Doppler indices of diastolic dysfunction (DD) have been shown to have prognostic value in patients with Chagas' cardiomyopathy (CC). However, the additional value of NT-proBNP levels in further stratifying these patients according to DD has not been established. This study analyzed the correlation of N-terminal proBNP (NT-proBNP) levels with systolic and diastolic function in patients with CC. NT-proBNP levels were measured in 59 patients with dilated cardiomyopathy due to Chagas disease without other systemic illness that were studied by Doppler echocardiography, including left atrial volume (LAV) calculation and tissue Doppler evaluation of LV longitudinal function. Univariate analysis showed a strong correlation of NT-proBNP values with LVEF (r=-0.733, p<0.001) and a weak correlation with most Doppler echocardiographic parameters of diastolic function. On a multivariate analysis, LVEF and LAV volume emerged as correlating with elevated levels of the NT-proBNP. Patients with restrictive filling pattern (n=10), when compared to other patterns of DD, (n=49), showed a lower LVEF (25.4+/-6.4% vs. 39.8+/-9.4, p<0.001), a larger LAV (50.1+/-17.2 vs. 37.7+/-15.6 ml/m(2), p=0.004) and higher NT-proBNP levels (median+/-IQR: 3488+/-3056 vs. 492+/-700 pg/dl, p<0.001). A marked elevated concentration of NT-proBNP (> or =800 pg/ml) had a sensitivity of 90.0%, specificity of 70.5%, positive predictive value of 40.9% and negative predictive value of 96.9% for detecting a restrictive filling pattern. In patients with CC, NT-proBNP augmentation is a marker of LV dysfunction, with higher levels correlating with the more severe forms of both systolic and diastolic dysfunction.