Relationship between slightly elevated NT-proBNP and alterations in diastolic function detected by echocardiography in patients without structural heart disease

An elevated N-terminal pro-brain natriuretic peptide (NT-proBNP) level is associated with the presence of heart failure (HF). However, the significance of slight elevations is unclear in patients without structural cardiopathy. The aim of our study was to measure plasma levels of NT-proBNP in patients without structural cardiopathy, as determined by echocardiography, and establish a relationship with parameters defining diastolic function (DF) by echocardiography. We measured NT-proBNP levels in 82 patients without structural cardiopathy and simultaneously performed Doppler echocardiography. The patients were divided into two groups according to whether their DF was normal (NDF) or abnormal (ADF). Significantly higher levels of NT-proBNP existed in those patients with ADF as compared to patients with NDF (p < 0.01). We found a significant correlation between NT-proBNP levels and early mitral filling velocity (E) divided by the early velocity of the medial mitral valve annulus (Em; p < 0.01; r = 0.31). Globally, the area under the ROC curve (AUC) for the ADF group was 0.94 with an optimal cut off of 55 pg/ml, giving a sensitivity (SE) of 91% and a specificity (SP) of 86%. Cut off points for those over 55 years of age and younger patients were similar (58 pg/ml with a SE of 90% and a SP of 83% versus 55 pg/ml with a SE of 91% and a SP of 86%, respectively), as were those for males (63 pg/ml with a SE of 84% and a SP of 93%) and females (55 pg/ml with a SE of 84% and a SP of 93%). In conclusion, slightly elevated NT-proBNP levels in patients without structural cardiopathy are associated with altered DF parameters, independently of age or gender.