Plasma N-Terminal Pro-Brain Natriuretic Peptide is a sensitive marker of functional severity in hypertrophic cardiomyopathy

Abstract

Objectives: This study sought to determine the diagnostic utility of measurement of plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) in patients with hypertrophic cardiomyopathy (HCM), and the capacity of the method to assess the severity of left ventricular (LV) dysfunction. Background: Plasma BNP is useful in heart failure and HCM. Plasma NT-proBNP has been increasingly used in cardiac diseases but there is no report of NT-proBNP measurement in HCM. Methods: We studied 70 ambulatory patients (mean age 32.6±11.4 years) with HCM (septal thickness >15mm, a non-dilated LV with normal ejection fraction). 15 (21.4%) patients had a resting outflow gradient >30mmHg (obstructive) and 55 did not have (non- obstructive). A control group of 20 normal volunteers age and sex matched were enrolled. The pts were examined by Doppler echocardiography and a blood sample was drawn for NT-proBNP measurement (electrochemiluminescence immunoassay Roche). Comparisons were made between HCM and normals, and between subgroups of HCM. Correlations were verified between levels of NT-proBNP and echocardiographic variables. Results: In the HCM group, the mean plasma NT-proBNP was 1312±1364 pg/ml, versus 41.2±28.3 pg/ml in the control group (p<0.0001). The levels of the peptide were correlated with LA diameter (r=0.39; p=0.001), septal thickness (r=0.24; p=0.04). There was no linear correlation with obstruction but there were differences in the concentrations of NT-proBNP between obstructive (2116±1812 pg/ml) and non-obstructive (1103±1176 pg/ml) HCM groups (p=0.02). Patients with Doppler derived signs of LV filling pressure elevation presented higher levels of NT-proBNP than the others. Conclusions: Measurement of plasma NT-proBNP in HCM pts is a sensitive method for diagnosis and functional evaluation. Further studies are necessary to verify the prognostic value of the test in HCM.