Correlation Between Levels of N-terminal Pro-B-Type Natriuretic Peptide and Degrees of Heart Failure

BACKGROUND: The N-terminal fragment of pro Brain Natriuretic Peptide (NT-pro BNP) is a neuro-hormone synthesized in the cardiac ventricles in response to increased wall tension. The purpose of this study was to assess the correlation between the NT-pro BNP levels and the New York Heart Association function class (NYHA Fc) of dyspnea and echocardiographic findings for the patients who visited our cardiology departments. METHODS: From October, 2002 to April, 2003, serum NT-pro BNP levels were measured in 348 patients who visited the Samsung Medical Center and the Jong Koo Lee Heart Clinic. RESULTS: The NT-pro BNP levels were increased with the progression of NYHA Fc of dyspnea (p<0.001 by ANOVA), the increase in the systolic left ventricular internal dimension (p<0.05), and the decrease in the ejection fraction (p<0.01). For the NYHA Fc I patients, the NT-pro BNP levels were positively correlated with age (p<0.001) and left atrial size (p<0.001). For the patients with ischemic heart disease, the NT-pro BNP levels were also positively correlated with the NYHA Fc (p<0.001 by ANOVA). The NT-pro BNP levels were increased with the increase in the systolic (p<0.001) and diastolic pressure (p=0.017), the left ventricular internal dimension as well as the decrease in the ejection fraction (p<0.001). The area under the receiver operating characteristic (ROC) curve for the NT-pro BNP levels was 0.994 (95% confidence interval, 0.979-0.999), and the most reliable cut-off level for the NT-pro BNP was 293.6 pg/mL. CONCLUSION: The NT-pro BNP levels were positively correlated with the NYHA Fc of dyspnea and the systolic dysfunction for the patients who visited our cardiology departments. A 300 pg/mL value for the NT-pro BNP cut-off point appears to be a sensitive level to differentiate dyspnea originating from an ailing heart or not for the patients who visited our cardiology departments.