Plasma Brain Natriuretic Peptide as an Indicator of Left Ventricular Systolic Function and Long-term Survival After Acute Myocardial Infarction

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Abstract
Background Elevated plasma levels of atrial natriuretic peptide (ANP) and the N-terminal fragment of the ANP prohormone (N-ANP) are associated with decreased left ventricular function and decreased long-term survival after acute myocardial infarction (AMI). Previous data suggest that plasma brain natriuretic peptide (BNP) may increase proportionally more than plasma ANP after AMI and in chronic heart failure. The diagnostic and prognostic value of plasma BNP as an indicator of left ventricular dysfunction and long-term survival after AMI, relative to that of ANP and N-ANP, remain to be established. Methods and Results Venous blood samples for analysis of ANP, N-ANP, and BNP were obtained on day 3 after symptom onset from 131 patients with documented AMI. Left ventricular ejection fraction was determined by echocardiography in a subsample of 79 patients. Twenty-eight cardiovascular and 3 noncardiovascular deaths occurred during the follow-up period (median, 1293 days). All three peptides proved to be powerful predictors of cardiovascular mortality by univariate Cox proportional hazards regression analyses (ANP: P <.0001; N-ANP: P =.0002; BNP: P <.0001). In a multivariate model, plasma BNP ( P =.021) but not ANP ( P =.638) or N-ANP ( P =.782) provided additional prognostic information beyond left ventricular ejection fraction. Logistic regression analysis showed that ANP ( P =.003) and N-ANP ( P =.027) but not BNP ( P =.14) were significantly associated with a left ventricular ejection fraction ≤45%. Conclusions These results suggest that plasma BNP determination provides important, independent prognostic information after AMI. Although plasma ANP appears to be a better predictor of left ventricular dysfunction, plasma BNP may have greater potential to complement standard prognostic indicators used in risk stratification after AMI because of its strong, independent association with long-term survival, enhanced in vitro stability, and simplicity of analysis.