Plasma N-BNP measured 2 to 4 days after myocardial infarction independently predicted left ventricular function and 2-year survival. Stratification of patients into low- and high-risk groups can be facilitated by plasma N-BNP or BNP measurements, and one of these could reasonably be included in the routine clinical workup of patients after myocardial infarction.

Abstract-Cardiac natriuretic peptides, especially amino terminal pro-Brain Natriuretic Peptide (NT-proBNP), are emerging as powerful circulating markers of cardiac function. However, the in vivo secretion and elimination (t 1 ⁄2) of these peptides during acute volume overload have not been studied. We present the first report of the secretion and elimination of cardiac natriuretic peptides, based on deconvolution analysis of endogenous ovine plasma levels measured by specific radioimmunoassay. Four normal, conscious sheep underwent rapid right ventricular pacing (225 bpm) for 1 hour to stimulate acute cardiac natriuretic peptide release. Plasma samples and right atrial pressure measurements were taken at regular intervals 30 minutes before, during, and 4 hours after pacing. Baseline right atrial pressure significantly increased (Pϭ0.02) during the 1 hour of pacing in association with a prompt increase in plasma BNP (Pϭ0.03), atrial natriuretic peptide (Pϭ0.01), and NT-proBNP (Pϭ0.02). Deconvolution analysis showed that the t 1 ⁄2 of NT-proBNP (69.6Ϯ10.8 minutes) was 15-fold longer than BNP (4.8Ϯ1.0 minutes). Despite sustained increases in atrial pressure, cardiac secretion of natriuretic peptides (particularly atrial natriuretic peptide) fell during the pacing period, suggesting a finite source of peptide for secretion. Size-exclusion high-performance liquid chromatography revealed NT-proBNP to be a single immunoreactive peak, whereas BNP comprised at least 2 immunoreactive forms. These findings, especially the prompt secretion of BNP and the prolonged t 1 ⁄2 of NT-proBNP, clarify the metabolism of BNP forms and help to explain the diagnostic value of NT-proBNP measurement as a sensitive marker of ventricular function. Key Words: heart failure Ⅲ natriuretic peptides Ⅲ myocytes Ⅲ metabolism I ncreases in circulating volume and cardiac filling pressures promote increased secretion of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) from mammalian cardiac myocytes. ANP is synthesized and stored in the atria, whereas BNP is released from the ventricle. 1,2 ProANP is the dominant storage form in mammalian cardiac extracts 3 and is cleaved during secretion into 2 fragments, ANP [4][5][6] In contrast, myocytes contain either proBNP alone or a complex ratio of proBNP, BNP,3 suggesting that the mechanism responsible for cardiac processing of proBNP differs from that of proANP. Circulating ANP is rapidly cleared by specific clearance receptor (NPR-C) and enzymatic (neutral endopeptidase, NEP) pathways 10 -12 in contrast to 8,9,13 which is slowly metabolized and accumulates in plasma at concentrations 10-to 50-fold those of ANP. 13 Whereas BNP is cleared from the circulation by NPR-C and NEP at variable rates across species, 1,14 the absolute and proportional increment of NTproBNP in clinical and experimental heart failure 15-18 exceeds that of BNP.The growing recognition of the value of plasma levels of BNP and NT-proBNP as markers of left ventricular function 17 and prognosis after myocardial infarcti...

Background-Plasma neurohormones were analyzed for prediction of adverse outcomes and response to treatment in 415 patients with ischemic left ventricular dysfunction randomly assigned to receive carvedilol or placebo. Methods and Results-Atrial natriuretic peptide, brain natriuretic peptide (BNP), or norepinephrine (NE) levels above the group median were associated with increased mortality rates and heart failure. On multivariate analysis, both BNP and NE interacted with treatment to predict death or heart failure independent of age, New York Heart Association class, and left ventricular ejection fraction. For placebo, supramedian levels of BNP were associated with 3-fold the mortality rate of inframedian levels (20/104; 19% vs 6/99; 6%; PϽ0.01). For carvedilol, mortality rate was comparable in these 2 subgroups (12/109; 11% vs 8/94; 9%; NS). Corresponding rates for heart failure were 29/104 (28%) versus 3/99 (3%; PϽ0.001) for placebo and 16/109 (15%) versus 7/94 (7%; NS) for carvedilol. High NE levels did not predict additional benefit from carvedilol, which significantly reduced heart failure admissions only in those with NE levels below the median (13.1% to 4.0%; PϽ0.01). In the 23% of the study population with supramedian BNP but inframedian levels of NE, carvedilol reduced hospital admission with heart failure by Ͼ90% (PϽ0.001). Conclusions-Carvedilol reduced mortality rates and heart failure in those with higher pretreatment BNP levels but lesser activation of plasma NE. Neurohumoral profiling may guide introduction of ␤-blockade in heart failure. (Circulation. 1999;99:786-792.)

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