B-type natriuretic peptide and its molecular precursor in myocardial infarction complicated by cardiogenic shock.

BACKGROUND: Plasma measurement of cardiac natriuretic peptides and their biosynthetic precursors is helpful in chronic heart failure patients. In contrast, information on circulating B-type natriuretic peptide (BNP) and its molecular precursor (proBNP) in patients with cardiogenic shock is scarce. We therefore examined proBNP-derived peptides in plasma from patients with myocardial infarction complicated by cardiogenic shock.

METHODS AND RESULTS: Patients were referred for early, invasive therapy because of myocardial infarction complicated by cardiogenic shock (n = 13). Plasma proBNP was measured with an automated assay (NT-proBNP) and an in-house radioimmunoassay (proBNP); BNP concentrations were quantitated with an immunoradiometric assay. The median NT-proBNP concentration was 8.2-fold higher than the corresponding BNP concentration (873 pmol/L [range 41-12,486] versus 107 pmol/L [1-1041], P < .001). Moreover, the NT-proBNP concentration was 3.3-fold higher compared with proBNP (268 pmol/L [19-12,220], P < .01). Despite the molar differences, there was a strong correlation between NT-proBNP and proBNP (r = 0.84, P < .0001) and BNP (r = 0.82, P < .0001) concentrations. Gel filtration chromatography suggested that the proBNP immunoreactivity reflect a molecular form larger than the N-terminal 1-76 fragment.

CONCLUSIONS: The study reveals the plasma profile of proBNP-derived peptides during myocardial infarction complicated by cardiogenic shock. Peripheral concentrations of NT-proBNP, proBNP, and BNP were highly correlated despite marked differences between assays. The results also suggest an increase in cardiac proBNP processing after myocardial infarction and cardiogenic shock.