Biomarker Responses during and after Treatment with Nesiritide Infusion in Patients with Decompensated Chronic Heart Failure

Abstract

Objective methods to assess the adequacy of medication therapy for patients with advanced heart failure are lacking. Serial measurements of biomarkers might be beneficial. Therapy guided by N-terminal pro-B-type natriuretic peptide (NT-proBNP) might be helpful because NT-proBNP should be lowered by therapies that decrease endogenous BNP secretion. NT-proBNP and BNP were measured in a nonconsecutive patient cohort receiving clinically indicated intravenous nesiritide. Blood samples were drawn before, at 6 and 24 h during, and at 6 h after infusion. A reduction in NT-proBNP was defined as a decrease from baseline during infusion ("infusion responders") of >3 SD of the variability of the assay measurement (approximately 20%). Patients with decreases >20% in both NT-pro BNP and BNP at 6 h post infusion were designated "biochemical responders". Forty patients [27 males; mean (SE) age, 68 (2) years; mean (SE) left ventricular ejection fraction, 25 (1.4)%] were studied. All patients improved clinically. Overall, the changes in NT-proBNP were a 18 (4.6)% [mean (SE)] and 19.8% (median) decrease from baseline at 24 h of infusion and a 22 (6.0)% and 17.8% decrease at 6 h post infusion (P <0.001 compared with baseline). In a large number of patients, decreases in NT-proBNP were, however, within the variability of the assay. Subgroup analysis showed that 22 of 40 patients were infusion responders with a >20% decrease from baseline in NT-proBNP during nesiritide infusion, whereas only 12 patients were biochemical responders with >20% decreases from baseline postinfusion for both NT-proBNP and BNP. In this study, many patients had decreased NT-proBNP and BNP values after therapy with nesiritide, but the majority of patients did not demonstrate biochemically significant decreases in analytes despite a clinical response. Until we know more about the responses of natriuretic peptides to therapies such as nesiritide, a strategy of monitoring NT-proBNP and BNP to guide therapy cannot be universally advocated.