Atrial Fibrillation (AFib) is associated with increased plasma natriuretic peptide (MR-proANP, BNP and NT-proBNP) levels in the absence of heart failure (HF), according to a new study published in JACC: Heart Failure.

The study, which looked at 1,445 emergency department patients with acute dyspnea enrolled in the BACH (Biomarkers in ACute Heart Failure) Trial, found that plasma concentrations of all three peptides were lowest in patients without AFib or HF. Plasma concentrations of the three peptides were significantly higher in patients with AFib and without heart failure (p <0.001 for all three peptides), and were further elevated in HF patients with or without AFib (p <0.001 for all three peptides).

The study demonstrated that in the absence of AFib, all three natriuretic peptides showed strong discrimination of HF, but in the presence of AFib, all three had substantially lower areas under receiver operator characteristic curves (AUCs), resulting in clear reductions in the diagnostic power of MR-proANP, BNP, and NT-proBNP.

According to the study authors, the findings "indicate the need to consider different (i.e., higher) diagnostic threshold values for natriuretic peptides in the presence of AFib." In addition, the authors urge a continued search for markers that reflect the presence of HF without confounding by AFib.

In an editorial comment, James L. Januzzi, JR, MD, FACC, and G. Michael Felker, MD, FACC, note that the results of this study "have important implications for both the clinical interpretation of biomarker data in patients with acute HF, as well as for design of clinical trials using natriuretic peptide measurements as inclusion criteria."

Moving forward, Januzzi and Felker add that any new candidate for a novel biomarker of HF "should primarily reflect important pathways involved in the pathophysiology of HF and should not recapitulate clinical information already available at the bedside, including that gained from measurement of gold standard biomarkers such as the natriuretic peptides."

This study was one of three papers published in JACC: Heart Failure addressing biomarkers in HF. A second study  described for the first time net cardiac secretion of proBNP1-108 in subjects with nonfailing and failing hearts, and found a greater transcardiac gradient in HF; while a third study  introduced a novel percutaneously implanted ventricular assist device-based protocol with the potential to "reverse"-model the pathophysiology of cardiogenic shock.

Keywords: Shock, Cardiogenic, Biomarkers, Heart-Assist Devices, Heart Failure, Atrial Fibrillation, ROC Curve, Dyspnea, Natriuretic Peptide, Brain