Pathophysiological processes and novel biomarkers associated with congestion in heart failure

Background: Congestion is the main driver behind symptoms of heart failure (HF), but pathophysiology related to congestion remains poorly understood.Objectives: Using pathway and differential expression analyses, the authors aim to identify biological processes and biomarkers associated with congestion in HF.Methods: A congestion score (sum of jugular venous pressure, orthopnea, and peripheral edema) was calculated in 1,245 BIOSTAT-CHF patients with acute or worsening HF. Patients with a score ranking in the bottom or top categories of congestion were deemed noncongested (n = 408) and severely congested (n = 142), respectively. Plasma concentrations of 363 unique proteins (Olink Proteomics Multiplex CVD-II, CVD-III, Immune Response and Oncology II panels) were compared between noncongested and severely congested patients. Results were validated in an independent validation cohort of 1,342 HF patients (436 noncongested and 232 severely congested).Results: Differential protein expression analysis showed 107/363 up-regulated and 6/363 down-regulated proteins in patients with congestion compared with those without. FGF-23, FGF-21, CA-125, soluble ST2, GDF-15, FABP4, IL-6, and BNP were the strongest up-regulated proteins (fold change [FC] >1.30, false discovery rate [FDR], P < 0.05). KITLG, EGF, and PON3 were the strongest down-regulated proteins (FC <−1.30, FDR P < 0.05). Pathways most prominently involved in congestion were related to inflammation, endothelial activation, and response to mechanical stimulus. The validation cohort yielded similar findings.Conclusions: Severe congestion in HF is mainly associated with inflammation, endothelial activation, and mechanical stress. Whether these pathways play a causal role in the onset or progression of congestion remains to be established. The identified biomarkers may become useful for diagnosing and monitoring congestion status.