Proteomic patterns according to ejection fraction: an EMPEROR-programme analysis

Left ventricular ejection fraction (LVEF) has been incorporated as an inclusion criterion in HF trials. Patient's characteristics, event risk, and treatment response vary according to LVEF. A better understanding of the biological processes across LVEF is warranted. To study proteomic biomarker expression across LVEF using data from the EMPEROR-Programme.

Two thousand two hundred and fifty-four patients who had proteomic measurements available using 1134 proteins overlapping between the Explore 1536 and 3072 Olink® platforms were included. Main analyses were performed within the EMPEROR-Preserved dataset due to differences in entry criteria between EMPEROR-Preserved and EMPEROR-Reduced with higher entry N-terminal pro B-type natriuretic peptide (NT-proBNP) levels that varied by LVEF cut-offs in the latter. Protein concentrations were compared using ordinal logistic regression across LVEF categories: 41%-49%, 50%-59%, and ≥60%. The resulting β-coefficient indicates the change in the log-odds for the outcome of being in a lower LVEF category for every NPX unit in log2 scale. Analyses were adjusted for covariates and a false-discovery-rate (FDR) correction was applied.

A total of 297 proteins exhibited a trend of expression across LVEF categories in EMPEROR-Preserved after adjustment for potential confounders and correction for test multiplicity. Of these, the top 10 proteins were: NT-pro BNP (β = 0.18, 95% CI 0.09-0.27), Wnt inhibitory factor-1 (β = 0.40, 95% CI 0.19-0.61), sialomucin core protein 24 (β = 0.48, 95% CI 0.22-0.74), phospholipid transfer protein (β = 0.38, 95% CI 0.17-0.59), natriuretic peptides B (β = 0.13, 95% CI 0.06-0.20), intercellular adhesion molecule 5 (β = 0.31, 95% CI 0.14-0.49), neural cell adhesion molecule 2 (β = 0.45, 95% CI 0.19-0.70), neural cell adhesion molecule L1-like protein (β = 0.45, 95% CI 0.19-0.71), interactor protein for cytohesin exchange factors 1 (β = 0.12, 95% CI 0.05-0.19), and 3-ketoacyl-CoA thiolase, peroxisomal (β = 0.17, 95% CI 0.07-0.26). The correlation between these proteins and LVEF was generally weak (Rho ≤0.2).

Within EMPEROR-Preserved, the top differentially expressed circulating proteins suggest that pathways related to natriuretic peptides, cell-adhesion, and clonal haematopoiesis are overexpressed at mildly-reduced ejection fraction, but none of the proteins passed the 5%FDR cut-off, and the correlation between circulating proteins and LVEF was weak. These findings suggest that circulating proteins may not be a good discriminant of ejection fraction.