This research aimed to identify protein biomarkers of right ventricular dysfunction in patients with advanced heart failure with reduced ejection fraction (HFrEF). Samples of myocardium from both, right and left ventricles (RV, LV) were obtained from 10 HFrEF patients with right ventricular dysfunction (RVD), 10 HFrEF patients without RVD (noRVD) undergoing heart transplantation, and 10 non-failing unused donor hearts (Control). Tissue samples were homogenized and extracted using mild Triton X-100 detergent and processed by SP3 extraction to remove the detergent prior the analysis, (LFQ) proteomic analysis identified a total of 4 032 proteins in the left ventricle and 3 788 proteins in the right ventricle.