/Myocardial samples of LV and RV from 10 patients with HFrEF and severe RVD, 10 patients with HFrEF and preserved RV function (noRVD), and 10 control individuals were subjected to quantitative proteomic analysis. Supervised discrimination analysis (sparse partial least squares discrimination analysis), of the proteomic data from RV and LV clearly separated nonfailing (control) hearts from the failing hearts and, albeit less completely, also samples from patients with RVD (red) and patients without RVD (green) in both ventricles (Figure 1). This incomplete separation of RVD and noRVD proteomic profiles reflects rather mild changes in the myocardial proteome of patients with HFrEF with RVD and without RVD. In fact, we identified only 12 and 6 differentially expressed proteins (>2-fold; P<0.05) in the RV and LV of patients with RVD, respectively, compared with patients without RVD (Figure 2). None of the 18 RVD-associated changes in protein expression was identified simultaneously in both ventricles.