Updated project metadata. Myocardial tissue samples were explanted from the explanted left ventricle of heart failure patients with DCM (n=4), left ventricular infarct, peri-, and non-infarct regions of HF patients with ICM (n=4) at the time of their heart transplant surgeries, and the left ventricle of age- and sex-matched non-failing controls (NFC, n=4). Comparative quantitative analysis was performed on three independent sets (DCM vs. NFC, infarct vs. non-infarct, and peri- vs. non-infarct) labeled with 10-plex tandem mass tags. Following enrichment of phosphorylated peptides, the flow-through and eluted fractions were collected separately and subjected to LC-MS/MS (liquid chromatography-tandem mass spectrometry) on a Q-Exactive HF for global proteomics and phosphoproteomics profiling respectively.