Quantitative Proteomics of Changes in Energy Metabolism-Related Proteins in Atrial Tissue From Valvular Disease Patients With Permanent Atrial Fibrillation

Background: The modification of cardiac energy metabolism during atrial fibrillation (AF) has been demonstrated in previous studies, indicating a close association between these 2 processes. The aim of the present study was to identify the underlying mechanisms via profiling of the expression of energy metabolism-related proteins in the left atrial appendage (LAA) of patients with AF. Methods and Results: Isobaric tag for relative and absolute quantification-coupled 2-D liquid chromatography-tandem mass spectrometry (iTRAQ-coupled 2-D LC-MS/MS) was used to profile the expression of energy metabolism-related proteins in the LAA from valvular disease patients with sinus rhythm (SR; n=6) and AF (n=8). Using Protein Pilot 4.0, 122 energy metabolism-related proteins, consisting of 39 carbohydrate metabolism-related proteins, 22 proteins involved in lipid metabolism, 49 biological oxidation-related proteins and 12 other kinds of proteins, were identified. Most of them were key enzymes involved in energy metabolism. Moreover, most of the proteins that were expressed differently in the LAA between the AF and SR patients, and which were related to energy metabolism, were down-regulated. These results were further validated on western blot. Conclusions: Atrial myocardium energy production in valvular disease patients is impaired during permanent AF, and this impairment in energy production may be involved in the matrix of AF formation.