M Mayr, S Yusuf, G Weir, Y-L Chung, U Mayr, X Yin, C Ladroue, B Madhu, N Roberts, A De Souza, S Fredericks, M Stubbs, JR Griffiths, M Jahangiri, Q Xu, AJ Camm
J Am Coll Cardiol
OBJECTIVES: We sought to decipher metabolic processes servicing the increased energy demand during persistent atrial fibrillation (AF) and to ascertain whether metabolic derangements might instigate this arrhythmia. BACKGROUND: Whereas electrical, structural, and contractile remodeling processes are well-recognized contributors to the self-perpetuating nature of AF, the impact of cardiac metabolism upon the persistence/initiation of this resilient arrhythmia has not been explored in detail. METHODS: Human atrial appendage tissues from matched cohorts in sinus rhythm (SR), from those who developed AF post-operatively, and from patients in persistent AF undergoing cardiac surgery were analyzed using a combined metabolomic and proteomic approach. RESULTS: High-resolution proton nuclear magnetic resonance (NMR) spectroscopy of cardiac tissue from patients in persistent AF revealed a rise in beta-hydroxybutyrate, the major substrate in ketone body metabolism, along with an increase in ketogenic amino acids and glycine. These metabolomic findings were substantiated by proteomic experiments demonstrating differential expression of 3-oxoacid transferase, the key enzyme for ketolytic energy production. Notably, compared with the SR cohort, the group susceptible to post-operative AF showed a discordant regulation of energy metabolites. Combined principal component and linear discriminant analyses of metabolic profiles from proton NMR spectroscopy correctly classified more than 80% of patients at risk of AF at the time of coronary artery bypass grafting. CONCLUSIONS: The present study characterized the metabolic adaptation to persistent AF, unraveling a potential role for ketone bodies, and demonstrated that discordant metabolic alterations are evident in individuals susceptible to post-operative AF.