Insights Into the Metabolic Aspects of Aortic Stenosis With the Use of Magnetic Resonance Imaging.

Pressure overload in aortic stenosis (AS) encompasses both structural and metabolic remodeling and increases the risk of decompensation into heart failure. A major component of metabolic derangement in AS is abnormal cardiac substrate use, with down-regulation of fatty acid oxidation, increased reliance on glucose metabolism, and subsequent myocardial lipid accumulation. These changes are associated with energetic and functional cardiac impairment in AS and can be assessed with the use of cardiac magnetic resonance spectroscopy (MRS). Proton MRS allows the assessment of myocardial triglyceride content and creatine concentration. Phosphorous MRS allows noninvasive in vivo quantification of the phosphocreatine-to-adenosine triphosphate ratio, a measure of cardiac energy status that is reduced in patients with severe AS. This review summarizes the changes to cardiac substrate and high-energy phosphorous metabolism and how they affect cardiac function in AS. The authors focus on the role of MRS to assess these metabolic changes, and potentially guide future (cellular) metabolic therapy in AS. [Display omitted] • Understanding the cellular pathophysiologic processes in ASmay help to identify patients likely to decompensate early, and to explore potential therapeutic targets that could delay disease progression. • Altered cardiac substrate utilization and consequent myocardial steatosis and reduced energy efficiency has been implicated in the transition from compensated hypertrophy to heart failure in AS. • Magnetic resonance spectroscopy allows detailed assessment of changes to cardiac substrate and high-energy phosphorous metabolism, improving our understanding of the links between abnormal metabolism and impairment of cardiac function in AS. [ABSTRACT FROM AUTHOR]