Abstract
AIMS: Heart failure (HF) with preserved ejection fraction (HFpEF) reflects half of all clinical HF yet has few therapies. Obesity and diabetes are now common comorbidities which have focused attention towards underlying myocardial metabolic defects. The profile of a major metabolic pathway, glycolytic intermediates and their regulating enzymes and ancillary pathways, remains unknown. METHODS AND RESULTS: Endomyocardial biopsies from HFpEF (n = 37) and non-failing controls (n = 21) were assayed by non-targeted or targeted metabolomics and immunoblot to determine glycolytic and ancillary pathway metabolites and protein expression of their regulating enzymes. Glucose and GLUT1 expression were higher in HFpEF, but prominent glycolytic metabolites: glucose-6-phosphate, fructose-1,6-biphosphate (F1,6bP), and 3-phosphoglycerate were reduced by -78%, -91%, and -73%, respectively, versus controls. Expression of their corresponding synthesizing enzymes hexokinase, phospho-fructokinase, and phosphoglycerate kinase were also significantly lower (all p < 0.0005). Pentose phosphate and hexosamine biosynthetic pathway metabolites were reduced while glycogen content increased. Despite proximal reduction in key glycolytic intermediates, pyruvate increased but mitochondrial pyruvate transporter (MPC1) expression was reduced. Pyruvate dehydrogenase converting pyruvate to acetyl-CoA was more activated but some Krebs cycle intermediates were reduced. This HFpEF glycolytic profile persisted after adjusting for body mass index (BMI), diabetes, age, and sex, or in subgroup analysis with controls and HFpEF matched for BMI and diabetes/insulin history. In HFpEF, BMI but not glycated haemoglobin negatively correlated with F1,6bP (p = 7e-5, r = -0.61) and phosphoenolpyruvate (p = 0.006, r = -0.46). CONCLUSIONS: Human HFpEF myocardium exhibits reduced glycolytic and ancillary pathway intermediates and expression of their synthesizing proteins. This combines features reported in HF with reduced ejection fraction and obesity/diabetes that likely exacerbate metabolic inflexibility.