During health, beta oxidation of long-chain fatty acids is the primary contributor to the acetyl-CoA pool, with that derived from glucose (via glycolysis) becoming predominant during adrenergic stress,10 ischaemia11 and during the later stages of heart failure.12 Hyperpolarised imaging can also quantify these cellular switches due to the associated alterations in PDH flux in various pathological states. The gene discussed is PDP1; the disease is heart failure.