Abstract 2834: A Short-Term High Fat Diet Impairs Cardiac High Energy Phosphate Metabolism, Exercise Capacity and Cognitive Function

Background: Heart failure patients have low cardiac phosphocreatine/ATP (PCr/ATP) ratios, abnormal exercise tolerance and impaired cognitive function, which may be related to elevated circulating free fatty acids (FFAs). We tested whether briefly raising plasma FFAs, using diet, causes abnormalities in heart, brain and skeletal muscle in healthy subjects Methods and Results: Healthy males (n = 16, age 22 ± 1 years), recruited from the University of Oxford, were randomised to five days of a high fat diet containing 75 ± 1% of calorie intake through fat consumption, or an isocaloric control diet, providing 23 ± 1% of calorie intake as fat. In a cross-over design, subjects undertook the alternate diet after a two week wash out period. Cardiac 31 P magnetic resonance (MR) spectroscopy and MR imaging, echocardiography, exhaustive cycling for 1 h, and CDR computerised cognitive tests were used to assess cardiac PCr/ATP, cardiac function, exercise capacity and cognitive function, respectively, before and after the diets. Subjects on the HFD had a two-fold elevation in plasma FFAs, 12% lower cardiac PCr/ATP with no change in cardiac function, and a 12% lower maximal exercise performance (see Figure ). They also had impaired attention and speed (2.2 vs. 1.9 s, p < 0.001, and 1.10 vs. 1.05 s, respectively, p < 0.01) Discussion: We have shown a short term, high fat diet raised plasma FFA concentrations, impaired myocardial energetics, exercise capacity and cognition. Therefore high plasma FFAs may be detrimental for heart, skeletal muscle and brain in normal subjects and suggests a potential mechanism of impairment in heart failure patients.