title: Effects of weight loss on myocardial energetics and diastolic function in obesity.
abstract: A reduced myocardial phosphocreatine/adenosine triphosphate (PCr/ATP) ratio is linked to both diastolic dysfunction and heart failure. Although obesity is well known to cause diastolic dysfunction a link to impaired cardiac energetics has only recently been established. We assessed whether or not long-term weight loss in obesity, which is known to reduce mortality, is accompanied by both improved cardiac energetics and diastolic function. Normal weight (BMI 22 ± 2; n = 18) and obese subjects (BMI 34 ± 4; n = 13) underwent cine-MRI (1.5 Tesla) to determine left ventricular diastolic function using volume-time curve analysis, and (31)P-MR spectroscopy (3 Tesla) to assess cardiac energetics (PCr/ATP ratio). Obese subjects (n = 13) underwent repeat assessment after 1 year of supervised weight loss. Obesity, in the absence of identifiable cardiovascular risk factors, was associated with significantly impaired myocardial high energy phosphate metabolism (PCr/ATP ratio, normal; 2.03 ± 0.27 vs. obese; 1.58 ± 0.47, p = 0.002) and significantly lower peak diastolic filling rate (normal; 4.8 ± 0.8 vs. obese; 3.8 ± 0.7 EDV/s, p = 0.01). Weight loss (on average 9 kg, 55% excess weight) over 1 year resulted in a 24% increase in PCr/ATP ratio (p = 0.01) and an 18% improvement in peak diastolic filling rate (p = 0.01). Myocardial PCr/ATP ratio remained positively correlated with peak diastolic filling rate after weight loss (r = 0.63, p = 0.02). In obesity, weight loss improves impaired cardiac energetics and myocardial relaxation. Improved myocardial energetics appear to play a key role in diastolic functional recovery accompanying weight loss.
authors.affiliation: Department of Cardiovascular Medicine, John Radcliffe Hospital, Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford OX3 9DU, UK. oliver.rider@gmail.com
authors.forename: O J
authors.initials: OJ
authors.lastname: Rider
authors.forename: J M
authors.initials: JM
authors.lastname: Francis
authors.forename: D
authors.initials: D
authors.lastname: Tyler
authors.forename: J
authors.initials: J
authors.lastname: Byrne
authors.forename: K
authors.initials: K
authors.lastname: Clarke
authors.forename: S
authors.initials: S
authors.lastname: Neubauer
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D050154:Adiposity; D000328:Adult; D015992:Body Mass Index; D003971:Diastole; D004734:Energy Metabolism; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine; D009682:Magnetic Resonance Spectroscopy; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D009765:Obesity / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D010725:Phosphocreatine / Q000378:metabolism; D020127:Recovery of Function; D013997:Time Factors; D016896:Treatment Outcome; D016277:Ventricular Function, Left; D015431:Weight Loss
chemical_list: D010725:Phosphocreatine; D000255:Adenosine Triphosphate