title: Resting cardiac energy metabolism is inversely associated with heart rate in healthy young adult men.
abstract: BACKGROUND
  31-Phosphorus-magnetic resonance spectroscopy may provide pathophysiological insights into the high-energy phosphate metabolism of the myocardium as measured by phosphocreatine to adenosine triphosphate (PCr/ATP) ratio. Aim of the present study was to determine in vivo the relation between cardiac PCr/ATP ratio and heart rate in normal male subjects.
  
  
  METHODS
  One hundred twelve apparently healthy, young male individuals (age 34 ± 10 years) were prospectively evaluated. They underwent cardiac cine magnetic resonance imaging to assess left ventricular (LV) function and morphology and 3D-ISIS (31)P-magnetic resonance spectroscopy of the LV to assess the PCr/ATP ratio (a recognized in vivo marker of myocardial energy metabolism). Data were analyzed after segregation by tertiles of the resting PCr/ATP ratio.
  
  
  RESULTS
  A significant inverse association between PCr/ATP ratios and resting heart rate was observed (Spearman ρ: r=-0.37; P < .0001). PCr/ATP ratios were also inversely associated with body mass index, diastolic blood pressure, wall mass and with insulin resistance, but in multiple regression analysis heart rate was found to be independently related to PCr/ATP.
  
  
  CONCLUSIONS
  The present study shows that resting heart rate is proportionally lower across tertiles of increasing PCr/ATP ratio of the LV in apparently healthy young male individuals, supporting the hypothesis that heart rate is a major determinant of cardiac energy stores. These findings may explain the prognostic role of heart rate in the general population as evidenced by previous large epidemiological studies.
authors: Cardio-Thoracic and Vascular Department-Clinical Cardiology, Istituto Scientifico-Universita' Vita/Salute San Raffaele, Milano, Italy. gabriele.fragasso@hsr.it
authors: Gabriele
authors: G
authors: Fragasso
authors: Francesco
authors: F
authors: De Cobelli
authors: Roberto
authors: R
authors: Spoladore
authors: Antonio
authors: A
authors: Esposito
authors: Anna
authors: A
authors: Salerno
authors: Giliola
authors: G
authors: Calori
authors: Claudia
authors: C
authors: Montanaro
authors: Francesco
authors: F
authors: Maranta
authors: Guido
authors: G
authors: Lattuada
authors: Alberto
authors: A
authors: Margonato
authors: Alessandro
authors: A
authors: Del Maschio
authors: Gianluca
authors: G
authors: Perseghin
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000328:Adult; D004734:Energy Metabolism / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006352:Heart Ventricles / Q000378:metabolism; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D010725:Phosphocreatine / Q000031:analogs & derivatives* / Q000378:metabolism; D011446:Prospective Studies; D012016:Reference Values; D012146:Rest / Q000502:physiology*; D016277:Ventricular Function, Left / Q000502:physiology*
chemical_list: D010725:Phosphocreatine; C025403:phosphocreatinine; D000255:Adenosine Triphosphate