title: Heart failure with preserved ejection fraction is characterized by dynamic impairment of active relaxation and contraction of the left ventricle on exercise and associated with myocardial energy deficiency.
abstract: OBJECTIVE
  We sought to evaluate the role of exercise-related changes in left ventricular (LV) relaxation and of LV contractile function and vasculoventricular coupling (VVC) in the pathophysiology of heart failure with preserved ejection fraction (HFpEF) and to assess myocardial energetic status in these patients.
  
  
  BACKGROUND
  To date, no studies have investigated exercise-related changes in LV relaxation and VVC as well as in vivo myocardial energetic status in patients with HFpEF.
  
  
  METHODS
  We studied 37 patients with HFpEF and 20 control subjects. The VVC and time to peak LV filling (nTTPF, a measure of LV active relaxation) were assessed while patients were at rest and during exercise by the use of radionuclide ventriculography. Cardiac energetic status (creatine phosphate/adenosine triphosphate ratio) was assessed by the use of (31)P magnetic resonance spectroscopy at 3-T.
  
  
  RESULTS
  When patients were at rest, nTTPF and VVC were similar in patients with HFpEF and control subjects. The cardiac creatine phosphate/adenosine triphosphate ratio was reduced in patients with HFpEF versus control subjects (1.57 +/- 0.52 vs. 2.14 +/- 0.63; p = 0.003), indicating reduced energy reserves. Peak maximal oxygen uptake and the increase in heart rate during maximal exercise were lower in patients with HFpEF versus control subjects (19 +/- 4 ml/kg/min vs. 36 +/- 8 ml/kg/min, p < 0.001, and 52 +/- 16 beats/min vs. 81 +/- 14 beats/min, p < 0.001). The relative changes in stroke volume and cardiac output during submaximal exercise were lower in patients with HFpEF versus control subjects (ratio exercise/rest: 0.99 +/- 0.34 vs. 1.25 +/- 0.47, p = 0.04, and 1.36 +/- 0.45 vs. 2.13 +/- 0.72, p < 0.001). The nTTPF decreased during exercise in control subjects but increased in patients with HFpEF (-0.03 +/- 12 s vs. +0.07 +/- 0.11 s; p = 0.005). The VVC decreased on exercise in control subjects but was unchanged in patients with HFpEF (-0.01 +/- 0.15 vs. -0.25 +/- 0.19; p < 0.001).
  
  
  CONCLUSIONS
  Patients with HFpEF have reduced cardiac energetic reserve that may underlie marked dynamic slowing of LV active relaxation and abnormal VVC during exercise.
authors.affiliation: Department of Cardiovascular Medicine, University of Birmingham, Vincent Drive, Edgbaston, Birmingham B15 2TT, United Kingdom. ttpquang@hotmail.com
authors.forename: Thanh T
authors.initials: TT
authors.lastname: Phan
authors.forename: Khalid
authors.initials: K
authors.lastname: Abozguia
authors.forename: Ganesh
authors.initials: G
authors.lastname: Nallur Shivu
authors.forename: Gnanadevan
authors.initials: G
authors.lastname: Mahadevan
authors.forename: Ibrar
authors.initials: I
authors.lastname: Ahmed
authors.forename: Lynne
authors.initials: L
authors.lastname: Williams
authors.forename: Girish
authors.initials: G
authors.lastname: Dwivedi
authors.forename: Kiran
authors.initials: K
authors.lastname: Patel
authors.forename: Paul
authors.initials: P
authors.lastname: Steendijk
authors.forename: Houman
authors.initials: H
authors.lastname: Ashrafian
authors.forename: Anke
authors.initials: A
authors.lastname: Henning
authors.forename: Michael
authors.initials: M
authors.lastname: Frenneaux
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D004734:Energy Metabolism; D015444:Exercise / Q000502:physiology*; D005260:Female; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology*