title: Myocardial perfusion reserve and oxidative metabolism contribute to exercise capacity in patients with dilated cardiomyopathy.
abstract: BACKGROUND
  Exercise intolerance is a hallmark symptom in patients with heart failure; however, myocardial factors contributing to the limited exercise capacity are not fully characterized.
  
  
  METHODS
  Twenty patients with stable heart failure resulting from idiopathic dilated cardiomyopathy (DCM) and 13 controls were studied. Myocardial perfusion, biventricular oxidative metabolism, and insulin-stimulated glucose uptake were measured using positron emission tomography and [(15)O]H(2)O, [(11)C]acetate, and [(18)F]FDG.
  
  
  RESULTS
  Hyperemic perfusion and perfusion reserve were significantly lower in the DCM patients compared with the healthy subjects. There was no difference in left ventricular oxidative metabolism between the 2 groups; however, the patients had a 19% higher right ventricular oxidative metabolism (P=.005). Consequently, the ratio of right to left ventricular oxidative metabolism was also higher (31%) in the patients. There was a strong inverse association between decreased exercise capacity and the ratio of right to left ventricular oxidative metabolism (r=-.68, P<.01) and a positive association with myocardial perfusion reserve (r=.62, P<.01) in the patient group. These 2 parameters along with resting left ventricular work explained 57% of the variability in peak exercise capacity.
  
  
  CONCLUSIONS
  Impaired perfusion reserve and an exaggerated imbalance in right to left ventricular oxidative metabolism appear to significantly contribute to the impaired exercise capacity in these DCM patients.
authors.affiliation: Turku PET Centre, Department of Clinical Physiology, University of Turku, Turku, Finland.
authors.forename: Kira Q
authors.initials: KQ
authors.lastname: Stolen
authors.forename: Jukka
authors.initials: J
authors.lastname: Kemppainen
authors.forename: Kari K
authors.initials: KK
authors.lastname: Kalliokoski
authors.forename: Kirsti
authors.initials: K
authors.lastname: Hällsten
authors.forename: Matti
authors.initials: M
authors.lastname: Luotolahti
authors.forename: Hannu
authors.initials: H
authors.lastname: Karanko
authors.forename: Pertti
authors.initials: P
authors.lastname: Lehikoinen
authors.forename: Tapio
authors.initials: T
authors.lastname: Viljanen
authors.forename: Tiina
authors.initials: T
authors.lastname: Salo
authors.forename: K E Juhani
authors.initials: KE
authors.lastname: Airaksinen
authors.forename: Pirjo
authors.initials: P
authors.lastname: Nuutila
authors.forename: Juhani
authors.initials: J
authors.lastname: Knuuti
mesh_terms: D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D016022:Case-Control Studies; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption; D010104:Oxygen Radioisotopes; D019275:Radiopharmaceuticals; D014055:Tomography, Emission-Computed; D016277:Ventricular Function, Left / Q000502:physiology; D014867:Water
chemical_list: D010104:Oxygen Radioisotopes; D019275:Radiopharmaceuticals; D014867:Water; D019788:Fluorodeoxyglucose F18; D005947:Glucose