Myocardial perfusion reserve and oxidative metabolism contribute to exercise capacity in patients with dilated cardiomyopathy.
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.
Stolen
Kira Q
KQ
Turku PET Centre, Department of Clinical Physiology, University of Turku, Turku, Finland.
Kemppainen
Jukka
J
Kalliokoski
Kari K
KK
Hällsten
Kirsti
K
Luotolahti
Matti
M
Karanko
Hannu
H
Lehikoinen
Pertti
P
Viljanen
Tapio
T
Salo
Tiina
T
Airaksinen
K E Juhani
KE
Nuutila
Pirjo
P
Knuuti
Juhani
J
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
D010104:Oxygen Radioisotopes; D019275:Radiopharmaceuticals; D014867:Water; D019788:Fluorodeoxyglucose F18; D005947:Glucose