Myocardial oxidative metabolism is increased due to haemodynamic overload in patients with aortic valve stenosis: assessment using 11C-acetate positron emission tomography.
OBJECTIVE
The relationship between myocardial oxidative metabolism and pressure overload in aortic valve stenosis (AS) is not fully elucidated. We identified the determinants of myocardial oxidative metabolism by measuring its changes after aortic valve replacement (AVR) in patients with AS.


METHODS
Myocardial 11C-acetate clearance rate constant (Kmono), an index of oxidative metabolism, was measured non-invasively by using positron emission tomography in 16 patients with moderate to severe AS and 7 healthy controls. The severity of AS was assessed by echocardiography. Of 16 patients, 5 were reexamined at 1 month after AVR.


RESULTS
Kmono was significantly higher in patients with AS than healthy controls by 42% (0.068±0.014 vs 0.048±0.007/min, p<0.01). Kmono was significantly correlated with age (r=0.58, p<0.01), left ventricular (LV) mass index (r=0.61, p<0.01) and estimated systolic LV pressure (r=0.81, p<0.001) measured by echocardiography. By multivariate analysis, estimated LV systolic pressure was an independent predictor of Kmono (β=0.93, p<0.01). After AVR, Kmono (from 0.075±0.012 to 0.061±0.014/min, p=0.043) and LV mass index (from 183±49 to 124±41 g/ml2, p=0.043) were significantly decreased despite no significant changes in rate-pressure product.


CONCLUSIONS
Myocardial oxygen metabolism was increased in patients with AS, which was decreased after AVR. The increased myocardial oxidative metabolism in AS was largely attributable to the pressure overload of the LV.
Naya
Masanao
M
Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Kita 15, Nishi 7, Kita-ku, Sapporo, 060-8638, Japan. naya@med.hokudai.ac.jp
Chiba
Satoru
S
Iwano
Hiroyuki
H
Yamada
Satoshi
S
Katoh
Chietsugu
C
Manabe
Osamu
O
Yoshinaga
Keiichiro
K
Matsui
Yoshiro
Y
Tamaki
Nagara
N
Tsutsui
Hiroyuki
H
D000085:Acetates / Q000493:pharmacokinetics*; D000368:Aged; D001024:Aortic Valve Stenosis / Q000150:complications / Q000000981:diagnostic imaging* / Q000378:metabolism*; D002244:Carbon / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D010084:Oxidation-Reduction; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000000981:diagnostic imaging* / Q000378:metabolism*
D000085:Acetates; D019275:Radiopharmaceuticals; C438206:carbon-11 acetate; D002244:Carbon