Significance of increased oxygen extraction fraction in five-year prognosis of major cerebral arterial occlusive diseases.
In major cerebral arterial occlusive diseases, patients with increased oxygen extraction fraction (OEF), which is measured with PET, may be at increased risk for cerebral ischemia. However, the clinical significance of increased OEF remains unclear. This study investigated whether increased OEF is an independent predictor of 5-y risk of subsequent stroke.


METHODS
We prospectively evaluated the relationship between the regional hemodynamic status of cerebral circulation and the subsequent risk of stroke in 40 patients with symptomatic internal carotid or middle cerebral arterial occlusive diseases who underwent PET. Patients were divided into two hemodynamic categories according to the mean hemispheric value of OEF-in the hemisphere supplied by the artery with symptomatic disease: one group with increased OEF and one with normal OEF. All patients were followed for 5 y with medical treatment until the recurrence of stroke or death.


RESULTS
During 5 y, 11 total and 9 ipsilateral ischemic strokes occurred. The incidences of all ischemic strokes in patients with increased OEF and in those with normal OEF were 5 of 7 and 6 of 33 patients, respectively. There were 4 ipsilateral ischemic strokes in patients with increased OEF and 5 in those with normal OEF. Kaplan-Meier analysis revealed that the risks of all stroke and ipsilateral ischemic stroke in patients with increased OEF were significantly higher than in those with normal OEF (log-rank test; P<0.0002 and P<0.0018, respectively). Multivariate analysis with the Cox proportional hazards model showed that increased OEF significantly increased stroke recurrence: the relative risk was 7.2 (95% confidence interval [CI], 2.0-25.5; P<0.005) for all stroke and 6.4 (95% CI, 1.6-26.1; P<0.01) for ipsilateral stroke. An increase in the absolute OEF value was a better predictor of recurrent ischemic stroke than was OEF asymmetry.


CONCLUSIONS
These findings suggest that an increased OEF is an independent predictor of 5-y risk of subsequent stroke. Identification of patients with increased OEF may have clinical significance in preventing recurrent stroke.
Yamauchi
H
H
Research Institute, Department of Neurology, Shiga Medical Center for Adults, Moriyama-City, Japan.
Fukuyama
H
H
Nagahama
Y
Y
Nabatame
H
H
Ueno
M
M
Nishizawa
S
S
Konishi
J
J
Shio
H
H
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001810:Blood Volume; D002545:Brain Ischemia / Q000000981:diagnostic imaging; D002560:Cerebrovascular Circulation; D002561:Cerebrovascular Disorders / Q000000981:diagnostic imaging* / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D011379:Prognosis; D012008:Recurrence; D012307:Risk Factors; D020521:Stroke / Q000000981:diagnostic imaging; D014055:Tomography, Emission-Computed