[Cerebral hemodynamics and risk for recurrent stroke in symptomatic internal carotid artery occlusion].

Purpose: In internal carotid artery occlusion, patients with inadequate blood supply relative to metabolic demand (misery perfusion) may be at increased risk for cerebral ischemia. This study investigated whether patients demonstrating misery perfusion on positron emission tomography (PET) have a high risk of subsequent stroke in symptomatic internal carotid artery occlusion.

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 artery occlusion who underwent PET. Patients were divided into two hemodynamic categories according to the mean hemispheric value of oxygen extraction fraction (OEF) in the hemisphere supplied by the artery with symptomatic disease: patients with increased OEF and those with normal OEF. All patients were followed with medical treatment until the recurrence of stroke or death for 3 years.

Results: The three-year incidence of ipsilateral ischemic strokes for patients with normal OEF and those with increased OEF were 1 of 34 and 3 of 6 patients, respectively. A significantly higher incidence of ipsilateral strokes was found in patients with increased OEF (Kaplan-Meier analysis and log-rank test; p < 0.001). Multivariate analysis with the Cox proportional hazards model demonstrated that increased OEF significantly increased stroke recurrence: the relative risk was 19.5 (95% CI, 2.0-188.6) for ipsilateral stroke. An increase in the absolute OEF value was a better predictor of recurrent ischemic stroke than an OEF asymmetry.

Conclusion: These findings suggest that patients with symptomatic internal carotid artery occlusion and misery perfusion have a high risk for subsequent stroke. Thus, identification and optimal treatment of patients with misery perfusion may be essential in preventing stroke.