IMPORTANCE OF HEMODYNAMIC FACTORS IN THE PROGNOSIS OF SYMPTOMATIC CAROTID OCCLUSION

Context.-The relative importance of hemodynamic factors in the pathoge nesis and treatment of stroke in patients with carotid artery occlusio n remains controversial. Objective.-To test the hypothesis that stage II cerebral hemodynamic failure (increased oxygen extraction measured by positron emission tomography [PET]) distal to symptomatic carotid a rtery occlusion is an independent risk factor for subsequent stroke in medically treated patients. Design and Setting.-Prospective, blinded, longitudinal cohort study of patients referred from a group of region al hospitals between 1992 and 1996, Patients.-From 419 subjects referr ed, 81 with previous stroke or transient ischemic attack in the territ ory of an occluded carotid artery were enrolled. All were followed up to completion of the study, with average follow-up of 31.5 months. Mai n Outcome Measures.-Telephone contact every 6 months recorded the subs equent occurrence of all stroke, ipsilateral ischemic stroke, and deat h. Results.-Stroke occurred in 12 of 39 patients with stage II hemodyn amic failure and in 3 of 42 patients without (P=.005); stroke was ipsi lateral in 11 of 39 patients with stage II hemodynamic failure and in 2 of 42 patients without (P=.004). Six deaths occurred in each group ( P=.94). The age-adjusted relative risk conferred by stage II hemodynam ic failure was 6.0 (95% confidence interval [CI], 1.7-21.6) for all st roke and 7.3 (95% CI, 1.6-33.4) for ipsilateral stroke. Conclusions.-S tage II hemodynamic failure defines a subgroup of patients with sympto matic carotid occlusion who are at high risk for subsequent stroke whe n treated medically, A randomized trial evaluating surgical revascular ization in this high-risk subgroup is warranted.