Background Information on outcome of patients with occlusion of the internal carotid artery (ICA) is limited by the short duration of follow-up and lack of haemodynamic studies on the brain.

Methods The authors prospectively investigated 117 consecutive patients with transient or moderately disabling cerebral or retinal ischaemia associated with ICA occlusion between September 1995 and July 1998, and followed them until June 2008. The authors determined the risk of recurrent ischaemic stroke and other vascular events and prognostic factors, including collateral pathways and transcranial Doppler CO₂ reactivity.

Results Patients (mean age 61±9 years; 80% male) were followed for a median time of 10.2 years; 22 patients underwent endarterectomy for contralateral ICA stenosis and 16 extracranial/intracranial bypass surgery. Recurrent ischaemic stroke occurred in 23 patients, resulting in an annual rate of 2.4% (95% CI 1.5 to 3.6). Risk factors for recurrent ischaemic stroke were age (HR 1.07, 1.02 to 1.13), cerebral rather than retinal symptoms (HR 8.0, 1.1 to 60), recurrent symptoms after documented occlusion (HR 4.4, 1.6 to 12), limb-shaking transient ischaemic attacks at presentation (HR 7.5, 2.6 to 22), history of stroke (HR 2.8, 1.2 to 6.7) and leptomeningeal collaterals (HR 5.2, 1.5 to 17) but not CO₂ reactivity (HR 1.01, 0.99 to 1.02). The composite event of any vascular event occurred in 57 patients, resulting in an annual rate of 6.4% (95% CI 4.9 to 8.2).

Conclusion The prognosis of patients with transient ischaemic attack or minor stroke and ICA occlusion depends on age, several clinical factors and the presence of leptomeningeal collaterals. The long-term risk of recurrent ischaemic stroke is much lower than that of other vascular events.