Ischemic stroke events and carotid atherosclerosis. Results of the Osaka Follow-up Study for Ultrasonographic Assessment of Carotid Atherosclerosis (the OSACA Study)

Abstract

Background and purpose: To clarify the clinical significance of carotid atherosclerosis for ischemic stroke events, a follow-up study was performed in Japanese patients.

Methods: Two hundred fourteen patients were registered from nine hospitals in the Osaka community. All patients were checked for a prior history of stroke, and the risk factors for stroke and atherosclerosis were evaluated. Carotid atherosclerosis was assessed by 7.5-MHz duplex ultrasonography. We studied the relationship between the ischemic stroke event rate and the severity and appearance of the carotid atherosclerosis. We also studied the relationship between stroke events and various risk factors.

Results: The average duration of follow-up was 16 months. Ten patients suffered new ischemic stroke episodes during this follow-up period. At the initial ultrasonographic study, 16 patients had high-grade stenosis and 21 had ulcerated plaque. Proportional hazard regression analysis showed that grade of stenosis and plaque ulceration were positively related to the event rate. Patients with ulcerated plaque had a sevenfold higher hazard ratio for stroke in comparison to those without (P < .01). The ipsilateral stroke recurrence rate was 11 times higher in patients with ulcerated high-grade stenotic carotid lesions.

Conclusions: The present findings demonstrate that the severity of carotid atherosclerosis as evaluated by ultrasonography is a useful indicator of the risk of ischemic stroke in symptomatic patients.