Outcome in elderly patients with low-grade stenotic lesions of the extracranial carotid artery

Abstract

To evaluate the outcome in patients with low-grade stenotic lesions of the extracranial carotid artery, 347 consecutive outpatients aged 60 years or older were studied with regard to outcome after performing examinations by carotid ultrasonography and platelet function tests. They had a variety of disease, including 107 patients with cerebrovascular disease and 77 patients with dizziness, although patients with high-grade carotid artery stenosis of more than 70% of the vessel diameter were excluded. The mean age was 77.5 years, and the patients consisted of 161 men and 186 women. Based on the ultrasonographic findings, carotid lesions were defined as having plaque or stenosis of 50-70% of the vessel diameter. Plaques, defined as thickened intimamedia complexes of 2.1 mm or more in height, were classified into 2 types according to their morphometric dimensions (nodular and mural plaques). The patients were divided into 3 groups based on the number of carotid artery lesions: the no lesion group (n=153), which had no carotid lesion; the unilateral lesion group (n=103), which had a unilateral carotid lesion; and the bilateral lesion group (n=91), which revealed carotid lesions bilaterally. The patients were also divided into 4 groups on the basis of the plaque morphometry: the nodular plaque group (n=66), which had nodular plaque only; the mural plaque group (n=118), which had mural plaque with or without nodular plaque; the stenotic group (n=10), which revealed stenosis of 50-70 % of the vessel diameter ; and the no lesion group. Platelet function was assessed using a platelet aggregometer with adenosine-5' -diphosphate. At baseline, the mean age as well as the incidence of advanced thrombotic diseases and total dependence in the ADL status was higher in the bilateral lesion group and mural plaque group than in the no lesion group. The mean follow-up period was 3.9 years. A total of 66 patients died, and the most common cause of death was pneumonia, followed by vascular events. The annual mortality rate due to vascular events was 0.5% in the no lesion group and 1.7% in the unilateral lesion group, while the rate was 4.0% in the bilateral lesion group. Furthermore, the annual mortality rate due to vascular events was 1.8% in the nodular plaque group, 3.6% in the mural plaque group, and 0% in the stenotic group. Log-rank statistics derived from Kaplan-Meier survival curves showed these rates to be significantly higher in both the bilateral lesion group and the mural plaque group than in the no lesion group. The Cox proportional hazards model for death due to vascular events demostrated a significantly high hazard ration in the bilateral lesion group, the mural plaque group, and the accelerated platelet function group. These findings suggested that, in addition to undertaking further assessments of vascular lesions and control of vascular risks, antiplatelet therapy should be performed in those patients with bilateral carotid lesions or mural plaque to prevent vascular events.