Elsevier

The Lancet Neurology

Volume 7, Issue 3, March 2008, Pages 216-222
The Lancet Neurology

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Clinical and angiographic risk factors for stroke and death within 30 days after carotid endarterectomy and stent-protected angioplasty: a subanalysis of the SPACE study

https://doi.org/10.1016/S1474-4422(08)70024-3Get rights and content

Summary

Background

Carotid endarterectomy (CEA) and carotid artery stenting (CAS) are used to prevent ischaemic stroke in patients with stenosis of the internal carotid artery. Better knowledge of risk factors could improve assignment of patients to these procedures and reduce overall risk. We aimed to assess the risk of stroke or death associated with CEA and CAS in patients with different risk factors.

Methods

We analysed data from 1196 patients randomised to CAS or CEA in the Stent-Protected Angioplasty versus Carotid Endarterectomy in Symptomatic Patients (SPACE) trial. The primary outcome event was death or ipsilateral stroke (ischaemic or haemorrhagic) with symptoms that lasted more than 24 h between randomisation and 30 days after therapy. Six predefined variables were assessed as potential risk factors for this outcome: age, sex, type of qualifying event, side of intervention, degree of stenosis, and presence of high-grade contralateral stenosis or occlusion. The SPACE trial is registered at Current Controlled Trials, with the international standard randomised controlled trial number ISRCTN57874028.

Findings

Risk of ipsilateral stroke or death increased significantly with age in the CAS group (p=0·001) but not in the CEA group (p=0·534). Classification and regression tree analysis showed that the age that gave the greatest separation between high-risk and low-risk populations who had CAS was 68 years: the rate of primary outcome events was 2·7% (8/293) in patients who were 68 years old or younger and 10·8% (34/314) in older patients. Other variables did not differ between the CEA and CAS groups.

Interpretation

Of the predefined covariates, only age was significantly associated with the risk of stroke and death. The lower risk after CAS versus CEA in patients up to 68 years of age was not detectable in older patients. This finding should be interpreted with caution because of the drawbacks of post-hoc analyses.

Introduction

Extracranial stenosis of the internal carotid artery is an important cause of ischaemic stroke, particularly in patients with recent ischaemic ocular symptoms, transient ischaemic attack (TIA), or stroke. Available treatments include carotid artery stenting (CAS), carotid endarterectomy (CEA), and medical therapy (treatment of vascular risk factors and follow-up of the stenosis with ultrasound). The risk of stroke and death resulting from CEA has been shown to depend on clinical indication.1 CAS and CEA are based on different treatment principles, which might result in different risk characteristics in patients who undergo these procedures. The efficacy of CAS might best be tested in a population for which CEA seems to have a high risk,2 because CAS is potentially less invasive and might have a lower complication rate in medically compromised, high-risk patients than does CEA. Improved assignment of patients with carotid stenosis to each procedure, by the identification of subgroups for treatment with CEA or CAS on the basis of simple variables, might allow the overall risk to be reduced.

The Stent-Protected Angioplasty versus Carotid Endarterectomy in Symptomatic Patients (SPACE) trial was a randomised controlled trial of CEA versus CAS for symptomatic carotid stenosis.3 On the basis of data from this trial, we aimed to analyse the risks of adverse events for these treatments separately. We postulated that complications after CEA and CAS would be associated with different risk factors.

Section snippets

Patients and procedures

Patients were eligible for SPACE if they had amaurosis fugax, hemispherical TIA, or completed stroke in the previous 180 days and had stenosis of the ipsilateral carotid artery that was moderate to severe—ie, 50% or more according to criteria from the North American Symptomatic Carotid Endarterectomy Trial (NASCET),4 or 70% or more according to criteria from the European Carotid Surgery Trial (ECST).5 Further inclusion and exclusion criteria have been specified previously.3 All patients

Results

The intention-to-treat analysis (table 1) included data from 1196 patients, 607 randomly assigned to CAS and 589 randomly assigned to CEA. These numbers differ from those in the previous analysis3 because 14 more patients were assigned to treatment between the interim analysis and the end of the trial, and six patients assigned to CAS and 12 assigned to CEA withdrew consent before therapy. The per-protocol analysis (table 2) included data from 573 (94%) patients in the CAS group and 563 (96%)

Discussion

Bond and colleagues1 reported associations of factors with a higher than average risk from CEA in a combined analysis of data from NASCET and ECST. Risk was higher when the qualifying event was TIA than if it was amaurosis fugax,1 and was higher when the contralateral internal carotid artery was occluded than when it was not.9 For CAS, risk factors for periprocedural complications are less well defined. Trials presented at scientific meetings include Acculink for Revascularization of Carotids

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