ICSS Final Results Still Favor Endarterectomy Over Stenting

Daniel M. Keller, PhD

July 05, 2012

July 5, 2012 (Lisbon, Portugal) — The primary analysis from the International Carotid Stenting Study (ICSS) shows that for symptomatic patients with carotid artery stenosis, carotid endarterectomy (CEA) remains the treatment of choice over carotid artery stenting (CAS).

"Although there was no difference between the treatment groups in the rate of fatal or disabling stroke — the primary outcome of the study — CAS was associated with a 56% greater likelihood of any stroke outcome during long-term follow up," said Martin Brown, MB BCh, MD, professor of stroke medicine at the Institute of Neurology, University College London, United Kingdom. However, he noted that long-term rates of stroke are low after either treatment.

These results were presented here at the XXI European Stroke Conference. Interim 120-day safety results from ICSS were published in 2010 in The Lancet. Those results appeared to favor carotid endarterectomy over carotid stenting for patients with symptomatic carotid stenosis, with higher rates of stroke, death, and periprocedural myocardial infarction (MI) in patients treated with stenting vs endarterectomy.

The ICSS results were seen as at odds with results of the Carotid Revascularization Endarterectomy versus Stenting Trial (CREST), which were presented the next day after The Lancet publication, and showed similar net outcomes with CAS and CEA for the primary endpoint of any stroke, MI, or death during the periprocedural period or ipsilateral stroke on follow-up, in patients with both symptomatic and asymptomatic carotid stenosis. At 30 days, however, stroke was significantly higher with CAS, although major stroke was not different, and MI risk was higher with CEA. Interpretation of these results in the stroke community has been controversial.

ICSS Results

By recruiting patients at 50 centers in 15 countries between 2002 and 2008, ICSS aimed to determine the risks and long-term benefits of CAS vs CEA for patients with symptomatic carotid stenosis. Baseline characteristics of the groups were well matched, and follow-up continued until this year.

The ICSS included patients with extracranial atherosclerotic stenosis greater than 50% in the internal carotid artery that caused recent, relevant symptoms. Individuals with lesions that were suitable for both treatments were randomly assigned to one or the other, treated, and then followed up annually.

Major outcome events were independently adjudicated in a manner blinded to treatment allocation. The median follow-up for both interventions was 4.2 years, with a total of 7350 patient-years.

Reporting an intention-to-treat analysis from the time of treatment, Dr. Brown told the delegates, "Our primary outcome event was fatal or disabling stroke, and as you can see, there was no difference in the numbers or the hazard ratio of fatal or disabling stroke comparing stenting with endarterectomy, with a hazard ratio of 1.08 [95% confidence interval {CI}, 0.73 - 1.60; P = .69]."

Among 853 patients assigned to CAS, 53 events occurred vs 49 among 857 patients assigned to CEA.

Most events occurred at the time of treatment. Over the next 6 years, very few events were reported in either group, the event rate was about 0.5%/year, and the groups were well matched for fatal or disabling stroke.

However, CEA was significantly more efficacious than CAS in preventing any form of stroke more than 30 days after completion of treatment, which excludes all perioperative treatment–related events and patients who did not receive treatment (hazard ratio [HR] for CAS, 1.56; 95% CI, 1.04 - 2.35; P = .031).

At 1 year (+31 days), the rate of occurrence of any stroke was 1.8% vs 2.9%, respectively, and at 5 years (+31 days), the rate was 5.8% vs 9.2%, respectively. Dr. Brown said that the difference appeared to be driven mostly by the occurrence of contralateral stroke.

When performing an exploratory subgroup analysis for risks of a fatal or disabling stroke, the investigators found no significant interaction for any subgroup.

CAS was associated with a higher rate of all other stroke outcomes, including any stroke, fatal stroke, ipsilateral stroke, ipsilateral stroke plus stroke or death within 30 days of treatment, contralateral stroke, and fatal MI.

Dr. Brown concluded that CEA "remains the treatment of choice for symptomatic carotid stenosis," although "the rates of long-term stroke are low" after either CEA or CAS.

He said that further research will be required to explain the impact of increased nondisabling stroke after CAS, and to explore why the rate of contralateral stroke was higher after CAS.

The study received funding from Sanofi-Synthélabo in 2001 to assist in setting it up, and there has been no commercial funding since that time. Dr. Brown has disclosed no commercial interests and no other relevant financial relationships.

XXI European Stroke Conference. No abstract number. Presented May 23, 2012.

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