Study Points to Short-term Advantage for Carotid Endarterectomy Over Stenting

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Carotid endarterectomy may carry better in-hospital outcomes than carotid stenting, regardless of patient age or sex, suggests a retrospective analysis published online October 9, 2014, ahead of print in Stroke. The findings were consistent in both asymptomatic and symptomatic patients.

“Collectively, these results demonstrate the perioperative superiority of endarterectomy to carotid stenting in a real-world setting, even when much of the selection bias has been mitigated using propensity-score matching,” write Robert J. McDonald, MD, PhD, of the Mayo Clinic (Rochester, MN), and colleagues. “Given these findings, the safety of carotid artery stenting should be more rigorously scrutinized, particularly among individuals who are symptomatic at the time of carotid revascularization.”

Researchers looked at retrospective data covering 2006 to 2011 from the Premier Perspective Database, which by the end of the study period represented about 15% of hospitalizations in the United States and more than 600 hospitals. After propensity-score matching based on 33 clinical factors associated with carotid revascularization, the analysis included 24,004 asymptomatic patients and 3,506 symptomatic patients split evenly between endarterectomy and stenting. Median age was roughly 71 years, and about 40% of patients were female.

The rate of in-hospital mortality, stroke, or acute MI (primary endpoint) was higher after stenting than endarterectomy in both asymptomatic and symptomatic patients; the findings were unaffected by age or sex. Similar results were seen when acute MI was left out of the composite endpoint (table 1). The advantage for surgery grew larger as patient age increased.

Table 1. In-Hospital Outcomes: Stenting vs Endarterectomya



95% CI

Mortality, Stroke, or Acute MI









Mortality or Stroke









a P < .0001 for all.

Mortality was higher after stenting than surgery in both asymptomatic and symptomatic patients, although the rate of postoperative stroke or hemorrhage was only higher after stenting in symptomatic patients. The incidence of acute MI did not differ between the revascularization strategies.

Patients who underwent stenting were more likely to develop subarachnoid or intracranial hemorrhage, regardless of symptom status. Stenting also was associated with a greater likelihood of being discharged into a long-term care environment but only among symptomatic patients.

Findings Consistent With Some—but Not All—Trials

The relative perioperative safety of stenting vs endarterectomy has varied across trials comparing the 2 procedures, including CAVATAS, EVA3S, ICSS, SPACE, SAPPHIRE, and CREST. In CREST, 30-day rates of death and stroke did not differ between the strategies; in EVA3S and ICSS, however, rates of both outcomes were higher after stenting.

“Our propensity-score–matched retrospective study complements these prospective studies by leveraging the sample size benefits of a nationwide retrospective hospital discharge database to better quantify the frequency of uncommon adverse outcomes, because these outcomes are often inadequately sampled in prospective studies to permit meaningful comparisons between revascularization therapies,” Dr. McDonald and colleagues write.

Differing in several ways from the findings of CREST, the retrospective data did not show comparable perioperative safety between the 2 procedures and demonstrated a greater advantage for surgery in older patient and more unfavorable outcomes in symptomatic patients. In addition—unlike in CREST—the rate of acute MI was not higher after surgery.

The authors note that the discrepancy between the analyses could be explained at least in part by the CREST’s inclusion of only experienced operators.

“It is possible that the excessive adverse events in the stenting group could be a reflection of the subset of procedures performed at centers with lower volumes when compared with the centers represented in the CREST [trial],” they write. “In turn, this could suggest that the clinical equipoise of CREST may also be a manifestation of this operator and medical center selection bias that is absent in the real-world setting. In such a view, the results of this study are perhaps better approximations of clinical outcomes the typical patient is likely to experience.”

That suggests, they continue, “that the factors contributing to the clinical equipoise of CREST that are not used in the real-world setting continue to be studied, so as to enhance the safety of this procedure for the US population.”

Limitations Cripple Study Interpretation

But Jay Giri, MD, MPH, of the Hospital of the University of Pennsylvania (Philadelphia, PA), told TCTMD in a telephone interview that the study design prevents any conclusions from being drawn about the comparative effectiveness of stenting vs endarterectomy.

Patients referred for carotid stenting tend to have a higher burden of comorbidities compared with those referred for surgery, he said, and even the best attempts at propensity matching will fail, particularly when administrative data—which lack key clinical information—are used.

The second major problem with the analysis is that it does not account for the enhanced scrutiny to which patients undergoing stenting are subjected, Dr. Giri said. Medicare requires large numbers of patients undergoing stenting to be enrolled in trials or postmarketing studies, a requirement that does not apply to carotid endarterectomy. The more careful follow-up of patients undergoing stenting thus uncovers a greater number of adverse events.

And the final predominant limitation revolves around a finding that is “virtually impossible to believe,” Dr. Giri said, pointing to the similarity of acute MI in the 2 groups. He noted that MI rates were higher with surgery in both SAPPHIRE and CREST, as well as in other trials comparing open surgical procedures with endovascular interventions.

“The comparison as it was done—with an administrative database without even an attempt to compare neurological adjudication rates or at least participation in postmarketing studies—leads to this ‘comparative effectiveness’ analysis being irrevocably flawed,” Dr. Giri concluded.


McDonald RJ, McDonald JS, Therneau TM, et al. Comparative effectiveness of carotid revascularization therapies: evidence from a national hospital discharge database. Stroke. 2014;Epub ahead of print.

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  • Drs. Giri and McDonald report no relevant conflicts of interest.

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