Operator Learning Curve Important in CAS vs. CEA Outcomes

SAN FRANCISCO, CALIF.—To further understand the differences in outcomes of carotid artery stenting (CAS) and carotid endarterectomy (CEA), trial design elements, as well as operator learning curve, should be taken into account, according to two trial review presentations at TCT 2011.

The main CREST study randomized 2,502 patients with symptomatic or asymptomatic disease to CAS or CEA. Overall, there was no difference in the estimated 4-year rates of the primary endpoint (composite of periprocedural stroke, MI, or death, or the incidence of ipsilateral stroke ≤ 4 years) between the 2 groups. However, there was a higher risk of minor stroke with stenting and a higher risk of MI and cranial nerve palsy with surgery.

The US Food and Drug Administration (FDA) has already voted that CAS is both safe and effective and that the benefits of the procedure outweigh the risks. In his presentation of the FDA’s analysis of CREST, Peter A. Schneider, MD, of Kaiser Permanente, Honolulu, Hawaii, said that although he is a “believer” in CEA, “carotid stenting is here to stay.”

“We have two really good treatments that both meet the thresholds,” he said. “The difference between the stenting patients and the endarterectomy patients that have minor strokes when you add up the numbers is actually a fairly similar rate of overall neurological mayhem.”

Looking back on CAS trials, Schneider acknowledged significant improvements in outcomes over the past decade.

“We know that there is a bit of a learning curve that has occurred over the past number of years,” he said. “We’re not sure exactly what we’re learning, but we know we’re getting better at this. It will be very interesting to sort out what the different reasons are for this improved result.”

Although the observed reduction in CAS-related deaths could be attributed to the routine performance of CAS on more patients at each individual institution, Schneider said that understanding the precise reasons for improvement could be vital to the improvement of clinical practice.

“Imagine a future where you can customize the devices, where you have cerebral protection that’s particularly associated with the benefits in that particular anatomy or that particular symptom,” he said.

Trial design is key

Explaining the differences in European and US CAS trial design, William A. Gray, MD, of New York-Presbyterian Hospital, New York, said that the stringent CAS operator requirements imposed in CREST, with less than 50% applicants admitted to the trial, “bought time” for technique, operator experience and patient selection to be improved enough to balance outcomes between CAS and CEA.

Learning Curve DrsHe said that the operators sought for CREST had to have “unconscious competence,” meaning that they had enough experience to not overthink what they were doing during a procedure.

Comparing four US and European trials, Gray analyzed embolic protection use in each, with CREST utilizing it in almost all patients. “There are no randomized data that say that using embolic protection is better than not using embolic protection,” he said. “However, a meta-analysis confirmed utility of [embolic protection devices] in lowering rates of complication.”

As MI was a primary endpoint only in CREST, Gray said that although it is important to prevent stroke, “myocardial infarction is an important price to pay” in doing so.

Ultimately “trialists are obligated to make ethical choices for their investigators and patients,” Gray said. “If those safety assurances aren’t made, then you can’t offer [a procedure] ethically to a patient.”

Summing up both presentations, panelist L. Nelson Hopkins, MD, of Millard Fillmore Gates Hospital, Buffalo, New York, credited each new trial with providing a piece of the full puzzle that will enable clinicians to ultimately best determine when to appropriately use each procedure.

“Each trial teaches us a little something,” he said. “No trial has all the answers, and we’re getting to the point where carotid stenting is getting more straightforward. If you pick the right patients, it’s really a simple procedure.”

Disclosures
  • Dr. Gray reports financial relationships with multiple companies.
  • Dr. Schneider reports receiving grant or research support from Abbott Vascular and Cordis, consulting fees or honoraria from Abbott Vascular, Gore and Medtronic, and royalty income from Cook.

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