Dr William Gray

Presenting the results of the Carotid RX ACCULINK/RX ACCUNET Post-Approval Trial to Uncover Unanticipated or Rare Events (CAPTURE), investigators reported that in 2500 high-risk symptomatic and asymptomatic patients, the 30-day event rate, a combined end point of death, stroke, or MI, was 5.7%, significantly lower than the 8.3% observed in the ACCULINK for Revascularization of Carotids in High-Risk Patients (ARCHER) trial.

"The conclusions from this trial are that we were able to transfer the technology successfully and achieve better outcomes than a pivotal trial that preceded it," said lead investigator Dr William Gray (Columbia University Medical Center, New York, NY) during a media briefing here at the American College of Cardiology 2006 Scientific Sessions.

The CAPTURE trial is an observational study required by the Food and Drug Administration following the market approval of Guidant's RX ACCULINK carotid stent system and RX ACCUNET distal-protection system. In addition to evaluating the transition of the device into clinical practice, Gray said the registry data would help determine whether there are any unanticipated device malfunctions not observed in clinical trials. To ensure a broad distribution, no single hospital included in the registry was allowed to perform more than 40 implantations and no more than one third of patients were enrolled at hospitals with high levels of experience.

Compared with the ARCHER study, the patients in the registry were older and included more women. In addition, patients had more hypertension, hypercholesterolemia, and renal failure. Despite these differences, the overall 30-day death/stroke/MI event rate was significantly lower than the event rate observed in ARCHER. In terms of individual end points, MI was significantly lower among patients in the registry, while there was only a trend toward reduced death and stroke.

"Operators across the board are getting better at doing what we're doing," Gray told heartwire. "We started these trials in 2001, and we didn't know what patients we should be treating and what patients were at risk, in terms of what we were offering them, and how these procedures might or might not help. I think we have a better handle on that now."

Regarding the experience of physicians in the CAPTURE registry, investigators categorized operators into three categories: those who implanted at least five carotid stents with the ACCULINK/ACCUNET system and who had experience with carotid stenting; those with carotid stenting experience (>10 cases) but no experience with the ACCULINK/ACCUNET system; and those experienced with carotid angiography and rapid exchange systems but with no carotid stenting experience.

"There were no differences across any of these three strata in any of the categories that we looked at, whether it was stroke, death, or MI, individually or as a combination end point," said Gray. "It was pretty impressive."

Overall, the filter basket detached in 0.2% of all cases, but after a modification to the system, there were no additional reported device failures.

During the late-breaking clinical-trials session, moderators noted that the data appear to run counter to other angioplasty and stenting registries that show experience and volume as important predictors of success. Dr William O'Neill (Beaumont Hospital, Royal Oak, MI) said that separating the physicians into those considered low-volume and high-volume operators would likely have yielded a significant difference. However, as Gray noted, the experienced operators had previously used the ACCULINK system. He added that the CAPTURE investigators plan to study the learning curve with the system, looking specifically at outcomes of the first five to 10 cases operators perform.

The CAPTURE registry also included more asymptomatic patients than were included in the ARCHER trial. While the FDA has approved the device for high-risk symptomatic and asymptomatic patients, the Centers for Medicare and Medicaid Services (CMS) reimburses clinicians only for treating symptomatic patients.

Among the 2267 patients in CAPTURE who were asymptomatic, the 30-day combined end point of death/stroke/MI was 4.9%. Most important, the combined 30-day stroke and mortality event rate was 4.4% and the 30-day stroke event rate was 3.5%. Gray said the stroke/death rate for asymptomatic patients approaches the Asymptomatic Carotid Atherosclerosis Study (ACAS) and Asymptomatic Carotid Surgery Trial (ACST) endarterectomy outcomes observed in high-risk patients and octogenarians. Guidant plans to approach the CMS with these data to seek reimbursement for carotid stenting in these asymptomatic patients, said Gray.

Bigger trials with normal-risk asymptomatic patients are also currently under way. The Carotid Revascularization vs Stenting Trial (CREST), a head-to-head comparison of the efficacy of endarterectomy vs stenting in the prevention of stroke over a follow-up period of up to four years, is currently in progress. Gray said more than 70 sites are participating and approximately 900 patients have been enrolled. Another trial, sponsored by Abbott, is also ongoing.

Gray noted that octogenarians still don't fare very well with carotid stenting, with a 30-day end point of death/stroke/MI of 8.2% and a 30-day stroke rate of 6.6%. "We all recognize the risk of stroke or death in these patients over the age of 80 and that it needs to be improved on," he said.