Medical Device Daily Associate

Abbott Laboratories (Abbott Park, Illinois) said it would begin the first trial of its kind to assess the benefits of using stents in the neck arteries of likely stroke patients who have not shown symptoms of the disease. Stroke is the third- leading cause of death in the U.S.

If results of the new trial, dubbed ACT I — for Carotid Angioplasty and Stenting vs. Endarterectomy in Asymptomatic Patients with Significant Extracranial Carotid Occlusive Disease Trial — are successful, asymptomatic patients who normally would have surgery could have the alternative of a minimally invasive carotid stenting procedure.

The trial will compare stenting to surgery in the carotid arteries of such patients who normally would be referred for surgery for carotid artery disease (CAD). About one-fourth of all strokes are caused by CAD.

Abbott, via its Abbott Vascular Devices (Redwood City, California) division, is currently awaiting U.S. regulatory approval for a carotid stent for high-risk patients for whom surgery is not recommended and expects a decision in 2Q05. That approval is for the same system being used in the ACT I trial, the Xact carotid stent system coupled with the Emboshield embolic protection system

Physicians use these minimally invasive devices to treat carotid artery disease by placing a stent in the carotid artery to restore unrestrained blood flow to the brain. The stent is brought into position in the carotid artery via thin catheters that are threaded through the vascular system from a small access site — typically made in the femoral artery in the groin. A special device called an embolic protection filter is opened up like an umbrella downstream from the stenting procedure to protect the patient's brain by catching emboli (plaque) that may be dislodged during the procedure.

The first trial of its kind, this multi-center, randomized trial will compare carotid artery stenting (CAS) to carotid artery surgery — also called carotid endarterectomy or CEA, the current “gold standard“ of treatment in asymptomatic patients along with medication and lifestyle modification.

Like coronary arteries, the carotid arteries (located on each side of the neck and the primary suppliers of blood to the brain) can become clogged from plaque deposits, which can lead to stroke. Abbott recently received conditional approval for this study from the FDA.

Carotid artery stent systems have not yet been FDA-approved for use in asymptomatic patients healthy enough to undergo surgery (who comprise about 75% of patients at risk for stroke) due to lack of clinical data.

If the new trial, which will involve about 1,500 patients, shows carotid stents to be as effective as traditional surgery in preventing stroke in lower-risk patients, it would significantly expand the market for the procedure.

Currently, the Centers for Medicare & Medicaid Services (CMS; Baltimore) provides reimbursement for carotid stents in high-risk patients with stroke symptoms who are not good candidates for surgery, a potential patient population of roughly 15,000.

If Abbott's new trial is successful, it could potentially expand coverage for the procedure to an additional population of close to 70,000 patients.

And the potential market could ultimately be even higher. An estimated 175,000 CEAs were performed in the U.S. in 2003, with another 100,000 procedures done in other countries.

Ken Rosenfield, MD, director of cardiac invasive services at Massachusetts General Hospital (Boston) and co-principal investigator of ACT I, said, “ACT I is designed to assess the benefits of carotid stenting for those patients at risk of stroke for whom surgery and/or medication remain the only options. This is truly a landmark study that should have an immediate, positive impact on patients' lives.“

Abbott is one of many companies competing in this very promising space in both the U.S. and abroad. Other companies developing distal protection devices and carotid stents include Cordis Endovascular (Warren, New Jersey), whose carotid artery stent system is comprised of the Nitinol Self-Expanding Stent and the Angioguard Emboli Capture Guidewire; Boston Scientific (Natick, Massachusetts), with the FilterWire EZ and Carotid Wallstent; the NexStent from EndoTex Interventional Systems (Cupertino, California), now under evaluation in the CABERNET trial; Medtronic (Minneapolis) with the PercuSurge balloon occlusion system; the Vascular Systems unit of B. Braun Medical (Melsungen, Germany) and Rubicon Medical (Salt Lake City), with the Rubicon Filter.

Asked how his company intends to compete with such stiff competition, Jonathon Hamilton, manager of external communications for Abbott, told Medical Device Daily that his company's system was the only one specifically designed for carotid stenting. “Some of our competitors have taken products, stents and the like that were developed for coronary applications or saphenous vein graft applications and just applied it to the carotid.“

He also said that the embolic protection device is a differentiator. “On Abbott's device, when that embolic protection device is open and if the wire that it sits on inadvertently moves, in Abbott's case, the embolic protection device will just sit in place,“ unlike many other such systems that he said are fixed to the wire.

According to the company, the Emboshield is the only filter that moves freely on a wire, the Barewire, and physicians can select from a range of Barewires for use in different anatomies and procedures. Barewire technology is designed to more closely resemble the guide wires to which physicians are accustomed when performing interventional procedures. This similarity to current practice is intended to provide optimal deliverability and to make Emboshield easier to use.

Abbott has an exclusive agreement with MedNova (Galway, Ireland) to distribute the EmboShield filter and Xact carotid stent products.

The ACT I trial was designed to establish the non-inferiority of CAS to CEA in this patient population. According to Hamilton, the trial, which will involve roughly 50 hospitals in the U.S., will enroll at a roughly 3-to-1 ratio of CAS to CEA. The trial's primary endpoints will be 30-day major adverse event (MAE) rates combining stroke, death and myocardial infarction and ipsilateral strokes between 31 and 365 days. The trial's secondary endpoints include target lesion revascularization rate, device/procedural success rates, cumulative composite morbidity (nerve damage, wound complications, general anesthetic complications, etc.), and long-term ipsilateral stroke rates through five years of follow-up.

In addition to comparing clinical impacts, Hamilton noted that ACT I will assess the relative economic and quality of life factors associated with CAS and CEA.

He said the trial would quantify not only device and facility costs, but also the total costs to the healthcare system of each treatment option.

Such information should help to support informed decision-making in procedural reimbursement and treatment selection. This information, he noted, is especially important, given that stroke is the leading cause of inpatient Medicare expenses for long-term care.

“Precisely for that reason, we're going out and we're going to collect the data that CMS and other healthcare providers will want so that they can see what the cost benefit is to doing this kind of a study.“

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