Micrus Endovascular (San Jose, California) said yesterday that the FDA has conditionally approved the firm's Vitesse Intracranial Stent Study for Ischemic Therapy (VISSIT) clinical trial application.

The Pharos Vitesse intracranial stent is Micrus' second balloon-expandable stent for the treatment of intracranial ischemic stenosis. The company says it is in the process of initiating study sites in the U.S., Europe and China.

The investigational device exemption (IDE) study will compare outcomes between patients treated with the stent and another medical therapy, Micrus said.

"We are pleased to obtain IDE approval for VISSIT and proud to support the first global, industry-sponsored prospective, randomized clinical trial to evaluate the safety and effectiveness of an intracranial stent for this significant medical condition," said John Kilcoyne, CEO/chairman of Micrus Endovascular. "Our second-generation Pharos Vitesse stent is designed with a series of technical advances for improved handling and navigability and also incorporates a proprietary coating that we believe may reduce the need for retreatment due to restenosis."

Bob Stern, president/COO of Micrus, told Medical Device Daily the study will enroll 250 patients with 125 in each arm, and will be split geographically between the U.S., Europe, and China. Post-discharge follow-up will be at 30 days, six months and 12 months, he said.

Stern said it is too early to predict when the device will be available in the U.S. and whether the company will seek a humanitarian device exemption (HDE) or a premarket application approval.

The Pharos Vitesse is manufactured exclusively for Micrus Endovascular through a collaborative agreement with Biotronik (Berlin). According to the company, it enables the intracranial delivery and deployment of a stent in one step, eliminating the need for pre-dilation of constricted vasculature.

"The other devices on the market universally are self-expanding stents," Stern said.

Pointing to the coronary stent market, Stern said interventional cardiologists stopped using self-expanding stents about 10 years ago because of problems with migration and restenosis. With those stents, he said, the physician has to go in and pre-dilate with a balloon, deliver the stent, and then often times they have to post-dilate as well.

"With ours it's a rapid-exchange, fast-delivery platform. You just go in and deliver the stent," Stern said. "Procedure time is going to be a log quicker in most cases because you're only delivering the stent, not delivering the balloon and then the stent and then the balloon again."

One company with a self-expanding stent aimed at treating atherosclerotic lesions, or accumulated plaque in brain arteries, is Boston Scientific (Natick, Massachusetts), which earned a humanitarian device exemption from FDA in 2005 for its Wingspan stent, used along with its Gateway balloon catheter (Medical Device Daily, Aug. 10, 2005). The Wingspan is a self-expanding, nitinol stent sheathed in a delivery system that enables it to reach and open narrowed arteries in the brain.

Stern also noted that the Pharos Vitesse has a CE mark in Europe for two indications, ischemic disease and for the treatment of wide-neck aneurysms. That's important, he said, because it is the only stent approved for multiple use.

"It's just very promising to have another weapon in our arsenal for the ischemic market," Gordon Sangster, CFO, told MDD.

Micrus develops implantable and disposable devices for use in the treatment of cerebral vascular diseases. The company says its product line enables physicians to gain access to the brain in a minimally invasive manner through the vessels of the circulatory system. Its three-dimensional microcoils are designed to automatically deploy within the aneurysm, forming a scaffold that conforms to a wide diversity of aneurysm shapes and sizes. Micrus also sells accessory devices and products used in conjunction with its microcoils.