FDA OKs Device to Open Blocked Carotid Arteries

The U.S. Food and Drug Administration (FDA) recently cleared for marketing the Enroute Transcarotid Neuroprotection System (Enroute TPS), for use during a minimally invasive procedure to restore normal blood flow to narrowed carotid arteries. It is the first device designed to access the carotid arteries through an incision in the neck, instead of the groin, and uses a blood flow reversal system to capture pieces of the blockage dislodged during the procedure.

The Enroute TPS is manufactured by Silk Road Medical Inc. of Sunnyvale, Calif.

The carotid arteries are two large blood vessels on either side of the neck that supply oxygenated blood to the brain. Cholesterol or fatty substances can narrow one or both of the carotid arteries, causing carotid artery disease. If a piece of plaque breaks off, it can travel to arteries in the brain and cut off blood flow, resulting in a stroke. According to the National Heart Lung and Blood Institute, more than half of the strokes occurring in the United States each year are caused by carotid artery disease. A person with the disease may not experience any signs or symptoms until a stroke occurs.

A severe narrowing or blockage of the carotid artery may require a physician to perform a minimally invasive balloon angioplasty procedure in which a balloon on a long flexible tube called a catheter is threaded through a patient’s vasculature from the groin to the site of the blockage, inflated to open the artery and then a small mesh tube called a stent is placed at the site to keep the artery open.

The device allows physicians to insert a catheter into the artery in the neck above the narrowed or blocked section of the artery rather than having to enter through the groin. During the stenting procedure, physicians typically use a filter or additional balloon to capture and remove small pieces of debris that might be dislodged and potentially travel to the brain.

“The Enroute technology enables a true hybrid procedure offering the best of both worlds—the critical protection against peri-procedural stroke we’ve achieved with carotid endarterectomy (CEA) with the ability to reduce surgical complications using minimally invasive endovascular techniques (CAS),” said Manish Mehta, M.D., professor of surgery at Albany Medical College and an Investigator in the ROADSTER trial. “It is also a quick, efficient procedure which can be performed under local anesthesia with minimal scarring, which is highly beneficial for both the patient and the operator.”

Richard Cambria, M.D., chief of the Division of Vascular and Endovascular Surgery at Massachusetts General Hospital and the national co-principal investigator of the ROADSTER trial along with colleague Christopher Kwolek, M.D., said, “We continue to operate on high surgical risk patients because transfemoral CAS has shown excess peri-procedural stroke risk. With the Enroute Transcarotid NPS, we now have CEA-like neuroprotection and a simplified procedure that can fulfill the promise of CAS.”

The FDA cleared the Enroute Transcarotid NPS based in part on results of the ROADSTER trial, which achieved a 30-day stroke rate of 1.4 percent  in the pivotal cohort, the lowest to date for any prospective trial of CAS. There were no major strokes and there were no strokes in important high-risk subgroups, including the elderly (age 75 or older), women, and symptomatic patients.

The Enroute TPS captures debris by temporarily shunting blood flowing through the narrowed section of the artery away from the brain and into a filtering system outside the body. Blood is then returned to the body though a vein in the leg. Because the carotid artery branches into many interconnected smaller arteries, the brain still receives oxygenated blood during the procedure.

“Until today’s clearance, the only FDA-cleared systems to capture and remove debris and prevent them from reaching the brain during carotid angioplasty and stenting procedures required entry into the body through the femoral artery using an incision in the groin,” said William Maisel, M.D., acting director of the Office of Device Evaluation at the FDA’s Center for Device and Radiological Health. “The Enroute TPS provides a minimally invasive treatment for certain patients whose tortuous (twisted) or diseased vasculature does not permit access via the groin for treating their narrowed carotid arteries.”

The FDA reviewed the data for the Enroute TPS through a 510(k) submission, a regulatory pathway for low-to-moderate risk medical devices that are substantially equivalent to a legally marketed predicate device that is not subject to premarket approval. In this case, the FDA found the Enroute TPS to be substantially equivalent to a flow reversal system currently on the market that uses similar technology and has the same intended use but is designed to be introduced into the patient through the blood vessels in the groin.

The trial showed the rate of stroke, heart attack, and death among the Enroute TPS patients was 3.5 percent, significantly lower than the study performance goal of 11 percent. At least one serious adverse event occurred in 14.2 percent of patients, including excessive bleeding or injury at the device access site, low blood pressure due to the device or procedure, and blood clot formation within the placed stent. These events are consistent with the type and rate of serious adverse events associated with other carotid artery procedures.

“Clearance of the Enroute Transcarotid NPS is a result of the dedication of the ROADSTER investigators to their patients, the highly collaborative interaction with our colleagues at the FDA, and the hard work of our employees,” said Ric Ruedy, Silk Road’s executive vice president for clinical, regulatory and quality.

Silk Road Medical also has submitted a premarket approval application for the Enroute Transcarotid Stent System, which is an optimized stent delivery system designed for use with the Enroute Transcarotid NPS.

“With clearance of the Enroute Transcarotid NPS in hand, we are on the eve of commercialization in the United States. Severe carotid artery stenosis is one of the last frontiers in vascular disease that is still treated primarily by an open surgical approach. We look forward to bringing our less-invasive, surgically inspired Enroute systems to market for vascular specialists and their patients,” said Erica Rogers, CEO.

Silk Road Medical is a private company that develops and manufactures less-invasive medical devices intended to improve the treatment of intra- and extra-cranial cerebrovascular disease through proprietary transcarotid therapies.