Cook stent could prevent more amputations, study finds

A drug-coated stent from Indiana-based Cook Medical, the maker of devices for minimally invasive medical procedures, was more effective than standard therapy for patients with blockages in an upper-leg artery, a study found.

With the Cook stent, patients’ arteries reclogged in 17 percent of patients after one year compared with 33 percent of those who underwent treatment with an artery-clearing procedure known as angioplasty and an older type of stent, according to the one-year study presented Monday at the Transcatheter Cardiovascular Therapeutics meeting in Washington, D.C.

The Cook device would be the first drug-coated stent approved in the U.S. as an alternative to bypass surgery for treatment of peripheral arterial disease, a condition affecting about 12 million Americans, according to the National Institutes of Health. Closely held Cook, based in Bloomington, has filed for U.S. approval of the stent and will face competition in the $3.4 billion market from Abbott Park, Ill.-based Abbott Laboratories and Minneapolis-based Medtronic Inc.

The device received European approval earlier this year.

“This is an important step toward reducing amputations, bypass and repeat intervention in patients with peripheral artery disease, which is very difficult to treat,” said Michael Dake, a surgeon at Stanford University Medical Center in Palo Alto, Calif., and the study’s principal investigator, in a statement.

Peripheral arterial disease occurs when plaque clogs arteries and disrupts blood flow to the legs and other parts of the body. Patients often have cramps and tiredness in the legs or hips when walking. They have more than four times the risk of heart attack and stroke and untreated conditions can lead to leg amputations, according to the American Heart Association.

Cook funded the study, which also compared use of its device with a bare-metal stent alone. By that measure, 10 percent of patients with the Cook device had a renarrowing of their arteries that blocked blood flow compared with 27 percent treated with a bare-metal stent, according to the study.

“We wanted to see if we can come up with a more durable procedure that will last longer” for restoring blood flow to the legs, Sanjay Misra, an interventional radiologist at the Mayo Clinic in Rochester, Minn., and an investigator in the study, said in a Sept. 16 telephone interview.

The market for peripheral artery disease products is projected to grow 15 percent to $3.9 billion this year from $3.4 billion in 2009, said Teri Minor, a senior analyst with Frost & Sullivan’s in San Antonio, in a Sept. 17 telephone interview.

‘New Era’

The 479-patient study is the first to test drug-coated stents to clear blockages in the largest artery of the upper leg and a successful outcome may “usher in a new era” for treatment of the disease, said Gregg Stone, director of cardiology at Columbia University Medical Center in New York, in a Sept. 14 telephone interview.

The use of stents coated with drugs to prevent the build-up of scar tissue has become commonplace in heart surgery, and the study looked at how effective such stents would be when used in the leg, Dake said in a Sept. 16 telephone interview.

The most common treatment for clots in the leg is a procedure known as balloon angioplasty, which inserts a tiny balloon to clear the clogged vessel. In some cases the angioplasty is followed by placing bare-metal stents, which are not coated with drugs, to hold open the artery in patients.

The bare-metal stents have been prone to fracture when placed in the leg because of repeated movement and the stress of walking, Misra said.

Zilver PTX

The Cook stent, called Zilver PTX and already sold in Europe, does not include a layer of chemical polymers, commonly used on drug-coated stents, to hold the medicine in place so it can be released gradually. When used for heart stents, the polymers may inhibit proper healing and cause long-term side effects.

“If you could do without the polymer, that takes one less thing out of the equation that could have a negative effect,” Dake said.

Cook filed for U.S. approval for its Zilver PTX stent in June for use in treating blockages in the femoral artery, a large blood-carrying vessel that runs from the lower groin to the thigh.

Abbott and Medronic either market or are testing stents and inflatable-drug coated balloons for treatment of clogged leg arteries.

“The market is pretty attractive right now,” said Jan Wald, an analyst with Noble Financial Group, in a Sept. 17 telephone interview. “We’re starting to see companies spend more time and focus more on this.”