Drug-Eluting Stents Show Promise for Leg Arteries

TUESDAY, March 10 (HealthDay News) -- Treating peripheral arterial disease with drug-eluting stents may save lives and limbs in people with severely obstructed arteries, Greek researchers have found.

Peripheral arterial disease is common in the lower extremities and sometimes leads to severe obstructions, known as critical limb ischemia (CLI), a condition in which the decreased blood flow causes pain and skin ulcers.

"CLI is today a major health problem, especially in Western societies, and is associated with high morbidity and mortality rates," said Dimitris Karnabatidis, the lead researcher and an assistant professor of interventional radiology at Patras University Hospital in Rion, Greece. "More specifically, an estimated 1% of the worldwide population over 50 years old suffers from CLI."

Karnabatidis' study involved 103 people, three-fourths of them diabetics. A normal stent -- a wire mesh tube used to prop open an artery -- was placed in an artery in 41 participants, and 62 were given drug-eluting stents, which were stents coated with sirolimus, an immunosuppressant.

After three years, the researchers found that people with drug-eluting stents had more open arteries (higher primary patency) and less renarrowing (binary restenosis), and they were less likely to need a repeat procedure. People with atherosclerotic disease, or narrowing of the arteries, often must undergo multiple surgical procedures to repair renarrowed arteries at the site of angioplasty or stenting, the researchers said.

"After having such a good experience with drug-eluting stents in the coronary system, there's been enthusiasm about using them in legs," said Dr. Kirk Garratt, director of clinical research at Lenox Hill Heart and Vascular Institute of New York. "We've traditionally used balloons to get these vessels open, but because the vessels get pretty small as you get down below the thigh, the long-term patency rates are not everything you'd dream of."

Because vessels in the leg are either much larger or much smaller than those in the coronary system, the researchers said they were concerned that drug-eluting stents might prove less beneficial as a treatment, but recent studies had shown encouraging results.

"Our main finding was that in the below-the-knee region, sirolimus-eluting have better results than simple stents for CLI treatment in the long term," Karnabatidis said. "Specifically, drug-eluting demonstrated encouraging three-year results compared to simple stents regarding all the predefined angiographic endpoints and the reintervention-free survival clinical endpoint."

The findings were expected to be presented this week at the Society of Interventional Radiology's annual scientific meeting in San Diego.

Also at that meeting, researchers from the John Hopkins School of Medicine were to present a study theorizing that, in the future, adult stem cells can be extracted from a healthy donor's bone marrow and injected into the legs of someone with peripheral arterial disease to grow new blood vessels.

Recent success using luciferase, a bioluminescence imaging agent produced by fireflies, enabled researchers to locate and track stem cells in the body and move this treatment one step closer to reality, they said.

Further research will attempt to verify the feasibility of stem cell therapy for peripheral artery disease and verify the effectiveness of existing therapies using drug-eluting stents.

"Multicenter randomized trials are necessary to support these promising results and build on the level of clinical evidence supporting the integral value of below-the-knee drug-eluting stents in critical limb ischemia treatment," Karnabatidis said.

Garratt added that "the real value of the work being done now is that we're finally getting some experience with stents that are both suited for lower extremity application and can elute drug."

But he added a caution: "Whenever you have a small sample in a single center, you never really know if the findings are going to play out in a bigger trial."

SOURCES: Dimitris Karnabatidis, M.D., Ph.D., assistant professor, interventional radiology, Department of Diagnostic and Interventional Radiology, Patras University Hospital, Rion, Greece; Kirk Garratt, M.D., director, clinical research, Heart and Vascular Institute, Lenox Hill Hospital, New York City; March 10, 2009, presentations, Society of Interventional Radiology annual meeting, San Diego

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