Two Stents Show Peripheral Artery Efficacy



MIAMI BEACH – Two different self-expandable nitinol stents showed efficacy for treating peripheral arterial stenoses, according to results from two separate, pivotal trials. The Food and Drug Administration is reviewing data from both studies, with the agency’s decisions expected later this year, researchers said at ISET 2012, an international symposium on endovascular therapy.

The EverFlex stent underwent testing in femoropopliteal arteries in 287 patients with peripheral artery disease at 44 centers in the United States and Europe. The trial enrolled patients with Rutherford-Becker clinical categories of 2, 3, or 4, and at least a 50% stenosis. The average age of the patients enrolled was 68 years, two-thirds were men, 43% had diabetes, 88% had hypertension, 40% had Rutherford category 2 disease, and 56% had category 3 disease. The average lesion length was 9 cm, with 29% of patients having a lesion that was 20 cm long.

One of the study’s major goals was testing a single-stent strategy, and 95% of enrolled patients received a single stent, said Dr. Jon S. Matsumura, the trial’s principal investigator. Using single stents for long lesions may reduce the risk of stent fracture.

Dr. Jon S. Matsumura

The primary efficacy end point of DURABILITY II (Safety and Effectiveness Study of EverFlex Stent to Treat Symptomatic Femoral-Popliteal Atherosclerosis) was primary patency in the treated vessel 1 year after stent placement. Study results from 226 patients with follow-up data showed primary patency in 77% after 1 year in an actuarial analysis. This level of success exceeded the 33% performance goal, set on the basis of literature controls using angioplasty interventions, said Dr. Matsumura, professor and chairman of the division of vascular surgery at the University of Wisconsin in Madison.

The study’s primary safety end point was the combined rate of major adverse effects after 30 days. The results showed no such events within that period, with no deaths, no amputations of treated limbs, and no instances of clinically driven target vessel revascularizations.

At 1 year after treatment, a single episode of stent fracture – a class V fracture in the stent’s transaxial spiral configuration – had occurred.

Also at 1 year, 84% of patients had at least a single-level improvement, compared with their baseline Rutherford clinical category, with 65% of patients improving by two or more categories. The researchers collected data on the baseline and 1-year follow-up treadmill walking tests in 29 patients, and 69% of these patients showed improvements in walking distance, with an average increase of about 420 feet per patient.

ORION (A Boston Scientific Trial of the Epic Nitinol Stent in the Treatment of Atherosclerotic Lesions in Iliac Arteries) enrolled 125 patients with a new or restenotic lesion in the common or external iliac artery, or in both, and with a Rutherford-Becker clinical category of 1, 2, 3, or 4. Lesions had to be no longer than 13 cm, with a reference vessel diameter of 5-11 mm. The study enrolled patients at 28 U.S. centers during May 2009–December 2010.

The study population had an average age of 61 years, two-thirds were men, a third of the patients had diabetes, and 76% had hypertension. The average lesion length was just over 3 cm, and the average vessel diameter was just under 8 mm. The operators in the study placed a total of 187 stents into 166 lesions in the enrolled patients.

Dr. Daniel Clair

This study’s primary end point was the combined rate of major adverse events after 9 months of follow-up. These events occurred in four of the 117 patients who were followed for 9 months, a 3.4% rate that consisted entirely of target vessel revascularizations; in three cases, these revascularizations occurred because of stent thrombosis episodes, said Dr. Daniel G. Clair, principal investigator for the study and chairman of vascular surgery at the Cleveland Clinic. The study patients had no other events that made up the major adverse event composite: no deaths within 30 days, no MIs during hospitalization, and no amputations of the index limb during 9 months of follow-up.

The 3.4% observed major adverse event rate ran significantly below the study’s prespecified performance goal of 17%. The 17% goal derived from an expected 8% rate based on the historical literature, plus an added margin of 9%. The actual rate "was much lower than predicted by the literature," based on how iliac artery stents performed in prior studies, Dr. Clair said.

The percentage of patients with a Rutherford-Becker clinical category of 2-4 dropped from 93% at baseline to 18% at 9 months. Average ankle brachial index increased from an average of 0.79 at baseline to 0.97 at 9 months. The primary patency rate at 9 months was 96%.


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