XCELL finds infrapopliteal nitinol stenting safe, effective for CLI

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Infrapopliteal nitinol stenting is safe and effective for treating critical limb ischemia (CLI), according to results from the XCELL trial. Researchers reported improved outcomes at six and 12 months in Rutherford Class 4-6 patients, but added that further studies based on larger patient groups and longer follow-up were needed.

Their results were published online July 24 in Catheterization and Cardiovascular Interventions.

While percutaneous transluminal angioplasty with stent deployment of infrapopliteal arteries is an accepted practice, it has yet to be a proven therapy for patients with CLI, wrote Krishna J. Rocha-Singh, MD, of the Prairie Education & Research Cooperative in Springfield, Ill., and colleagues. The XCELL (Xpert Nitinol Stenting for Clinically IschEmic Lower Limbs) trial was designed to evaluate the safety and effectiveness of the Xpert self-expanding nitinol stent (Abbott Vascular) in Rutherford Class 4-6 patients.

The single-arm nonrandomized study enrolled 120 patients with CLI lesions between 4 cm and 15 cm who underwent primary infrapopliteal nitinol stent deployment between July 2006 and April 2009. To be included, patients needed to have documented chronic critical limb ischemia and wound care more than two weeks before enrollment.

The primary endpoint was 12-month amputation-free survival, which they defined as freedom from all-cause death or unplanned amputation of the target limb. Secondary endpoints included freedom from major amputation, improvement in the ankle/brachial index and the toe/brachial index, stent patency, stent fracture rates and six- and 12-month wound healing rates and self-reported pain relief assessments. An independent core lab conducted the stent patency analyses.

“The XCELL trial is, to date, the largest prospective, multicenter, core laboratory-adjudicated study evaluating the safety and effectiveness of a bare metal self-expanding stent for infrapopliteal interventions in CLI patients,” wrote Rocha-Singh and colleagues. The authors added that they selected protocol-mandated safety and effectiveness endpoints for the evaluation as well as “often neglected” patient-centric outcomes such as limb preservation and wound healing.

The rates of death, MI, cerebrovascular accident and major amputation were 0.8 percent, 0 percent, 0.8 percent and 1.7 percent, respectively. They described the rate of target lesion revascularization (TLR) as low, at 29 percent despite a six-month binary restenosis rate of 68.5 percent.

The overall 12-month rate of amputation-free survival was 78.3 percent. Stratified by baseline Rutherford Class, amputation-free survival was 100 percent, 77.3 percent and 55.2 percent for classes 4, 5 and 6, respectively. Overall survival and limb salvage were 87.5 percent and 89.6 percent, respectively.

At 12 months, 62.5 percent of wounds that could be analyzed had healed completely, a healing rate comparable to open surgery, they observed.

“The deployment of the Xpert nitinol stent was successful in 100 percent of the lesions, with a 30-day adverse event rate of 6.7 percent, despite the fact that 30 percent of the lesions were chronic total occlusions,” they wrote. “At 12-month follow-up, the overall cumulative rate of adverse events increased to 63.3 percent, largely driven by the increased rate of TLR to maintain vessel patency.”

In a statement, Rocha-Singh said the study findings confirm that infrapopliteal nitinal stenting is safe and effective. “While there were a few major adverse events, such as death, heart attack, or major amputation that occurred in the first 30 days, at the first year post-procedure, limb preservation, wound healing and pain relief rates were excellent," he said.

The XCELL trial is not a randomized controlled clinical trial, the authors emphasized, and results can’t be compared to such trials. The study’s rate of loss to follow-up was 16.7 percent, which could impact the study’s conclusions.

They noted that the study had a relatively short-term follow-up, but added that most adverse limb events occurred with the first six months. They also highlighted the use of sicker patients in their trial, with 82.5 percent in Rutherford Class 5 and 6. They recommended further studies enrolling more patients and a longer-term follow-up was needed.

The study was sponsored through a grant from Abbott Vascular.