One-Year Results Published for COBRA Study of Boston Scientific's PolarCath Cryoplasty System

October 2, 2012—Subhash Banerjee, MD, et al published results from COBRA, the pilot trial of cryoplasty or conventional balloon postdilation of nitinol stents for revascularization of peripheral arterial segments, in the Journal of the American College of Cardiology (2012;60:1252–1359). Dr. Banerjee, who serves as Principal Investigator of COBRA, first presented the trial data in November 2011 at the annual Transcatheter Cardiovascular Therapeutics scientific symposium in San Francisco.

The COBRA study's purpose is to compare postdilation strategies of nitinol self-expanding stents implanted in the superficial femoral artery of diabetic patients with peripheral arterial disease. The cryoplasty device evaluated in the study is the PolarCath peripheral dilatation system from Boston Scientific Corporation (Natick, MA). The trial was sponsored by North Texas Veterans Healthcare System in Dallas.

As detailed in the Journal of the American College of Cardiology, the investigators conducted a prospective, multicenter, randomized, controlled clinical trial of diabetic patients to investigate whether postdilation of nitinol self-expanding stents in the superficial femoral artery using a cryoplasty balloon reduces restenosis compared to a conventional balloon. Inclusion criteria included diabetes mellitus, symptomatic peripheral arterial disease, and superficial femoral artery lesions requiring implantation of stents > 5 mm in diameter and > 60 mm in length. The study's primary endpoint was binary restenosis at 12 months, defined as a ≥ 2.5-fold increase in peak systolic velocity by duplex ultrasonography.

The investigators reported that 74 patients with 90 stented superficial femoral artery lesions were randomly assigned to postdilation using cryoplasty (n = 45 lesions) or conventional balloons (n = 45 lesions). The mean lesion length was 148 ± 98 mm, the mean stented length was 190 ± 116 mm, the mean stent diameter was 6.1 ± 0.4 mm, and 50% of the lesions were total occlusions.

The investigators found that the postdilation balloon diameters were 5.23 ± 0.51 mm versus 5.51 ± 0.72 mm in the cryoplasty and conventional balloon angioplasty groups, respectively (P = .02). At 12 months, binary restenosis was significantly lower in the cryoplasty group (29.3% vs 55.8%; P = .01; odds ratio, 0.36; 95% confidence interval, 0.15–0.89).

Among diabetic patients undergoing implantation of nitinol self-expanding stents in the superficial femoral artery, postdilation with the cryoplasty balloon reduced binary restenosis compared to conventional balloon angioplasty, concluded the investigators in the Journal of the American College of Cardiology.