Pilot trial of cryoplasty or conventional balloon post-dilation of nitinol stents for revascularization of peripheral arterial segments: The COBRA trial

Objectives: The purpose of this study is to compare post-dilation strategies of nitinol self-expanding stents implanted in the superficial femoral artery of diabetic patients with peripheral arterial disease. Background: Endovascular treatment of superficial femoral artery disease with nitinol self-expanding stents is associated with high rates of in-stent restenosis in patients with diabetes mellitus. Methods: We conducted a prospective, multicenter, randomized, controlled clinical trial of diabetic patients to investigate whether post-dilation of superficial femoral artery nitinol self-expanding stents 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. Primary endpoint was binary restenosis at 12 months, defined as <2.5-fold increase in peak systolic velocity by duplex ultrasonography. Results: Seventy-four patients, with 90 stented superficial femoral artery lesions, were randomly assigned to post-dilation using cryoplasty (n = 45 lesions) or conventional balloons (n = 45 lesions). Mean lesion length was 148 ± 98 mm, mean stented length was 190 ± 116 mm, mean stent diameter was 6.1 ± 0.4 mm, and 50% of the lesions were total occlusions. Post-dilation balloon diameters were 5.23 ± 0.51 mm versus 5.51 ± 0.72 mm in the cryoplasty and conventional balloon angioplasty groups, respectively (p = 0.02). At 12 months, binary restenosis was significantly lower in the cryoplasty group (29.3% vs. 55.8%, p = 0.01; odds ratio: 0.36, 95% confidence interval: 0.15 to 0.89). Conclusions: Among diabetic patients undergoing implantation of nitinol self-expanding stents in the superficial femoral artery, post-dilation with cryoplasty balloon reduced binary restenosis compared to conventional balloon angioplasty. (Study Comparing Two Methods of Expanding Stents Placed in Legs of Diabetics With Peripheral Vascular Disease [COBRA]; NCT00827853)