NEW YORK — The COBRA trial suggests that cryoplasty for post-dilation of nitinol stents in the superficial femoral artery is an effective adjunctive treatment for peripheral arterial disease (PAD) in diabetics.
“Post-dilation of SFA stents with cryoplasty can significantly reduce the risk of restenosis in patients with diabetes mellitus,” the study concludes. The authors note that post-dilation using cryoplasty significantly reduced the in-stent restenosis rates at one year, compared with post-dilation using a conventional balloon.
Results from the COBRA (Polar Cath Cryoplasty Versus Conventional Balloon Postdilation of Nitinol Stents for Peripheral Vascular Interventions) trial, led by Subhash Banerjee, MD, FACC, FSCAI, chief of cardiology at the VA North Texas Health Care System in Bonham, appeared recently in the Journal of the American College of Cardiology.1
The authors explain that cryoplasty is performed with a U.S. FDA-approved angioplasty balloon positioned at the arterial lesion and inflated with nitrous oxide, which cools the surface of the balloon and freezes the plaque in the artery.
“This action has three potential beneficial effects: 1) weakens plaque, thereby promoting uniform dilation resulting in less vessel trauma; 2) reduces vessel wall recoil; and 3) induces smooth muscle cell apoptosis, limiting neointima formation,” they write.
In the multicenter randomized trial comparing cryoplasty with conventional balloon post-dilation of nitinol self-expanding stents implanted in the SFA of 74 diabetic patients with symptomatic PAD, 90 lesions were stented, half of them total occlusions.
Post-dilation balloon diameters were 5.23 mm with conventional balloon angioplasty, placed in half of the trial participants, compared with 5.51 mm with cryoplasty, performed in the other half.
Although five patients died during the 12-month follow-up period, none of the deaths was related to the index procedure, and the mortality rate was not significantly different between study arms (p=0.31).
Binary restenosis — the primary outcome, defined as at least a 2.5-fold increase in peak systolic velocity within the stented segment — was significantly lower in the cryoplasty group (29.3% vs 55.8%, p=0.01; odds ratio 0.36).
There also was a sustained improvement at 12 months in the ankle-brachial index in the cryoplasty group as opposed to the conventional balloon angioplasty group.
1. Banerjee S, Das TS, Abu-Fadel MS, Dippel EJ, et. al. “Pilot Trial of Cryoplasty or Conventional Balloon Post-Dilation of Nitinol Stents for Revascularization of Peripheral Arterial Segments: The COBRA Trial.” J Am Coll Cardiol. 2012 Sep 5. [Epub ahead of print] PubMed PMID: 22981558.