Results presented recently at the Cardiovascular Research Foundation’s (CRF) Annual Transcatheter Cardiovascular Therapeutics (TCT) scientific symposium, in Washington, DC, has shown that cryoplasty, a minimally-invasive treatment that utilizes freezing-cold nitrous oxide injected into an angioplasty balloon, appears to be more effective than standard therapies in the treatment of peripheral artery disease in the lower limbs.
Dr John Laird, Washington Hospital Center, Washington DC, lead investigator of the study, said that blockages that occur in the lower extremities are a challenge to treat, not only because of their location in the body, but because of the extensiveness of the plaque build-up in these arteries.
A total of 102 patients were enrolled in this prospective, multi-centre trial and treated with cryoplasty. Following the initial cryoplasty treatment, long-term clinical follow-up measures indicating the need for revascularization or the presence of continued blockage were collected for two to four years. At nine months, results showed that 82.2% of patients did not need additional treatment and at 16 months, rates were similarly promising at 77.8%. Extended follow up to a mean of 31 months, the clinical patency rate was sustained at a “very favourable” 73.5%.
During cryoplasty, a balloon inserted via catheter into the blocked artery is injected with liquid nitrous oxide, which inflates and cools the balloon in the artery. The cooling and expansion of the balloon causes the plaque clogging the artery to crack when it freezes and is thought to allow for a more uniform opening of the blood vessel compared with standard angioplasty. The cooling also prompts apoptosis, which is a natural occurrence that minimizes the growth of scar tissue, which often occurs with conventional therapies. Cryoplasty potentially inactivates those cells that produce the scar-tissue buildup of restenosis following balloon angioplasty and has reduced the number of patients needing revascularization.
Laird commented, “The early results of cryoplasty in these patients are very promising when compared to the effectiveness of currently available treatments. The fact that overall success rates for these patients have not significantly decreased over time is exciting. Based on these results, long-term follow-up of cryoplasty patients is critically important in order to be able to fully evaluate the durability of cryoplasty for the treatment of lower extremity PAD.”