What is the evidence for the efficacy of cryoplasty?

Cryoplasty is a technique for treating vascular stenosis which combines balloon angioplasty with cold injury. The combination is proposed to reduce the incidence of restenosis by inhibition of neointimal hyperplasia. There have been several clinical studies which purport to show improved patency compared to conventional angioplasty. Unfortunately, these are not comparative or controlled studies and have not been performed, analyzed or reported in accordance with recognized reporting standards for peripheral vascular intervention. The studies on femoropopliteal disease have selected favourable patients. Of greatest concern is the use of surrogate endpoints in lieu of objective demonstration of vessel patency. Critical interpretation of the results fails to demonstrate any convincing superiority of cryoplasty compared to conventional balloon angioplasty. Where little difference in outcome exists between two techniques, a trial comparing them will require hundreds of patients to be sufficiently powered to demonstrate a benefit of one technique over the other. As cryoplasty is significantly more expensive than conventional angioplasty, the cost benefit ratio is unfavourable and such a trial is unlikely to occur. This article is a critical review of the technique of cryoplasty. The reader will be able to: describe expected outcomes from balloon angioplasty; describe the theoretical role for cold injury as a component of angioplasty; recognize the need to adhere to well defined standards when reporting the results of new techniques for treating vascular disease; critically review the results of cryoplasty; understand the limitations and relevance of the published clinical results of cryoplasty.