Cryoplasty for peripheral vascular disease

Peripheral arterial disease results from narrowing or blocking of the main arteries to the legs, usually due to atherosclerosis. The resulting reduction of blood flow caused by a blocked or narrowed artery can either cause pain on walking or become so severe that loss of the leg is threatened. Endovascular surgery involves inserting a small balloon through a needle puncture into the affected artery. The balloon is then inflated to stretch the artery open (called percutaneous balloon angioplasty). Unfortunately the artery often narrows again over time, which is called restenosis. Cryoplasty cools the vessel wall at the same time as doing the balloon angioplasty and may reduce thickening of the inner muscular layer of the blood vessel to improve long-term angioplasty results and prevent restenosis. 

The benefit of cryoplasty over conventional balloon angioplasty has yet to be definitely established as there are few randomised controlled trials evaluating this method. The technical success rates and rates of unobstructed arteries (primary patency) compared with conventional angioplasty seen in seven trials (478 patients) were inconsistent. Long-term outcomes, in particular, are as yet to be assessed fully. Currently there are insufficient data to support the routine use of cryoplasty over conventional balloon angioplasty in the treatment of peripheral arterial disease.

Authors' conclusions: 

The benefit of cryoplasty over conventional angioplasty cannot be established as the number of randomised controlled trials is small and their quality is not sufficiently high. The technical success and primary patency rates seen in these trials are inconsistent and do not necessarily suggest a future role for cryoplasty in the treatment of PAD, but they cannot be reliably interpreted. Currently there are insufficient data to support the routine use of cryoplasty over conventional balloon angioplasty in the treatment of PAD.

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Background: 

Percutaneous balloon angioplasty is an endovascular technique for restoring blood flow through an artery that has become narrowed or blocked by atherosclerosis. Narrowing of the artery following angioplasty (restenosis) is the major cause of long-term failure. Cryoplasty offers a different approach to improving long-term angioplasty results. It combines the dilation force of balloon angioplasty with cooling of the vessel wall. This systematic review evaluated cryoplasty in peripheral arterial disease and provides focus for further research in the field. This is an update of a review first published in 2007.

Objectives: 

To assess the efficacy of, and complications associated with, cryoplasty for maintaining patency in the iliac, femoropopliteal and crural arteries in the short and medium term.

Search strategy: 

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched October 2012) and CENTRAL (2012, Issue 10). Trial databases were searched for ongoing or unpublished studies. We also searched the reference lists of relevant articles.

Selection criteria: 

All randomised controlled trials in which participants with peripheral arterial disease (PAD) of the lower limbs, or lower limb bypass graft stenoses, were randomised to cryoplasty with or without another procedure versus a procedure without cryoplasty were considered. This included trials where all participants received angioplasty and the randomisation was for cryoplasty versus no cryoplasty and trials where cryoplasty was used as an adjunct to conventional treatment (for example stenting) against a control.

Data collection and analysis: 

Two review authors independently reviewed, assessed and selected trials, extracted data and assessed risk of bias.

Main results: 

Seven trials (six primary cryoplasty and one adjunctive cryoplasty trial) with a combined total of 478 patients were included in this review. The trials reported patency and restenosis either by participant, lesion or vessel location. Follow-up ranged from 30 days to three years.

Target lesion patency measured at various time points in two primary cryoplasty trials showed no statistically significant difference between the treatment groups. The adjunctive cryoplasty study showed that cryoplasty was associated with improved patency only at six months (OR 5.37, 95% CI 1.09 to 26.49, n = 90).

Restenosis measured per patient (two primary cryoplasty trials) showed no statistically significant difference between the treatments. Restenosis measured by lesion (two primary cryoplasty trials) showed a statistically significant difference only within 24 hours of the procedure (OR 0.08, 95% CI 0.04 to 0.18, n = 192) favouring cryoplasty.

Need for re-intervention was not significantly different in primary cryoplasty trial participants (per participant: OR 0.27, 95% CI 0.05 to 1.52, n = 241, I2 = 89%; per lesion: OR 0.59, 95% CI 0.06 to 5.69, n = 307, I2 = 94%). The adjunctive cryoplasty trial did not report on need for intervention.

Immediate success of procedure (within 24 hours) was not significantly different in primary cryoplasty trial participants (per participant: OR 1.63, 95% CI 0.14 to 19.55, n = 340, I2 = 95%; per lesion: OR 1.81, 95% CI 0.19 to 17.36, n = 397, I2 = 90%). The adjunctive cryoplasty trial reported 100% success.

Limb loss, deaths from all causes and the risk of complications immediately after treatment showed no statistically significant differences between the treatments.

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