Information publicised at the ISET meeting in Miami suggests that cutting balloons may be coming of age for use in peripheral areas. The large-scale Cutting Edge trial, which is now moving forward, aims to demonstrate the safety and effectiveness of large cutting balloons for use in the periphery for FDA approval in the US.
Until recently, experience in peripheral applications has been limited to smaller cutting balloons designed for use in the coronary arteries. These devices range from 2.0mm to 4.0mm in diameter and are therefore too small for most lesions in peripheral vessels. Devices sized from 4.5mm to 8.0mm are now available outside of the US and are currently undergoing clinical trials in the US.
At ISET 2003 Dr Jeffery Siegel, Director of Radiology, Dallas Nephrology Associates explained that in an effort to demonstrate the utility of peripheral cutting balloons the Cutting Edge trial, a US prospective randomised clinical trial of the device for use in haemodialysis access grafts, was started in 2002. This study aims to recruit 340 patients from 20-30 participating centres with the primary objective of demonstrating superior target lesion primary patency compared to the angioplasty control up to six months post procedure. According to Siegel, “This trial is already over 60% enrolled. It is a very well controlled study involving outflow vein stenoses in dialysis access. Interim data has not been released on this study, due to FDA guidelines, but our own data shows a significant decrease in the number of patients returning for repeat intervention in the cutting balloon subgroup. This will need to be further validated as the study is completed and the appropriate statistical tests applied.
The Cutting Edge trial is large enough to evaluate differences in restenosis when comparing cutting balloons to PTA. Study entry criteria are limited to ensure that only a subgroup of lesions found in dialysis access patients will be entered into the study. The final results of this study are expected to be available later this year. The Cutting Edge trial will provide data comparing this cutting balloon technology to standard angioplasty in one peripheral application, but additional clinical studies will be needed with long-term follow up to establish whether it produces significant added benefits over conventional therapy.
Commenting on the advantages offered by cutting balloons, Siegel said, “Cutting balloons, particularly in venous strictures where we are currently studying them, appear to be more effective in releasing the circumferential strictures than conventional PTA while producing less vessel trauma.
However, there is a warning on the effectiveness of this technology from experience in coronary surgery. Coronary cutting balloons have been widely accepted worldwide and are used especially in complex coronary lesions and in-stent restenosis. Initial hopes that the devices would significantly decrease restenosis rates by reducing vessel wall trauma associated with PTA have not been realised according to some commentators. “I agree that the longer term coronary data is less than stellar,”said Siegel. “However, the pathophysiology which we are treating, particularly in vein stenoses, is rather different to what is found in coronary arteries.”He believes that the “length and one-to-one comparison with balloon angioplasty in the Cutting Edge trial should help to confirm or refute this theory.
Another possible concern is difficulty of negotiating tortuous vessels because of the stiffness of the device. In such cases, traditional balloons are the main alternative. Dr Siegel, however, dismissed this problem stating, “I have no issues with negotiating anatomy with the cutting balloons that we have been supplied for the study [Cutting Edge]”He added: “No failures to cross the target lesions have been reported to my knowledge.
Some clinics are also concerned about the cost of the technology. This could be a barrier against widespread adoption, especially in the current economic climate. Until cutting balloons in the periphery have definitely proved their worth in it is unlikely that they will be accepted for widespread use in hospitals. If clinical trials are successful, Siegel says that “In certain lesions, no matter what the cost, this device will be desired and used.
Cutting balloons are devices used in percutaneous coronary interventions. In contrast to a typical balloon they have three or four fixed blades called artherotomes embedded longitudinally along the length of a balloon. As the balloon is inflated the balloon material uncovers these and the atherotomes are embedded into the area of the plaque that the balloon is inflated within. This scores the plaque and creates a controlled cut within the plaque. This has been found to be quite useful in lesions that are resistant to high pressure balloon inflation and with lesions with some mild calcification that are not severe enough to require rotational atherectomy with a rotablator. It has also proved useful in some ostial lesions that have a traditionally high amount of elastic recoil. Evidence to date, however, suggests that the most frequent application of the cutting balloon is for patients that have developed stent restenosis.