Dr Gunnar Tepe, an assistant professor of radiology at the University of Tuebingen, Germany, presented early multi-center data on the use of paclitaxel-coated angioplasty balloons that avoids the need for stents in the lower limb arteries. The drug-coated balloon concept (developed by Bavarian Medical Therapies) has proven effective in opening previously stented coronary arteries. The balloon is coated with paclitaxel, which is used in the treatment of breast and other cancers. When the balloon is inflated, the drug is transferred from the balloon to the plaque.
Studies have shown that, within a year, about four in ten conventional lower limb angioplasty procedures need to be repeated because of restenosis.
“The drug prevents the growth of scar tissue that can cause restenosis,” said Tepe. “We’re employing the same drug used in drug-eluting stents, except the drug is delivered in a much shorter period of time and we don’t leave behind a foreign object – a coated stent, which itself can cause problems down the road. Also, because the coating on the stent remains after the drug has been completely delivered to the vessel wall, it may cause undesired effects later.”
In coronary arteries, drug-eluting stents have been very successful, but limited early research suggests they have not worked well in leg arteries because they are larger than coronary arteries and the clots are longer, requiring excessive amounts of the drug. Also, depending on the location of the lesion, stents can become twisted and bent due to leg movement, leading to breakage and clotting. However, non-drug-coated stents have been shown to be useful in certain cases in the treatment of peripheral arterial disease, including: repairing arteries that are dissected during treatment; opening completely occluded vessels; managing heavily calcified lesions and treating vessels for prevention of early restenosis.
The drug-coated balloon study includes 150 patients treated at three centers in Germany. The patients were evenly divided among three groups: those who received treatment with drug-coated balloon angioplasty, those who had conventional angioplasty with a non-coated balloon, and those who had conventional angioplasty with the drug in the contrast media.
Tepe presented early results on a portion of the patients in the first two groups: 20 who received angioplasty with the drug-coated balloon and 25 who received conventional angioplasty. Preliminary research shows that after six months the drug-coated balloons were significantly more effective than the non-coated balloons at preventing restenosis. He showed that the 20 evaluable patients in the test arm had a greater mean lumen diameter than those who were treated with uncoated balloons. The difference between the diameters was statistically significant (p=0.029). Analysis of the differences is continuing, he said. Researchers will continue to follow the patients for two years to determine if the incidence of restenosis remains reduced.
“Our early results suggest the effects of drug-coated balloons are by far superior to uncoated balloons. Careful analysis of data and more research are required to confirm the findings and explore additional applications,” Tepe commented. “If research bears out, drug-coated balloons could be a very useful option for treating occluded arteries. In particular, they could play a major role in the peripheral arteries, because the incidence of restenosis is higher than in all other parts of the body. In addition, all other successful methods used to gain a better long-term benefit in the coronary arteries have failed in the peripheral arteries.”
Coating the balloon with the drug allows more of the drug to come into contact with the plaque than is the case with stents. This is because the drug covers the entire balloon and is wholly transferred to the artery surface. Because stents are mesh, not solid, the drug coating is concentrated on their struts. Tissue that comes in contact with the struts receives more of the drug than the surrounding tissue. Furthermore, the drug-coated balloons deliver to the vessel wall immediately, and in one dose. Early research on animals suggests that the effect persists in spite of rapidly decreasing drug concentration.
Dr Barry Katzen, medical director of the Baptist Cardiac & Vascular Institute, Miami, FL, said: “We really have nothing much to offer patients to prevent restenosis in the leg arteries. Even drug-eluting stents have not proven successful in peripheral arteries, and that is why this concept of drug-coated balloon catheters is so exciting, particularly if the early success seen in these studies can be extended to the long-term.”
He also added that if the drug-coated balloons did prove successful they could eliminate the enormous expense of the use of stents in the peripheral arteries. However, Katzen warned that the devices would not prevent some of the other problems of angioplasty, namely occasional acute recoil.