Medical Device Daily Associate

One-year data from the multi-center TALON study on the SilverHawk plaque incision device, made byFoxHollow Technologies, (Redwood City, California) was presented last week at the annual meeting of theSociety for Vascular Surgery(SVS; Chicago) in Chicago by Venkatesh Ramaiah, MD, a vascular surgeon at theArizona Heart Hospital(Phoenix). Plaque excision is a minimally invasive procedure performed through a tiny puncture site in the leg or arm. The SilverHawk system uses a small rotating blade to shave away plaque from inside the artery. As it is excised, the plaque collects in the tip of the device and then is removed from the patient. The company currently offers five different SilverHawk models in the U.S., of various catheter diameters and tip lengths, to accommodate different artery sizes and amounts of plaque for use in the peripheral vasculature. Ramaiah reported an 80% rate of patency at one year for all blockages treated with plaque excision – meaning not requiring another procedure again. Peripheral artery disease (PAD) results from plaque in the arteries that blocks blood flow in the legs and the feet, producing leg pain and potentially leading to gangrene, tissue loss and amputation. The safety and efficacy data on plaque excision at one year compares “very favorably” to other treatments used in the past for blockages in the leg arteries, according to Ramaiah’s report. “PAD has long been underdiagnosed and undertreated,” said Ramaiah. “Part of the problem has been the lack of safe, effective and durable treatment alternatives. The data from the TALON study suggest we now have such an alternative.” He reported that of the 87 patients followed for one year after treatment with SilverHawk, nearly 30% of the procedures were for the most severe form of PAD, characterized by rest pain and/or tissue loss. Additionally, 36% of the patients had multiple blockages treated during a single procedure. The average lesion length treated was 7.5 cm in arteries above the knee. Despite the long length of the blockages treated, and the high percentage of multiple blockages treated, the average procedure time for plaque excision was 31 minutes. For the majority of the patients in TALON, these results were achieved with plaque excision as the only therapy used, with just 3.5% receiving a stent following SilverHawk. There were no serious complications reported, with 4.6% minor complications. Comparatively, bypass surgery is associated with a 10% to 30% rate of wound complications alone. Published peripheral stent studies have reported a complication rate of 7.3%,. The 12-month TALON results come on the heels of the first one-year angiographic outcomes data on plaque excision recently released by theCardiovascular Institute of the South(CIS; Houma, Louisiana) at the New Advances in Critical Limb Ischemia meeting. In that study, 89 patients were treated with the SilverHawk and then followed for 12 months using CT angiography, a non-invasive imaging modality, which provides physicians with 3-D images of the arteries to determine whether a blockage has reappeared following treatment. The results, presented by David Allie, MD, director of Cardiothoracic and Endovascular Surgery at CIS, showed that at one-year 86.4% of the patients treated with the SilverHawk were clinically patent and had not returned for a repeat procedure. The angiographic patency rate was reported at 80%. That study also reported that among patients who had threatened limb loss, treatment with the device prevented an amputation in 92%.“We are very encouraged by how well our patients have done long-term after plaque excision,” said Allie. “With over 150,000 amputations still performed in the U.S. each year, we are clearly in need of a better solution for PAD.” He noted that plaque excision appears to be a promising answer, both for patients suffering from mild to moderate leg pain and those with severe rest pain and tissue loss who are at high risk for amputation. Allie said that 86% of the patients who were treated had among the most serious forms of PAD marked by severe rest pain and tissue loss on the legs. The mean length of the blockages treated was 15.3 cm, considerably longer than the mean lesion lengths of 3-12 cm in most percutaneous transluminal angioplasty and stent studies conducted in the legs. Jason Mills, a medical technology analyst atFirst Albany Capital (San Francisco), wrote in a research report that while the data from the SVS meeting was positive, “in our view, there was (at this meeting), and probably will continue to be, skepticism from certain physicians about SilverHawk.” He said that some of the vascular surgeons he and his associates spoke to at the SVS meeting were skeptical concerning, for instance, the TALON endpoints (TLR/patency), suggesting that these endpoints are more subjective than an angiographic endpoint derived from, for example, ABI index and/or duplex ultrasound. While the data is positive, Mills pointed out that total lesion revascularization (TLR) rates are embraced by interventional cardiologists much more than by vascular surgeons, who do very few endovascular procedures at this point relative to the interventional cardiologists, who do more than 80% of the SilverHawk volume. However, he said that continued strong data may drive a “see-for-yourself” usage by “fence-sitters” in either or both of these specialties. “This is especially true,” he said, “given the superiority of the SilverHawk data in terms of TLR relative to stents, which at best in clinical studies has shown 31% TLR.” The company was founded in 1996 to commercialize the SilverHawk, but didn’t truly take off until June 2003, when the FDA approved the device to treat atherosclerosis in the peripheral arteries. The company, which eventually aims to seek FDA approval for cardiac uses, is now waiting for the FDA to approve a trial for bifurcation lesions in the heart and hopes to start the tests later this year. Such lesions, which occur in about 20% of patients with coronary artery problems, block the vessels of a main artery and its side branch. FoxHollow halted an earlier trial for coronary arteries after 28 out of 172 patients suffered adverse events, including 14 cases of heart attack, and eight patient deaths, according to financial filings. The company said the problems “resulted from a number of factors, including the patients’ overall poor health.” Another area the company is exploring is plaque analysis for large pharmaceutical and biotech firms, since plaque can be extracted from live patients. This could help companies perform early compound validation and new marker identification in the development of new drugs, it said.