Plaque excision registry results spark controversy

According to the 2000 Transatlantic Inter-Society Consensus study (TASC), angioplasty and stenting has a one-year patency rate of 61-67%. In peer-reviewed, published literature, surgical bypass results at one year have demonstrated patency rates of 77-81%.

Plaque excision was performed in 505 patients, 617 limbs and 1,047 lesions. A total of 33.2% of presenting limbs had Rutherford Becker Score =5. Seventy-five percent of the lesions were located above the knee, of which 88.3% were de novo and 11.7% were restenotic. Moderate-severe calcification was present in 67.4% of lesions. Chronic total occlusions (CTO) accounted for 27.8% of lesions, whilst pre-dilation was required in 12% of all lesions. Stand-alone plaque excision was performed in 74.3% of patients, with an adjunctive stent placement rate of only 5.3%. Angiographic outcomes in stand-alone SilverHawk cases showed a greater than 75% reduction in the average diameter stenosis (pre-SH 85.7% vs. post-SH 10.1%). Acute post-procedure minor complications included grade C dissection (0.9%), perforation (0.6%), aneurysm (0.4%) and occlusion/thrombosis (0.2%).

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 10-30% rate of wound complications alone. Previously published peripheral stent studies have reported a complication rate of 7.3%.

The non-randomized TALON study involves investigators from 19 different hospitals in the US. It is designed to reflect "real world" practice by allowing treatment of blockages of any length and any diameter in the legs. All patients were eligible for the study, regardless of their clinical history and the severity of their disease. Over half have diabetes and/or coronary artery disease, and nearly one-third are smokers.

Ramaiah stated 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 peripheral arterial disease. In addition, 36% of the patients had multiple blockages treated during a single procedure. The average lesion length treated was 7.5cm 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. Before plaque excision, the arteries treated, on average, were 85.6% blocked with plaque. Treatment with SilverHawk reduced the blockage by over 85% to a residual 10.5%.

Follow-up data is available for 317 lesions that have reached the six-month time point. Revascularisation occurred in 35 of the 317 lesions for an overall TLR rate of 11.0%. The target lesion revascularisation rate (TLR) in patients with a single lesion treated was 4.6% (3/65). Of the 85 CTO lesions with follow-up data that have reached the six-month time point, the TLR rate was 8.2% (7/85).

"Peripheral artery disease has long been underdiagnosed and undertreated. 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. This data validates the encouraging results my colleagues around the country have experienced in their own hospitals with plaque excision," Ramaiah concluded.

However, following the presentation, Ramaiah was criticized by Dr Ken Ouriel for the inconclusive data on patency, although Ramaiah replied there was an 80% clinical patency rate at one year for all blockages treated with the SilverHawk System, which he said compares very favorably to other treatments used in the past for blockages in the leg arteries.

Dr Takao Ohki also criticized the data, claiming that non-protocol driven TLR is not a objective endpoint as it is affected by physician decision. Theoretically, one can have a 0% patency rate and 0% TLR. Therefore, Ohki said there was a need to clarify the financial incentives of the investigators as 11 of the original 12 investigators have stock options in FoxHollow Technologies.

In addition to the TALON data, the first one-year angiographic outcomes data on plaque excision were recently released by the Cardiovascular Institute of the South at the New Advances in Critical Limb Ischemia meeting. In that study, 89 patients were treated with SilverHawk and then followed for 12 months using CT angiography.

The results, presented by Dr David Allie, Director of Cardiothoracic and Endovascular Surgery at the Cardiovascular Institute of the South (CIS), showed that at one-year, 86.4% of the patients treated with SilverHawk were clinically patent (absence of TLR) and had not returned for a repeat procedure. The angiographic patency rate was reported at 80%. The study also reported that among patients who had threatened limb loss, treatment with SilverHawk prevented an amputation in 92%.

Allie noted 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 15.3cm, considerably longer than the mean lesion lengths of 3-12cm in most PTA and stent studies conducted in the legs. A total of 68% of the blockages treated were identified as C or D using the TASC classification system, the most difficult to treat.

"We are very encouraged by how well our patients have done long-term after plaque excision. Plaque excision appears to be a very 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 an amputation," Allie concluded.