News from ISET: International Symposium on Endovascular Therapy

Non-Surgical CryoPlasty Therapy May Save Legs, Early Research Suggests One hundred percent of people facing almost-certain amputation were successfully treated with a non-surgical therapy that gently cools and opens leg arteries clogged with plaque, according to preliminary data on 22 patients presented at the 17th Annual International Symposium on Endovascular Therapy (ISET). First available in August 2004 to treat patients with arteries that are blocked below the knee, CryoPlasty therapy is now offered at nearly 800 sites in the United States. CryoPlasty therapy fits into the treatment spectrum before the use of angioplasty and appears to avoid some of the complications seen in that procedure. It also can be used to treat other vessels affected by peripheral arterial disease (PAD), including arteries in the thighs and abdomen. Previously, amputation was the only option for some people with such advanced disease in arteries below the knee, many of whom are diabetic, said James D. Joye, DO, director of the Cardiac Catheterization Lab at El Camino Hospital, Mountain View, Calif., and co-inventor of the CryoPlasty technique. CryoPlasty is a ‘no-harm’ treatment that offers early, conservative management and can be used repeatedly not only avoiding or delaying amputation, but postponing the use of more invasive procedures. The data on 22 patients being presented at ISET by Dr. Joye are the first results from Below the Knee Chill, an ongoing multi-center study at 30 hospitals across the United States, which will enroll 100 patients who are likely facing amputation of a foot or leg within six months. All of the patients in the study have critical limb ischemia. Treatment in all 22 patients (100%) resulted in procedural success, meaning stenoses were 50% or less after CryoPlasty therapy. After treatment, the average blockage was 19%, compared to 87% before treatment. Immediately after the procedure, ankle or toe pulses improved in 17 of 20 patients (85%). Pulses were not measured in two patients. There were no procedural complications or adverse events. Follow-up is ongoing. Other data, on 102 patients who received CryoPlasty therapy to treat blocked upper leg or knee arteries, have shown: 83% of the arteries remained opened after nine months. Typically, 59% of blocked blood vessels treated with traditional angioplasty remain open after one year. 89% of people reported an improvement in leg pain while walking. CryoPlasty therapy involves the use of nitrous oxide, rather than saline, to inflate the balloon and cool it to -10 degrees. This in turn prompts several physical responses that open the artery and cause less scarring than occurs with traditional angioplasty. Repeat procedures for patients treated with standard balloon angioplasty and stent technology of the arteries below the knee are reported to be as high as 45%. The below-the-knee CryoPlasty procedure is performed using one of several new smaller-sized catheters, which received clearance from the Food and Drug Administration (FDA). Endologix Presents Clinical Data at International Symposium of Endovascular Therapy Three-Year Preliminary Data Analysis Following Powerlink® Procedure Suggests Decreases in Aneurysm Sac Diameter and Volume Endologix, Inc. announced that a clinical paper presented at the International Symposium for Endovascular Therapy (ISET) suggests that three years following treatment with the Company’s Powerlink® System, patients (from the pivotal PMA study) experienced decreases in aneurysm sac diameter and volume, and less angulation of the aorta. The clinical paper, Sac Remodeling with the Powerlink® Stent Graft for AAA, was presented by Dr. Rodney White, Professor of Vascular Surgery at Harbor-UCLA Medical Center. These results are based on our retrospective study that investigated changes in aneurysm sac anatomy, including maximum diameter of the aneurysm, volume of the aneurysm sac, length from the renal arteries to the aortic bifurcation and angulation of the abdominal aorta, during a three-year period in patients treated with a Powerlink System, said Dr. White. The design features of the Powerlink device, including its long main body, and single wire stent cage that provide for column strength, may positively influence the aortic sac remodeling that we found during this study. Paul McCormick, president and CEO of Endologix, commented, In spite of the success of minimally invasive treatment of AAA, there remain 50,000 to 60,000 patients who still undergo the traditional surgery, many due to concerns about the long-term results of the stent graft procedure itself. If the data demonstrates that the Powerlink design induces this favorable remodeling, it may provide greater long-term benefit for the therapy, permitting it to be applied to a larger patient population. Research Shows Minimally Invasive Repair of Ruptured Aortic Aneurysms Could Save More Lives Burst aortic aneurysms are so deadly that about 4 out of 5 victims die, either before reaching the hospital or during open surgery. The minimally invasive alternative is less risky and could save more lives, according to data presented at ISET. Frank J. Veith, MD, the William J. von Liebig Chair in vascular surgery at Montefiore Medical Center and professor and vice chairman for the Dept. of Surgery at Albert Einstein College of Medicine, Bronx, NY, presented data on 476 patients who received endovascular repair for burst aneurysms, of whom 91 (19%) died. On average, about 40 to 50% of people who have surgery for a ruptured aortic aneurysm die. Surgery is extremely risky for these patients, but until recently, it was their only hope, said Dr. Veith. Minimally invasive endovascular repair of the rupture avoids many of the dangers of surgery. As many as two-thirds of people who need treatment for a ruptured aortic aneurysm could be candidates for this technique. Every year, nearly 15000 Americans die from ruptured aortic aneurysms, making it the 17th leading cause of death in the U.S., according to the National Center for Health Statistics. If an abdominal aortic aneurysm (AAA) grows large enough, physicians often recommend that it be electively repaired with open or endovascular treatment before it ruptures. About 5% of people die during elective surgery and about 2% die during elective endovascular repair, according to results from the Dutch Randomized Endovascular Aneurysm Management Trial, recently published in The New England Journal of Medicine. First performed about 13 years ago, endovascular repair is increasingly common for elective repair of an aneurysm that is at risk for rupture. The technique involves an endograft placed in the aorta via percutaneous intervention. The flow of blood is redirected through the graft so the pressure on the aneurysm is relieved. Not every patient is a candidate because endografts are made in specific sizes and cannot accommodate all anatomical situations. Endografts typically are not used in emergency situations because the graft needs to be sized to fit the patient, which is done in advance of elective surgery. However, as the therapy has increased in popularity, more options and sizes are available, so obtaining the appropriate-sized endograft in an emergency is usually no longer a concern. Dr. Veith reported on 44 patients with ruptured aortic aneurysms treated at Montefiore Medical Center, as well as 476 patients treated worldwide. Seven of 44 patients (16%) required surgical repair because their anatomical features were not suitable for endovascular repair. Of 37 treated with endografts, 32 (85%) survived. Of the 476 patients treated at 38 centers worldwide, 385 (81%) survived. Dr. Veith emphasized that endograft repair avoids many of the risks of surgical repair, which involves making a large chest incision and replacing the weakened portion of the aorta with a graft. When an aneurysm bursts, blood pressure typically drops and bleeding slows; but when the abdomen is opened during surgery, the forces that limit bleeding are released, and the rupture bleeds more vigorously. The patient’s body temperature can drop dangerously once the abdomen is opened during surgery, and there is a risk of injuring other organs or structures in the area. Before and during endograft repair, we allow the patient’s blood pressure to fall to low levels by restricting fluid resuscitation. This limits the bleeding, and we have found this approach, which we call hypotensive hemostasis, to be very effective, said Dr. Veith. Women Should Receive Less-Aggressive Stroke Prevention Therapy Than Men Physicians have been criticized for not treating cardiovascular disease as proactively in women as in men. However, when it comes to stroke prevention, women may be treated too aggressively, suggests data presented at ISET. It’s of particular concern because, compared to men, the standard prevention treatment surgery is riskier for women and less beneficial, said Anthony Comerota, MD, director of Jobst Vascular Center in Toledo, Ohio, and principal investigator of a study that involved 569 patients tested and analyzed for risk of stroke. That’s not to say invasive stroke prevention isn’t beneficial for women, but physicians need to set the bar higher for women than men. The problem arises in interpretation of the standard test that is used to assess when the risk of a stroke occurring outweighs the risk of preventative treatment, which includes surgery and non-surgical placement of a stent. Typically, the test is interpreted in the same manner for both genders, leading to potential overestimation of a woman’s risk of stroke, said Dr. Comerota. When the carotid artery is 60 to 70% blocked, generally determined by duplex ultrasound, the benefit of treatment is thought to outweigh the risk of the procedure. However, women’s blood tends to flow faster than men’s in general, suggesting the results should be interpreted differently for the genders, said Dr. Comerota. In the study, duplex ultrasound was used to analyze the most-diseased carotid artery in 328 men and 241 women during a 10-year period at Jobst Vascular Center or The Toledo Hospital. Each patient also had an arteriogram. Researchers found that compared to men, blood flow in women was about 16% faster on average. When results are interpreted the same for the two genders, women potentially receive treatment when the blockage is less significant than it is in men, and therefore, when the risk of treatment outweighs the risk of stroke. Physicians prefer to use duplex ultrasound to determine the risk of stroke because it is non-invasive. We believe that is fine, as long as they interpret the results differently for the genders, said Dr. Comerota, who is also a clinical professor of surgery at the University of Michigan, Ann Arbor. At our clinic, we treat men when duplex ultrasound shows they have a blockage of 60 or 70%, whereas for women, we’re waiting until the duplex ultrasound suggests the blockage is about 80%. Studies have shown that carotid endartarectomy is riskier and less beneficial for women than for men. The recently reported Asymptomatic Carotid Surgery Trial (ACST) found that compared to men, women who had surgery had a 44% higher rate of stroke or death during the procedure, and half the long-term benefit. The risks of carotid artery stenting in men compared to women have not been studied. However, numerous studies show that using stents to open leg arteries is less successful in women than in men, said Dr. Comerota. The gender difference in treatment risks and results is likely due to several factors, he said. Women’s blood vessels are smaller and less compliant than men’s, making treatment riskier. Also, plaque is distributed differently in the carotid arteries between the genders. First Absorbable Metal Stent Successfully Treats Blocked Leg Arteries A new type of metal stent is absorbed within a few months of being placed, propping open blocked leg arteries until it is no longer needed, suggests preliminary research presented at ISET. A stent is really only needed for a couple of weeks, to allow the blood vessel to reshape and get strong, and after that time it is useless, said Marc Bosiers, MD, head of the Department of Vascular Surgery at A.Z. Sint-Blasius Hospital in Dendermonde, Belgium. We believe the absorbable metal stent could be a major breakthrough, because it provides a temporary solution to a temporary problem. This is the first bioabsorbable metal stent tested in humans, said Dr. Bosiers. An absorbable polymer stent has been tested in humans, but doesn’t appear to be as effective as the metal stent in propping open the artery. The absorbable metal stent is made of an alloy of 90% magnesium (occurring naturally in the body) and 10% rare earth elements. The absorption process begins within a week to 10 days, and tests have shown the stent is fully absorbed within 60 days, Dr. Bosiers said. The metal stent is completely absorbed into the vessel wall, without freeing particles into the blood streams. As soon as the stent is in place, the body begins to cover it with a layer of cells. Once that has occurred, the vessel wall begins absorbing the stent. The study included 20 patients who received absorbable metal stents to treat severely blocked arteries below the knee. One patient died of pneumonia unrelated to the procedure. Six months after treatment, 15 of 19 arteries (79%) remained open. Typically, only about 60% remain open after 6 months. When the stent is absorbed, it no longer inflames the blood vessel, theoretically reducing restenosis, said Dr. Bosiers. Researchers have begun testing the absorbable stents in the coronary arteries and expect to have results later this year.

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