Medical Device Daily Contributing Writer

BELLEVUE, Washington – The 6th annual SIS conference, formerly known as “Summer in Seattle” but now called “Science Innovation Synergy,” was held here last week at the well-appointed Meydenbauer Conference Center. As in previous years, the meeting was well-attended, and it featured some of the interventional community's best-known physicians addressing a wide range of topics of current interest.

This year, for the first time, a full two days was devoted to an “Emerging Technologies Symposium,” with a plethora of interesting topics such as cardiovascular imaging, structural heart disease and repair, electrophysiology and catheter-based ablation, and a full day on vascular therapies.

The field of peripheral vascular intervention has emerged in dramatic fashion in the last few years, as clinicians realize that peripheral artery disease (PAD) is an enormous problem.

Also called peripheral vascular disease (PVD), PAD is characterized by the accumulation of plaque in the arteries (primarily in the legs) and leading to a myriad of serious problems: stroke, heart attack, amputation, or – if untreated – death.

According to the Sage Group (Atlanta), a medical device market research consulting firm, an estimated 12 million Americans currently suffer from PAD. It is further estimated that only 14% of these patients are currently receiving intervention.

The Sage Group has noted that several powerful market drivers are expected to approximately triple the PAD space in the next few years – aging of the population, increasing PAD awareness, better diagnostics, improved therapeutics and earlier intervention, hopefully reducing the number of amputations.

With regard to leg amputations, viewed as a last resort for the most severe cases of PAD, it is believed that more than 150,000 leg amputations performed annually in the U.S. Not only is the number of procedures shockingly high, the prognosis for these amputees is horrible, only one-third achieving full mobility and, worse, up to 40% dying within two years of the initial amputation.

But awareness of the problems brought on by PAD has increased significantly. For example, the Society of Interventional Radiology (Fairfax, Virginia) and several other key organizations are sponsoring Legs For Life, a community public information program.

Additionally, the tremendous success enjoyed In the past few years by two publicly companies, Fox Hollow Technologies (Redwood City, California) and Spectranetics (Colorado Springs, Colorado), has spurred interest by public and private investors in this market. Fox Hollow has aggressively marketed the SilverHawk atherectomy device, a product that removes plaque mainly from the upper leg peripheral arteries, and Spectranetics has enjoyed strong momentum with its excimer laser for plaque removal mostly in the lower legs.

Pathway Medical Technologies (Redmond, Washington), an interesting, privately-financed company addressing this market, was presented by SIS co-director, William Gray, MD, director of endovascular services and associate professor of clinical medicine at Columbia University Medical Center (New York).

According to Gray, one of the physicians on the company's Scientific Advisory Board, the Pathway PV System is a rotating, aspirating, expandable catheter used in the removal of atherosclerotic debris and thrombus from the peripheral vasculature. By combining the two actions of aspiration with differential plaque removal, the system is designed for the preemptive removal of both hard and soft diseased tissue with minimal damage to the wall.

Pathway PV consists of a console, flexible disposable catheter and control pod. Since the company's founding in 1998, improvements have been implemented in the product, now undergoing clinical trials in Europe. The company is now half-way completed on a 150-patient registry to assess acute procedural results, plus safety, at six months.

Following completion of its European trial, Pathway intends to file for 510(k) FDA approval, eyeing hoped-for 2008 U.S. launch.

According to Gray, this aspirating rotational atherectomy “is a viable therapy and unique in several aspects, including calcium management, stand-alone results and a reduced rates of restenosis.”

Another interesting talk in the peripheral vessel management space – “Endovascular Aneurysm Repair” – was delivered by Lance Diehl, MD, a vascular surgeon at Presbyterian Hospital (Charlotte North Carolina), providing an overview of abdominal aortic aneurysm (AAA) surgical and endovascular repair.

According to Diehl, AAA “is a vastly undiagnosed and under treated disease.”

While the prevalence of AAA may be about 1.2 million Americans, only 15% of these are diagnosed and less than 70,000 treated annually. According to Diehl, roughly 22,000 of these 70,000 patients are treated via endovascular aneurysm repair (EVAR). AAA increases significantly as the population ages and therefore presents an important market opportunity.

The two major interventional options for AAA repair are open surgery and EVAR. The former is highly invasive, with a mortality rate of 2% to 5%, a lengthy hospital stay of about 10 days and a convalescence period that can be as long as four months. According to a 2001 article in the Journal of Vascular Surgery, 18% of AAA open surgery patients said they would not undergo AAA repair again, knowing how traumatic the recovery process would be.

EVAR, in contrast, is minimally invasive, with far less morbidity, mortality risk and a faster return to full activities, which Diehl put at two to four weeks.

Two well-regarded European clinical trials, the UK-based EVAR 1 and the Dutch-based DREAM trial, have shown EVAR to have a far lower rate of short-term mortality and secondary interventions.

Diehl cited the recently-enacted AAA Medicare screening program called Screening Abdominal Aortic Aneurysm Very Efficiently (SAAAVE) as a key driver in the EVAR market. The program allows ultrasound AAA screening for patients when they initially join the Medicare system, although it is restricted to males over 65 with a history of smoking, and men and women with a family history of AAA disease.

“I believe that over time, SAAAVE will reduce the risk of AAA disease,” Diehl said. Diehl noted that a significant trial, called Positive Impact of EndoVascular Options for Treating Aneurysms Early (PIVOTAL), was begun about one year ago.

PIVOTAL is a randomized trial comparing early AAA stent graft intervention to medical surveillance, enrolling nearly 1,700 patients at more than 50 centers. Primary endpoint is the cumulative occurrence of the composite of rupture or aneurysm-related death within three years. Among secondary objectives are all-cause mortality and aneurysm-related mortality in smokers vs. non-smokers, aneurysm rupture, duration of hospital stay, procedure duration, and other endpoints related to the use of the stent graft.

The Cleveland Clinic (Cleveland) is the coordinating center for the trial, which is using the Medtronic (Minneapolis) AneuRx abdominal aortic stent graft system in patients from the treatment group. Medtronic's device has the lion's share of the domestic EVAR market today.

An interesting aspect of PIVOTAL is that it will treat small abdominal aortic aneurysms, those smaller than 5 cm in diameter that meet certain conditions and compare that approach to periodic surveillance (“watchful waiting”). Typically, most physicians do not recommend an intervention until an AAA reaches at least 5.5 cm or are growing rapidly. The risks of a rupture increases dramatically once an AAA exceeds 6 cm.

Diehl said that while it will be several years before these results are available, it is an important trial to further establish EVAR's legitimacy and benefits.