Whether you’re learning about or evaluating any of the high-cost, high-tech products used in cardiovascular specialties, such as stents, it’s easy to be swept up by all the clinical study hues and cries and hype – whether positive or negative – and allow it to influence your opinions and decisions.

Several experts have one word of advice for you.

Don’t.

Even though you can trace the term stent to an English dentist from the mid- to late 1800s named, coincidentally, Charles Stent, clinicians originally embraced the device for cardiovascular, peripheral and urological applications in the mid-1990s. Back then, these tiny mesh tubes were composed of stainless steel. Called bare metal stents, these devices used to prop open clogged arteries eventually developed a weakness. Over time, muscle tissue formed around the stent, effectively reclogging the vessel in what is known as restenosis.

Manufacturers quickly exhausted research and development efforts, rolling out new – and more costly – models made with more biocompatible materials, such as cobalt-chromium, and then by decade’s end drug-eluting stents, which were coated with a polymer designed to release anti-inflammatory agents to prevent restenosis.

"It’s hard to point to an industry that innovates more than the medical industry," said Michael Carpenter, vice president, spaceTRAX, InnerSpace Corp. "We see all these devices in our global product databases. While our customers are able to reduce the amount of inventory they stock because of PAR level management and visibility, their overall costs are increasing, due to the introduction of new technology, which tends to be more expensive. In fact, products vastly more expensive are being stocked today than 12 months ago."

Recent studies have shown, however, that even the drug-eluting stents may be failing in their mission. But you should read those studies carefully.

"With regard to recent studies that show complications with drug-eluting stents (DES), the jury is still out," said Amy Kottler, R.N., director, horizon scanning services at market research firm Hayes Inc., Buffalo, NY. "There is still not enough high-quality clinical trial evidence available in the peer-reviewed published literature to definitively determine if complications associated with DES are significantly greater than those associated with bare-metal stents."

Consequently, both Kottler and colleague Tira Pandolf, Ph.D., managing editor of "Hayes onHealth" newsletter, encourage the consideration of the following three factors when reviewing news stories about DES complications:

1. Length of patient follow-up is not all that long.

2. Operator skill can influence adverse outcomes independent of the technology (device). "We use the example of proper anticoagulation prior to implantation, but there are other variables such as physician training, number of cases performed, etc."

3. Patient selection criteria for DES.

"There has been a ton of research done on drug-eluting stents," Pandolf said. "The biggest controversy we’ve found is in patient selection. Some studies may report findings based on patients with different levels of risk. A patient who experienced a severe cardiac event may experience blood clotting and the need for revascularization. Other studies may target different areas, such as vessel failure versus restenosis but still reach similar conclusions."

Important considerations for the cath lab include how many repeat procedures a patient will have to undergo, as well as how well anticoagulation protocols after stent implantation were followed, according to Kottler and Pandolf.

"Because of all these questions it’s very difficult to use the studies that have been published to come to a definitive conclusion that a drug-eluting stent is better or equivocal to a bare metal stent," Kottler said. "The jury’s still out on that. It’s really not clear whether there are true increases in risk with respect to late thrombotic events.

"We separate the science from the hype but certainly everyone’s attention has been raised," she continued. "From a global perspective, however, the cath lab is here to stay. We’ve seen the shift from open heart to angioplasty to stenting. But, angioplasty is not going away."

Pandolf concurred that discretion is necessary. "You can’t go by one study alone," she said. "You need to see more information from hospital and patient registries but there are HIPAA implications."

Second-generation drug-eluting stents with nanocoatings, as well as semi and fully absorbable models, promise to eliminate the restenosis problem. But they’re being tested in a variety of anatomical areas and due to be released within 24 months.

One is currently available in Europe, according to Jennifer Sisk, managing editor and senior research analyst for "Hayes Medical Technology outlook," Hayes Inc., Lansdale, PA. "It offers continuous drug delivery over 30 days," Sisk said. "But the stent isn’t fully absorbed. Just the polymer coating and the drug. We know that there are absorbable metal stents in clinical trials right now, but they are further along in development for the peripheral arteries and not coronary applications." For example, BioTronik makes one with a metal-magnesium alloy that is absorbed over time, she added. And Abbott is developing a fully absorbable stent for coronary applications.

"The initial idea was to create a fully absorbable mesh stent," Kottler noted.

Another pricey, but clinically effective product is the SilverHawk plaque excision system by FoxHollow Technologies Inc. The Food and Drug Administration cleared it for use in peripheral vascular procedures but not for coronary or carotid arteries. However, Sisk suspects off-label use for coronary arteries happens anyway because the product’s already being used in Europe for those applications.

Basically, SilverHawk is used to treat certain patients with peripheral artery disease who are facing limb amputation. "Although open surgical bypass, angioplasty, and stenting are used to treat blocked peripheral arteries, no endovascular intervention has yet been proven to effectively prevent lower limb amputation," Sisk said. "Up to 35 percent of patients with critical limb ischemia (CLI) require limb amputation. Although angioplasty and stenting are used to treat peripheral artery blockages, restenosis rates are really high, and stents in the lower leg are prone to fracture.

"SilverHawk is attracting attention because some studies have found that it can prevent or lead to less extensive amputation, or delay amputation in some patients with severe CLI," Sisk continued. "And it is a short minimally invasive procedure that is performed in an interventional radiology suite or cath lab."

While SilverHawk may have limited patient applications it generates a secondary benefit that has strong R&D applications, according to Kottler. "The SilverHawk is capturing plaque for further study and for use in researching biomarkers for atherosclerosis," she said.

"They’re extracting plaque for research purposes to determine what causes clotting and how to diagnose it earlier with blood tests or treat it earlier with medication," Sisk added.

Sisk said she anticipates a bioabsorbable stent will reach the U.S. in late 2007 or early 2008. Meanwhile, the SilverHawk is in clinical trials right now for coronary applications so she expected a regulatory decision for coronary procedures by 2008.

"In the future it appears that more and more products will be coated with anti-rejection pharmaceuticals and similar agents, tracking chips, etc.," said Thad Mac Krell, director of business development, Owens & Minor Inc. "This will take place in cardiology as well as radiology, orthopedics, spine, heart, vascular, etc., products. Combining hardware and drugs will create unique delivery, handling, storage, tracking and reporting requirements, many of which will fall to the materials management department to address for the hospital."