CD&D

Drug eluting stents (DES) – wire mesh tubes that prop open a previously blocked artery to the heart –have gone a long way toward reducing restenosis in cardiac patients after percutaneous coronary intervention. But they've also created a host of potential complications from impairing imaging to hindering surgical revascularization or positive remodeling (an increase in arterial area).

A new bioabsorbable stent being tested by Abbott Laboratories (Abbott Park, Illinois) may solve some of those problems. One-year results from a study of 30 patients who have had bioabsorbable everolimus- eluting stents implanted demonstrated no stent thrombosis, no clinically driven target lesion revascularizations (retreatment of a diseased lesion), and a low (3.3%) rate of major adverse cardiac events (MACE).

"Doctor's tell me their patients often ask, 'How long do I have to have this stent inside me?'" Richard Rapoza, PhD, VP of R&D for the bioabsorbable stent program at Abbott told Medical Device Daily. "They don't understand or like the idea that they are permanent. For patients who have angioplasty, their vessels regrow in one to five years, but if you have a metallic stent, that's not a possibility. Now we are able to restore that possibility, we have a stent that degrades."

Abbott said this is the first degradable stent to ever be tested in humans.

The stent has a backbone of poly-L-lactic acid that provides the support and a coating of poly-D,L-lactic acid that contains and controls the release of the antiproliferative agent everolimus. Polylactic acid is a substance commonly used in medical implants such as dissolvable sutures. The substance reacts to water and is absorbed by the body over time.

Patients included in the trial had either stable, unstable, or silent ischemia and a single lesion that was suitable for treatment with a single 3.0 12 mm or 3.0 18 mm stent. Rapoza pointed out they were 60-70 years old and did not have complicated disease and no calcifications.

They were enrolled from four academic hospitals in Auckland, New Zealand, Rotterdam, The Netherlands, Krakow, Poland, and Skejby, Denmark. The composite endpoint was cardiac death, myocardial infarction and ischemia-driven target lesion revascularization. Researchers are checking patients at 30, 180 and 270 days, with an annual follow-up for up to five years, on blood clot formation rates.

No late stent thromboses were recorded. At 6-month follow-up, the angiographic in-stent late loss was 0.44 mm and was mainly due to a mild reduction of the stent area.

Abbott's stent loses mechanical structure in three to five months and the vessel can begin to move freely. "It holds an artery open long enough for healing to occur," Rapoza said. Remnants of the structure can remain up to two years after implantation. "We would expect an artery that is healed to function as it did before it became diseased."

Rapoza said one of the more interesting aspects of the study is to follow patients over the course of five years to see if their vessels can actually regrow. "We're looking to see if the theory that the vessel can re-grow post-one year is real," he said.

Another potential advantage of a stent that degrades is that patients can then discontinue antiplatelet therapy. Thienopyridines and aspirin, antiplatelet agents, are begun before stent insertion to reduce the chance of clotting within the stent, which may result in heart attack or death. But patients often prematurely stop taking the drugs.

"Complications related to DES are often related to patient compliance. If this stent is gone, patients won't need to continue antiplatelet therapy in the long term," Rapoza said. "The medications are expensive and older people have a problem complying with long term use of the drugs. Plus, when patients have other health problems, they have to stop the antiplatelet medications and then there are more problems."

The ABSORB trial is a prospective, non-randomized (open label) study designed to enroll up to 60 patients.

"We stopped enrolling at 30 patients because we wanted to see the results before adding the other 30 patients. We made some adjustments to the structure of the stent, changed the pattern to improve scaffolding and improved the degradation rate," Rapoza said.

"The positive results from this clinical trial form a strong basis for the development of additional bioabsorbable stent platforms with the potential to eliminate some of the restrictions posed by metallic stents in areas such as vessel imaging and vessel remodeling," said Patrick Serruys, MD, PhD, professor of interventional cardiology at the Thoraxcentre, Erasmus University Hospital (Rotterdam, the Netherlands) and co-principal investigator in the ABSORB study.

Rapoza said plans are in the works to launch a larger study in Europe, although Abbott has yet to release those details.

Elsewhere in the product pipeline:

• AtriCure (West Chester, Ohio) reported that the first patient was successfully treated in AtriCure's ABLATE clinical trial. The purpose of the ABLATE clinical trial is to evaluate the safety and effectiveness of AtriCure's Isolator Synergy bipolar ablation system for reestablishing normal heart rhythm in patients with permanent atrial fibrillation (AF), requiring concomitant open-heart surgery using the Cox Maze IV procedure. The Isolator Synergy bipolar ablation system is designed to create precise lesions, or scars, on heart muscle, which block irregular electrical signals and restore normal sinus rhythm. AtriCure specializes in cardiac surgical ablation products.

• ATS Medical (Minneapolis) reported initial clinical results of stand-alone ablation procedures and an overall expansion into the stand-alone market, using the ATS CryoMaze product line. This line of surgical products, indicated for the treatment of cardiac arrhythmias, is designed to replicate the original cut-and-sew Maze procedure (also known as Cox-Maze-III) by freezing lines in the heart to re-direct electrical impulses. The strengths of the stand-alone procedure using ATS CryoMaze are that it can be done through a small incision, which is appealing to the patient, and provides clinical results similar to the original cut-and-sew full Maze procedure – even in the patient populations that are historically the most difficult to ablate, especially for cardiologists. The robust clinical success of this procedure combined with the minimally invasive access site is leading to a rapid adoption of this procedure for surgical stand-alone procedures. ATS Medical makes cardiac surgery products.

• Boston Scientific (Natick, Massachusetts) reported FDA approval for three products in its cardiac rhythm management business. They include the Confident implantable cardioverter defibrillator (ICD), which helps protect patients at risk of sudden cardiac death; the Livian cardiac resynchronization therapy defibrillator (CRT-D), which provides cardiac resynchronization and defibrillation therapies in one device; and an upgraded Latitude patient management system, with enhanced remote monitoring capabilities. The Confident ICD features an enhanced AV search hysteresis feature designed to reduce unnecessary right ventricular pacing. The Livian CRT-D lets physicians provide patients with individualized therapy using the SmartDelay and Bi-V trigger features. The upgraded Latitude includes new patient alerts.

Additionally, the results of Boston Scientific's defibrillator lead study, titled REFLEx, were published in the January issue of the journal PACE. The study compared the company's Endotak Reliance G Gore-coated leads to non-coated leads. Reliance G leads have a Gore ePTFE coating designed to prevent tissue ingrowth. Tissue in-growth can make lead removal more difficult. Medical literature suggests up to 10 percent of leads may eventually need to be removed. A lead is an insulated wire that carries cardiac signals to the implanted device and also delivers energy from the device to the heart. In most cases, leads are passed into the heart through veins.

• Cambridge Heart (Bedford, Massachusetts) reported the publication of a proposed decision memorandum regarding Medicare coverage of Microvolt T-wave Alternans (MTWA) diagnostic testing. The Centers for Medicare & Medicaid Services maintained coverage of MTWA using the spectral analysis method and found insufficient evidence for coverage of MTWA using any other method. The proposed decision memorandum is the result of CMS' six-month evaluation of the relevant clinical evidence available to the agency and consideration of public comments submitted on the request to expand coverage to include the Modified Moving Average methodology. The memorandum proposes to continue the existing coverage of MTWA with spectral analysis.

• Concentric Medical (Mountain View, California) reported that results of the Multi MERCI trial will be published in the April edition of Stroke. The Multi MERCI trial was the second trial studying safety and efficacy of the Merci Retrieval System, a "corkscrew-type" device that is delivered into the brain to restore blood flow by engaging, capturing and removing blood clots that cause ischemic stroke. Patients treated with the newer Merci L5 Retriever had cerebral blood flow restored 57.3% of the time with the Merci Retrieval System alone. With the addition of adjunctive therapy, physicians successfully restored cerebral blood flow 69.5% of the time. For patients to be successfully revascularized, not only the target vessel, but all treatable downstream vessels needed to achieve TIMI 2 or 3 flow. In addition, a total of 36% of all patients treated achieved a "good" outcome at 90 days post procedure, a higher rate than reported in any other device trial in large vessel acute ischemic stroke patients. The company said these outcome data are superior to those reported in recent studies of other devices in which successful revascularization was not as stringently defined. Multi MERCI was a multi-center, prospective trial including 164 patients treated at 15 hospitals in the U.S. and Canada. All patients had moderate-to-severe, large vessel ischemic strokes. The trial included patients who were ineligible for or had failed treatment with t-PA. Patients had treatment initiated up to eight hours after stroke symptom onset, extending the three-hour treatment window for intravenous clot-dissolving drugs..

• Covidien (St. Louis) said the FDA has granted tentative approval for the company's abbreviated new drug application for its Kit for the Preparation of Technetium Tc 99m Sestamibi Injection. Covidien's tentatively approved product is a generic of Cardiolite, which is a myocardial perfusion imaging agent used for detecting coronary artery disease.

• ELA Medical (Denver), a Sorin Group company, reported the FDA's approval to market Isoline, its latest generation of defibrillation leads. Leads are insulated wires inserted through the vein as part of an implantable cardioverter defibrillator (ICD) or a pacemaker system. They are a key component of the implanted system. Connecting the device to the heart, the leads carry high voltage and electrical impulses from the implanted device to the heart when needed by the patient. The Isoline defibrillation leads have a multi-lumen structure with a silicone body and include an ETFE protective coating placed around the cables leading to the electrodes. The Sorin Group makes medical technologies for cardiac surgery.

• HemCon Medical Technologies (Portland, Oregon) reported the availability of its hemorrhage control dressing, ChitoFlex, to acute care professionals in two smaller sizes, 1"x 3" and 3"x 9" strips. HemCon said its decision to expand the ChitoFlex product line was the result of feedback asking for additional product flexibility for varying wound sizes. The original ChitoFlex dressing, which comes in a roll and measures 3" x 28", will remain available for purchase. A two-sided, "stuffable" wound dressing, the ChitoFlex family of products is made from chitosan, a substance found in shrimp shells. The shrimp shells are processed, chemically treated, made into bandage form and then sterilized. ChitoFlex dressings control severe bleeding within two to five minutes by becoming adherent when in contact with blood. The adhesive-like action seals the wound and attracts red blood cells to the dressing, forming a seal that stops hemorrhaging independent of the body's natural clotting. The dressings are antibacterial and effective on high-pressure, high-flow arterial bleeds.

• Medtronic (Minneapolis) reported the first human use of its investigational bifurcation stent. The new stent uses a Y-shaped design to match the anatomy of lesions that form at the junctions of coronary arteries. The BRANCH study is designed to assess the safety and deliverability of the Medtronic stent, which provides scaffolding to both branches of the bifurcation simultaneously without overlapping stents. Primary endpoints include cardiac death, myocardial infarction involving the target vessel, and clinically-driven target vessel revascularization 30 days post-implant. The bifurcation stent is intended to reduce the challenges associated with current two-stent bifurcation techniques, requiring two overlapping stents, one for the main branch. Delivered over a dual-wire delivery system through a single catheter, the new stent leverages Medtronic's balloon-tapering and -folding technology to minimize the delivery system's profile.

• Neoteric Technology (Vancouver, British Columbia) said that a new study released in this month's American Association of Blood Banks (AABB) Journal of Transfusion proves that dramatic time and cost savings can be achieved by hospitals that implement BloodTrack OnDemand. The study describes remote allocation, a new way of providing blood to patients. This process allows unallocated (non-crossmatched) blood to be stored in automated "smart" refrigerators in patient care areas such as the OR. When a blood unit is required, it can be electronically assigned by the refrigerator and labelled for a specific patient without involving the blood bank. Blood bank staff benefit from decreased workload through fewer blood requests, fewer returned units, increased inventory visibility, and increased job satisfaction by distributing the workload throughout the day. Clinical staff benefit from quicker access to blood at the point of care, reduced paperwork, increased confidence in giving the correct blood, and reduced time spent managing the overall blood delivery process.

• Omron Healthcare (Blannockburn, Illinois), a subsidiary of Omron Corporation and a manufacturer of medical, home healthcare and wellness products, reported development of the Hem-Solar Series, solar-powered digital blood pressure monitors. "Hen-Solar monitors will allow health practitioners and individuals to take blood pressure readings wherever sunlight is available," says Keiichiro Akahoshi, representative director and CEO of Omron Healthcare, saying the technology demonstrates the company's focus on "environmental stewardship." Omron Healthcare has developed two blood pressure monitors for the series, a manual upper-arm and automatic upper-arm model. Both are charged by exposure to sunlight through the solar panel at the back of the product. After just four hours of direct exposure to sunlight, the manual model can take more than 100 readings while the automatic model can take 28 readings. When fully charged (about 15 hours with the manual model and 24 hours with the automatic model), the manual model can take measurements more than 280 times and the automatic model more than 100 times. Wherever sunlight is available, the monitors facilitate easy readings, regardless of proximity to an electrical supply source. The products feature AES plastic material, durable against UV light; and embossed buttons on the front panel to protect against exposure to precipitation. Omron said it plans to release the products in spring 2009. It said it will continue efforts to improve device quality with respect to temperature and humidity, and will make the devices more airtight so that they are rechargable under a wider variety of conditions.

• OrbusNeich's (Hong Kong) Genous bio-engineered R stent is feasible and safe for use in acute myocardial infarction patients, according to a paper published in the American Heart Journal. Unlike drug-eluting stents, Genous, which is coated with an antibody, captures a patient's endothelial progenitor cells (EPCs) to accelerate the natural healing process. EPCs circulate in the bloodstream and are involved in the repair of blood vessels. When attracted to the surface of Genous, EPCs rapidly form an endothelial layer over the stent that provides protection against thrombus and minimizes restenosis. OrbusNeich makes devices for the treatment of vascular diseases.

• Orqis Medical (Lake Forest, California) said that the company's MOMENTUM Trial Abstract was accepted for Late Breaking Clinical Trial presentation at the upcoming annual meeting of the American College of Cardiology (Washington) in Chicago. MOMENTUM evaluated the percutaneous Cancion System in patients with acute decompensated heart failure. "MOMENTUM is a landmark study examining the hemodynamic and clinical effects of the Cancion System in managing patients hospitalized with heart failure inadequately responsive to medical therapy," said Barry Greenberg, MD, who will present the abstract. Orgis makes products for treatment of heart failure.

• St. Jude Medical (St. Paul, Minnesota) said that it has distributed a programmer software upgrade to eliminate a random, low-frequency anomaly that could affect ventricular sensing in the Epic and Atlas families of implantable cardiac defibrillators. Specifically, a potential loss of ventricular sensing has been attributed to an extremely rare timing sequence that occurs in a very small (61 microsecond) timing window. To date, an incidence of 0.00006 of the subject device population (eight out of about 143,000 implanted since July 2002) has been found to exhibit a loss of ventricular sensing. The new software will be downloaded into the device during a patient's next routine check up and will fully prevent the anomaly from occurring in the future. The non-invasive software upgrade can be completed in approximately 10-20 seconds, during which time the device will maintain full functionality. St. Jude makes products for cardiac, neurological and chronic pain patients.

• Terumo Heart (Ann Arbor, Michigan) reported receiving conditional FDA approval to begin enrollment in the U.S. pivotal trial of the DuraHeart LVAS for bridge-to-transplant. David Munjal, MD, VP of studies of regulatory affairs and quality systems at Terumo Heart, said: "The conditional approval was granted pending answers to some additional questions. Terumo Heart has already responded to the FDA concerning these questions and final approval is anticipated in the near future." The DuraHeart LVAS is a third generation circulatory support device intended to provide cardiac support for patients who are at risk of death due to end-stage left ventricular failure. Terumo Heart is a division of Terumo (Tokyo).

• Volcano (San Diego) reported FDA clearance of the s5-Revo and s5-FFR (fractional flow reserve) options. These two new product offerings now enable rotational IVUS and FFR to operate on the same integrated Volcano s5 imaging system as Volcano's previous line of phased array IVUS catheters and functionality. For the first time, physicians can choose among three powerful diagnostic tools – all on the same integrated IVUS platform. Earlier generation consoles included only one of the three technologies now available on the s5. If a hospital wanted to equip a new lab with all three technologies, they would have to acquire three separate consoles, each with a different measurement modality, training requirements and data storage protocols. The Volcano s5 can now accommodate the three primary intravascular diagnostic tools in regular use by cardiologists (high frequency rotational IVUS, fast and simple digital IVUS, and pressure-based FFR guidewires) on a single platform. Volcano specializes in intravascular ultrasound and functional measurement technology.