Innovations in EP technology set the pace at HRS meeting

By Larry Haimovitch

Medical Device Daily Contributing Writer

May 18, 2010

DENVER — The 31st annual scientific sessions of the Heart Rhythm Society (HRS; Washington) took place here last week. Once again, attendance was at record levels, with strong interest from outside the U.S. as the rapidly emerging field of electrophysiology (EP) continues to ascend in importance in the healthcare world.

In past years, HRS has sponsored an "AF Summit," focusing attention on this very important arrhythmia with a one or two day symposia. While this event was not planned this year, atrial fibrillation (AF) was still a very prominent feature of this year's HRS.

Two new studies strongly supported the use of catheter ablation (CA) to treat AF. more than 37,000 patients were enrolled over a three-year period and were split into three groups: treated with AF ablation, treated with traditional AF medications and patients without AF.

The study found that patients treated with CA are much less likely to develop Alzheimer's disease or other forms of dementia and also have a significantly reduced risk of stroke and death compared to patients with AF who are not treated.

For example, 2.2% of AF ablation patients suffered a stroke with a 6% mortality rate. Patients who were treated with medications suffered a 4.7% stroke rate and a mortality rate of 23.5%. A similar large benefit was demonstrated for Alzheimer's and other types of dementia.

According to the co-principal investigator John Day, MD, of the Heart Institute at Intermountain Medical Center (Salt lake City), "our studies shed light on the positive outcomes of catheter ablation treatment not only to reduce AF but also to help patients lower their risk of developing Alzheimer's disease, suffering from a stroke or worse, loss of life."

At a Late Breaking Clinical Trial session, Medtronic (Minneapolis) released new data from its pivotal AF clinical trial Sustained Treatment of Paroxysmal Atrial Fibrillation (STOP AF), which treated patients with paroxysmal atrial fibrillation (PAF). This form of AF, which accounts for about one-third of all AF, is characterized by intermittent and self-terminating bouts of AF that typically last a week or less.

STOP AF showed that 80% of patients experienced a reduction in their AF symptoms after treatment with the Arctic Front cryoablation balloon system. Perhaps more importantly, measures of the physical and mental quality-of-life showed significant improvements when compared to baseline measurements.

"The significant reduction in AF-related symptoms observed in this trial demonstrates the potential relief that cryoablation therapy can provide to patients suffering from symptomatic paroxysmal AF," said Jeremy Ruskin, MD, chair of the STOP AF trial steering committee and director of Cardiac Arrhythmia Service at Massachusetts General Hospital (Boston).

The STOP-AF procedure, which were initially reported at this year's American College of Cardiology (ACC; Bethesda, Maryland) is by no means flawless. For example, the mean procedure time averaged over six hours (with the longest being nearly 11 hours) with average fluoroscopy time of slightly over one hour, with the longest of nearly four hours.

In addition, the overall stroke and transient ischemic stroke rate was a high 3.1% and phrenic nerve palsy, which causes difficult and labored breathing, occurred in 11.2% of patients immediately post-procedure and persisted for one year in 2.5% of the patients.

In addition, the reported 70% success rate was substantially buoyed by the fact that 31 patients needed a second procedure, leaving 83 patients with first time success. That translates into a 51% success rate from a one-time cryoablation treatment, which is not overly impressive. For comparison, the success rate of radio frequency ablation is generally believed to be about 50%-60% for a primary procedure and 70%-80% with a second procedure although there is very little hard data on this matter.

The consensus of industry experts and EPs that Medical Device Daily interviewed during HRS is that Medtronic will attain an FDA approval, premised upon the trial meeting its primary safety and efficacy endpoints. However, most industry observers believe that the lengthy procedure and fluoroscopy times and its underwhelming efficacy will limit its market adoption.

The Arctic Front is CE mark-approved and is commercially available in Europe. In mid-March, Medtronic reported that it had submitted its PMA to the FDA. If approved, this device will become the second AF catheter system to reach the U.S. market. In February 2009, Biosense Webster (Diamond Bar, California), a Johnson & Johnson (New Brunswick, New Jersey) company, attained clearance for its Navistar Thermocool catheter.

One of the participants in the AF ablation market, Stereotaxis (St. Louis) held an analyst's briefing during HRS. One of the main messages conveyed by its CEO Mike Kaminski was that the company is working diligently to drive adoption of its installed base of more than 140 systems worldwide.

Clinically, the company has an impressive story to tell. To wit, its success in ventricular tachycardia (VT) ablation is considerably better than manual VT ablation, its safety profile is outstanding, with a vastly lower rate of major adverse events. Importantly, its procedure times are less than the conventional approach and this results in a 50% reduction in fluoroscopy time.

Its magnetic-assisted intervention system has been described as "disruptive" because it can precisely and remotely guide the devices used in EP procedures. However, because there is a steep learning curve, which the company pegs at 50 to 75 cases, usage of its system and consumption of disposables has lagged.

A concerted effort to boost usage appears to be bearing fruit, as there has been a 40% increase in its weekly North American procedures since September 2009. This has translated into several favorable metrics, including a 26% year-over-year recurring revenue growth with 50% of recurring revenue now procedure-related and 17 U.S. reference sites, up from nine in January.

There was considerable discussion of new technology that Stereotaxis has recently introduced. This includes its innovative Odyssey network, which during HRS was featured and demonstrated in the Siemens Medical Solutions (Malvern, Pennsylvania), Philips Medical Systems (Andover, Massachusetts), and Biosense Webster booths. The comprehensive Odyssey Enterprise Solution is a fully integrated, real-time information management platform to integrate, record, and network interventional lab data throughout hospitals and around the world.

Its next generation 3-D mapping system developed by Biosense Webster offers three significant benefits, including advanced catheter location technology, faster anatomical mapping and a new patient interface provides a central point for catheters and equipment.

CEO Kaminski concluded the meeting, pointing to the recent strong trend in procedure growth and said that "I am pretty bullish that we are now doing the right things to grow this company."

Another company that has been showing considerable progress, albeit in a clinical phase, is Endosense (Geneva, Switzerland). During HRS, the company released the 12-month data from the Touch for Catheter Ablation (TOCCATA) study that again showed that its TactiCath force-sensing ablation catheter can improve catheter ablation clinical outcomes.

TOCCATA was an eight-center, prospective study designed to evaluate the safety and effective performance of the TactiCath. Investigators used the TactiCath to perform catheter ablations on 76 patients, including 34 with paroxysmal AF. Primary safety and performance endpoints were met during the course of the study.

The TactiCath, which has been discussed in earlier issues of Medical Device Daily (most recently January 26, 2010) is the first and only force-sensing ablation catheter to give physicians a real-time, objective measure of contact force during the catheter ablation procedure.

Speaking at a session titled "Advanced Techniques Have the Potential to Improve the Results of Atrial Fibrillation Ablation," principal investigator Karl-Heinz Kuck, MD, of St. Georg Hospital (Hamburg, Germany) reiterated a statement he has made emphatically in the past two years. That is "this technology is the last missing piece of information that we need to improve our ability to treat AF."

He noted that the TOCCATA trial again supports the notion that there is a direct correlation between the catheter's contact force on the beating heart wall and safety and efficacy. Simply put, too much pressure on the wall can cause serious adverse events such as tamponade or perforations while inadequate pressure results in poor efficacy.

Endosense, which is solidly-backed by European venture capital, has recently commenced its EFFICAS I clinical trial in the Czech Republic. In addition, the company hopes to initiate its U.S. pivotal trial, which will be called TOCCA-STAR, in the second half of 2010.

Another company whose star is clearly rising in the AF field is privately-owned, venture capital-backed CardioFocus (Marlborough, Massachusetts). Its technology, which also addresses PAF, features a compliant balloon that can be maneuvered easily into the pulmonary veins, ablative laser energy and direct endoscopic visualization. Thus, the slogan that it has been using at its tradeshow booth: "See what you ablate, ablate what you see."

The company, which attained CE mark approval in June 2009, has made strong progress in the past year plus. 145 PAF patients treated since January 2009, with 76 patients treated in 2010. Of the 145 treated, 99 patients occurred in Europe at five centers, with 46 patients treated in the U.S. at eight centers. Its U.S. study feasibility is now nearly two-thirds enrolled and the company hopes to begin its U.S. pivotal trial in early 2011.

Some of the notable data to date includes 76% of patients that are arrhythmia-free six-to-twelve months following one ablation procedure, with no repeat procedure. 33 European patients were re-mapped about three months post-procedure regardless of their symptoms to determine whether electrical isolation was persistent. Impressively, of the 125 veins that were examined in this patient cohort, 90% of pulmonary veins were found to be electrically isolated.

In a talk here in a session on emerging new AF technologies, the company's U.S. principal investigator, Vivek Reddy. MD, from Mount Sinai Medical Center (New York) said that "while this ablation system may not be perfect it is a heckuva lot better than any other technology I have seen to date."

2010 Heart Rhythm Society

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