CryoCor hopes its lead in the race to gain an atrial fibrillation indication for an ablation catheter will translate into a market advantage, but first it will need to change what it says are misperceptions among some physicians about the limitations of cryoenergy.
In August, San Diego-based CryoCor became the first company to complete enrollment in a randomized pivotal trial for an ablation catheter to treat atrial fibrillation. After one-year follow-up is complete, the firm plans to submit a PMA in the latter part of 2008.
The CryoCor cryoablation system disrupts cardiac arrhythmias using extreme cold to create lesions in cardiac tissue. It was approved in August to treat atrial flutter (1"The Gray Sheet" Aug. 6, 2007, p. 16).
Today, almost all catheter ablations for atrial fibrillation are performed off-label using radiofrequency energy-based catheters that FDA has approved for general cardiac ablation or treatment of other forms of arrhythmia.
Although no ablation device is approved specifically for atrial fibrillation, the market CryoCor ultimately hopes to tap is already growing rapidly. According to CEO Edward Brennan, there were over 40,000 atrial fibrillation ablation procedures done in 2007 compared with 26,000 in 2006.
Brennan predicts that procedure volume will expand even more rapidly once a specific atrial fibrillation indication is approved, particularly in hospitals with physicians who may not be as aggressive as those in university or training centers where ablation is already the standard of care.
The exec notes that approval could both help with reimbursement and reduce liability exposure. "All you have to do is have a bad adverse event occur with a non-approved device and you're going to get a backlash," he said.
Bruce Lindsay, M.D., director of cardiac electrophysiology at the University of Washington in St. Louis, thinks that for ablation catheters already on the market, a label specific to atrial fibrillation will have little effect. "Anybody who wants to do [atrial fibrillation ablation] can use the existing tools," he said in an interview.
"That's why they haven't been specifically tested for atrial fibrillation - because physicians have just gone ahead and used them," noted Lindsay, who also is the current president of the Heart Rhythm Society, the professional society for electrophysiologists.
Cryo May Have Hurdle To Jump With Docs
CryoCor has just begun to roll out its ablation catheter under the atrial flutter indication with a sales force hired in December and January.
According to CFO Gregory Tibbitts, CryoCor is trying to change the belief among some physicians, including Lindsay, that cryoablation procedures take much longer than ablation with radiofrequency energy.
Part of the problem, according to Tibbitts, is that a competing cryoablation catheter on the U.S. market since 2003, CryoCath's Freezor, is less powerful and takes about four minutes to create a smaller lesion than that made in less than a minute with RF.
"The thing we are trying to do to change ... the minds of physicians and investors is [show] that there is a superior cryoablation catheter that is finally available," he said.
CryoCor's system makes lesions the same size as the newest RF catheters. Although each lesion still takes two minutes to create, the overall procedure lengths are comparable to RF procedures because of other benefits for catheter placement, Brennan says.
What Brennan believes really sets CryoCor apart from RF ablation catheters is its safety profile, particularly for ablations across the heart's back wall, which butts up against the esophagus. One concern with heat energy is the potential for a rare, life threatening complication called an atrial-esophageal fistula.
According to Brennan, cryoablation does not appear to cause this complication. Even if some physicians use RF catheters to ablate other areas of the heart, CryoCor believes many will switch to cryoablation for back-wall lesions.
Firms with RF cardiac ablation catheters already on the market include Boston Scientific, St. Jude Medical, Johnson & Johnson/Biosense Webster and C.R. Bard.
A-Fib Label Critical For Balloon Catheter Ablation
While some analysts believe FDA approval of an atrial fibrillation indication could expand the market, it remains to be seen how large the effect could be for individual manufacturers.
"It's less important for a company whose product can be used for multiple purposes, because it doesn't really matter what the FDA says. It can be used anyway," Lindsay said. However, it would be "a big deal" to a company with a product designed only for atrial fibrillation.
Up-and-coming devices designed specifically to treat atrial fibrillation include balloon ablation catheters. They create a circular lesion around the pulmonary vein all at once, while existing catheters require physicians to string together multiple lesions to create the same treatment pattern.
Three manufacturers currently running randomized pivotal trials each have balloon catheter technologies based on different ablation energies (2"The Gray Sheet" Jan. 23, 2006, p. 9).
ProRhythm began a 240-patient trial called FocusAF in April 2006 for its HIFU high-intensity focused ultrasound catheter.
CryoCath started its 240-patient STOP AF trial for the Arctic Front cryo-balloon catheter in October. As of December, 162 patients had been enrolled, on track for April 2008 completion. CryoCath says it anticipates FDA approval of the device in late 2009.
CardioFocus' 200-patient ENABLE trial for its Endoscopic Ablation System began in March 2007. The device creates lesion arcs with a diode laser. According to CEO Stephen Sagon, enrollment is expected to go into 2009.
All three trials have one-year follow up and randomize patients to device treatment or drug therapy.
As ablation becomes more accepted as a therapy for atrial fibrillation, however, firms are increasingly finding patients unwilling to be randomized into drug treatment (3"The Gray Sheet" Oct. 1, 2007, p. 9).
Sagon said FDA is aware of the issue and is allowing incremental changes to trial protocols for firms still enrolling patients to relax the inclusion and exclusion criteria.
"Anyone who is not done with the study at this point knows how challenging it is to continue to enroll," noted CryoCor's Brennan.
CryoCor Touts Flexibility Of Next-Gen Quantum
CryoCor plans to begin a feasibility trial in the second quarter for its next-generation Quantum cryoablation catheter.
While most ablation catheters have relatively short ablation tips, measuring less than a centimeter, Quantum has a section that freezes a four- or five-centimeter length. The ablative section can be configured to form lesions in arcs, semicircles or long straight lines.
"We think that it has increased flexibility ... and provides a tool that actually has application in a broader set of patients than perhaps the balloons that are being evaluated," Brennan explained.
Although CryoCor has not projected a target approval date for the next-gen device, it believes the Quantum pivotal trial will be relatively quick to complete because data from the trial of its current system could serve as the control.
Separately, CryoCor announced last June a collaboration with Boston Scientific to co-develop a cryo-console to power Boston Scientific's in-house ablation balloon to treat atrial fibrillation (4"The Gray Sheet" July 2, 2007, In Brief).
CryoCor also is embroiled in patent litigation with cryo-competitor CryoCath. Montreal-based CryoCath filed suit against CryoCor in October for infringement of console patents. CryoCor countersued Jan. 16. Both firms are seeking injunctive relief.
- Chloe Taft
