AtriCure Inc's device for treating a heart rhythm disorder is safe and effective, but its trial size and design raise some concerns, U.S. Food and Drug Administration researchers said.
AtriCure Synergy Ablation System is approved for ablation of heart tissue during surgery. It uses radiofrequency energy to remove or destroy problem-causing heart tissue.
The device maker is now hoping to expand the approved label to indicate the device should also be used to restore normal heart rhythm in patients with atrial fibrillation during open-heart surgery.
Atrial fibrillation is the most prevalent heart rhythm disorder, in which the heart's upper two chambers contract rapidly and irregularly and don't properly pump blood into the lower chambers. The condition affects more than 2 million Americans and is a major cause of stroke.
Without a specific indication for atrial fibrillation, AtriCure said it has been prohibited from training physicians to use the device for the abnormal heart rhythm or to discuss the condition in any way.
The latest trial of AtriCure's ablation device "appears to have succeeded" to safely and effectively treat atrial fibrillation during cardiac surgery, but only if all enrolled patients are considered, Food and Drug Administration researchers said in documents released on Monday.
Some patients selected for the trial had recurring but intermittent (paroxysmal) heart rhythm problems, meaning they may be healthier than those with more advanced forms of the heart condition. Excluding those so-called paroxysmal patients, the trial met neither the safety, nor the effectiveness goals, researchers said.
In the pivotal clinical study, 55 patients were treated in surgery, four of which were paroxysmal. The company stopped enrolling at 55, which is a minimum, because of how hard it was to find participants. Acknowledging the complex task of finding willing and appropriate participants for the trial, FDA reviewers said that had the company enrolled more non-paroxysmal patients, the trial may have yielded different results.
"(AtriCure) is targeting a population of patients with non-paroxysmal (atrial fibrillation). Evaluating only non-paroxysmal patients reduces the already-small ABLATE (trial) data set by 4," they wrote. "Not only does this have possible implications for interpretation of data in the final analyses, but also for the course of study progress."
Shares of AtriCure tumbled on Nasdaq, falling 12.6 percent to $10.16, in contrast with the S&P Health Care Equipment Sub-Industry Index, which rose 1.9 percent.
While such ablation devices are still a relatively small part of the multibillion atrial fibrillation market, analysts expect it to grow.
(Reporting by Alina Selyukh in Washington; editing by Carol Bishopric)