GAITHERSBURG, Maryland (Reuters) - U.S. health advisers rejected a Medtronic Inc (MDT.N) device for treating atrial fibrillation, a heart rhythm disorder that is a major cause of stroke, citing risks to safety.
A panel of outside experts for the Food and Drug Administration voted 8-2 that the risks of the Medtronic Cardiac Ablation System outweighed its benefits, especially given the high number of strokes among patients who got the device during clinical trials.
However, the panelists were unanimous that the device was effective for treating atrial fibrillation, which affects more than 2 million Americans and is the most prevalent heart rhythm disorder.
Their comments largely mirrored the review of the data by FDA staff earlier this week.
"There is a feeling that this system is effective, but there are concerns that the safety bars have not been met," said Dr. Clyde Yancy, panel chair and chief of cardiology at Northwestern University.
"To the sponsor, I hope what you've heard today is not a 'no,' but a 'not yet," he said, speaking to the company.
Medtronic shares fell 0.6 percent to $34.82 in after-market trading after closing at $35.02 on the New York Stock Exchange.
Atrial fibrillation describes the rapid and irregular contraction of the heart's upper two chambers, which allows blood to pool. This can form clots that travel to the brain and cause strokes.
The Medtronic device releases radiofrequency energy to destroy heart tissue that is causing the abnormal rhythms, in a process called ablation. This involves inserting a thin tube into a blood vessel, usually through a site in the upper leg or neck, then threading it through the body until it reaches the heart.
But in clinical trials, five people out of 176 had a stroke within a month of having been treated with the Medtronic device, and 38 people had at least one serious problem such as blocked veins that connect the lungs and heart, or swelling of the covering around the heart, according to the FDA.
Panel members were also concerned about data that suggested women seemed to not do as well as men when using the device. However, there were only 23 women using the device in trials, versus 115 men. A small sample size makes the data more difficult to interpret.
The company is seeking approval for its device as a treatment for persistent atrial fibrillation, which lasts for more than seven days or recurs for as long as four years.
Several panelists said the device should be approved if the company could conduct further trials to ensure its safety.
"I'm reminded of individuals that are truly grateful for being taken out of atrial fibrillation," said Scott Evans a biostatistician at the Harvard School of Public Health.
The company said just over half of patients have persistent atrial fibrillation, but there are no FDA-approved catheter ablation devices to treat this condition.
Dr. David Steinhaus, vice president and medical director at Medtronic, said the clinical trial was the first to test patients with persistent atrial fibrillation.
"It's really remarkable what this study has demonstrated in this population of patients," he said. He said Medtronic expects a final FDA decision in the next few months, and would discuss the next steps with the agency.
Results of the clinical trials for the device showed that 55.8 percent of patients had a normal heart rhythm within six months of using Medtronic's device, compared with 26.4 percent of patients who used the typical treatment of anti-arrhythmic drugs to treat atrial fibrillation.
Medtronic already received FDA approval in December 2010 to sell a different ablation device for treating paroxysmal atrial fibrillation, which is intermittent -- meaning it lasts for less than seven days, but it likely will recur.
Reporting by Anna Yukhananov; Editing by Gary Hill and Carol Bishopric