Vagus Nerve Implant Fails to Fix Heart Failure

By Samuel K. MoorePosted 2 Sep 2014 | 16:38 GMT

Illustration: Getty Images

Implanted devices that stimulate the vagus nerve in the neck help

with epilepsy and depression but not, it seems, heart failure.

Attempts to use electronic implants to treat heartfailure by stimulating one of a pair of nerves in theneck led to mixed results according to researchpresented this week at the

, in Barcelona. BostonScientific's large, randomized trial

. But Cyberonics, which pioneered theuse of such stimulators to combat epilepsy anddepression, ran

, according to.

2014 European Societyof Cardiology (ESC) Congress(http://www.escardio.org/congresses/esc-2014/PAges/welcome.aspx)

failed to meetits key goals(http://www.escardio.org/about/press/press-releases/esc14-barcelona/Pages/hotline-one-nectar.aspx)

a smaller trial without controlsthat succeeded(http://www.reuters.com/article/2014/09/01/us-health-heart-cyberonics-idUSKBN0GW1MJ20140901)Reuters

Both trials used implanted electric stimulators that attached to one of a pair of key nerves in the neck, thevagus nerve. The nerve connects the brain to the heart, stomach, and other organs. It's a key target formedical device developers because it allows convenient access to the brain to treat disorders of that organ,such as

, as well as to gut organs to treat other problems, such as .

epilepsy and depression (http://spectrum.ieee.org/biomedical/diagnostics/psychiatrys-shocking-new-tools) obesity(http://spectrum.ieee.org/biomedical/devices/startups-making-electronic-implants-to-treat-obesity)

Heart failure, the inability of the heart to pump enough blood to satisfy the body's needs, has also been onthe list of targets. The failure of Boston Scientific's trial was a big surprise to its leaders. "There is robust pre-clinical data showing the benefit of [vagus nerve stimulation], but the NECTAR-HF trial failed todemonstrate a successful clinical translation of this protocol," Faiez Zannad an investigator in the trial atl'Institut Lorrain du Coeur et des Vaisseaux Louis Mathieu, in Vandoeuvre-lès-Nancy, France, said in a pressrelease.

Boston Scientific was hoping to see a key marker of improvement—a decrease in the size of the left ventriclewhen it's fully contracted. They were also looking for other heart dimension measurements, as well asimprovements in exercise capacity and in levels of the hormone tied to heart failure.

The results were especially disappointing because of the care used in designing the study. 96 heart failurepatients were recruited from across Europe, and all received implants for their right vagus nerve. Two-thirdshad the stimulator turned on, while one third acted as controls with the stimulator off. All received the best

standard treatment for heart failure during the following six months. After that point the controls, too, hadthe stimulator switched on.

Zannad suggested that the failure to see results may have been because the treatment group was alreadypretty well managed using standard medical therapies or because six months is too short a time period. Theamount of current delivered might also have been too low.

The Cyberonics trial also followed patients for six months, but it was less convincing because it lacked acontrol group that received implants but no stimulation. Together, the 60 patients averaged a 4.5 percentimprovement in left ventricular ejection fraction—a measure of how much blood makes it out of the leftventricle when it contracts.

"I think, at six months, that [4.5 percent improvement] is a very impressive achievement," study leader from the

University of Minnesota .

Inder Anand (http://www.worldheartfailure.org/WHFS/about-us/board/inder-s-anand/)told reporters (http://www.reuters.com/article/2014/09/01/us-health-heart-

cyberonics-idUSKBN0GW1MJ20140901)

Clearly, more clinical trials will be needed to see if this therapy can make a difference. But, following thefailure of Boston Scientific's trial, whether or not to pay for that research will likely be a more difficultquestion.