Phrenic nerve stimulator shows heart failure benefits

DALLAS– Heart failure patients with central sleep apnea who received treatment with a transvenous phrenic nerve–stimulating device showed dramatic improvement in their global self-assessment, compared with control patients, in a subgroup analysis of 80 patients enrolled in the device’s pivotal trial.

Among 35 patients with heart failure enrolled in the remedē System pivotal trial and treated for 6 months with phrenic nerve stimulation, 57% reported that they had “markedly” or “moderately” improved, compared with a 9% rate for this self-rating among 44 control heart failure patients in the trial, a statistically significant difference, Lee R. Goldberg, MD, said at the annual scientific meeting of the Heart Failure Society of America.

^{Mitchel L. Zoler/Frontline Medical News}

Dr. Lee Goldberg

Further analysis focused on echocardiographic examinations after 12 months in 23 of the heart failure patients who entered the study with a left ventricular ejection fraction of 45% or less and received 12 months of phrenic nerve stimulation. The average LVEF rose in these patients from 30% at baseline to 35%, a statistically significant difference, and left ventricular end systolic volume fell by an average of almost 11 mL from baseline, a difference just short of statistical significance, findings Dr. Goldberg called “a little exciting.”

“It is very encouraging to see some evidence for ventricular remodeling,” commented Lynne W. Stevenson, MD, professor of medicine and a heart failure specialist at Vanderbilt University in Nashville, Tenn.

Dr. Lynne W. Stevenson

The FDA approved the use of this device for the treatment of moderate to severe central sleep apnea on Oct. 6. “I think we would use it” in heart failure patients with intolerable symptoms from central sleep apnea, Dr. Goldberg said in an interview during the meeting.

“There is a tight connection between sleep-disordered breathing, sleep apnea, heart failure, and cardiovascular disease, and we have been pretty aggressive in trying to treat the sleep apnea. Even if phrenic nerve stimulation just improves patients’ quality of life and is neutral for other outcomes,” it would be reasonable to offer it to patients, he said. “But many of us think there is a bigger connection that results in a therapeutic benefit [to heart failure patients] by treating their central sleep apnea.”

The pivotal trial enrolled a total of 151 patients with central sleep apnea at 31 centers in Germany, Poland, and the United States who were selected based on having an apnea-hypopnea index of at least 20 events per hour. All participants received a transvenous phrenic nerve–stimulator implant, and then randomization assigned 73 patients to have the device turned on for the first 6 months while 78 device recipients had their devices left off to serve as controls. The study’s primary efficacy endpoint was the percentage of patients having at least a 50% cut in their apnea-hypopnea index, which happened in 51% of evaluable patients in the active treatment arm and in 11% of the evaluable controls. The primary results were published last year (Lancet. 2016 Sep 3;388[10048]974-82).

“We hope this treatment will have the collateral effect of improving cardiovascular disease outcomes, but we don’t know that yet. The initial target will be patients with apnea-hypopnea episodes that affect their quality of life,” Dr. Goldberg said.

The apparent safety of this approach for treating central sleep apnea may relate to its mechanism of action, he suggested. The mortality-boosting effect of adaptive servo-ventilation may correlate with the positive pressure it creates in a patient’s chest that perhaps causes myocardial stress or hemodynamic problems. In contrast, phrenic nerve stimulation produces diaphragm motion that mimics normal breathing and creates negative chest pressure. “A lot of hypothesis generation needs to happen to better understand the underlying physiology,” Dr. Goldberg conceded.

At the end of the 6-month period that compared active treatment with control, the heart failure subgroup also showed statistically significant benefits from treatment for several sleep metrics, including apnea-hypopnea index, the central apnea index, and oxygen desaturation, and also for daytime sleepiness measured on the Epworth Sleepiness Scale. After 12 months on active treatment, patients also showed a significant improvement over baseline in their score on the Minnesota Living With Heart Failure Questionnaire, Dr. Goldberg reported.

The trial was sponsored by Respicardia, the company developing the remedē System. Dr. Goldberg has been a consultant to and has received research funding from Respicardia. Dr. Stevenson had no relevant disclosures.

mzoler@frontlinemedcom.com

On Twitter @mitchelzoler