Phrenic Nerve Stimulation Holds Up for Central Sleep Apnea

Five-year data supported the long-term safety and effectiveness of transvenous phrenic nerve stimulation (TPNS) for central sleep apnea (CSA), investigators said.

CSA severity decreased in patients after Remede device implantation and stayed that way out to 5 years, according to a group led by Maria Rosa Costanzo, MD, of Advocate Heart Institute in Chicago:

• More than half of patients maintained improvement of apnea hypopnea index (AHI) at both 1 year and 5 years
• Central apnea index remained under 1 event per hour at 1 year and 5 years alike versus a baseline of roughly 23 events per hour
• Over half of patients achieved sustained improvement in arousals through 5 years
• Arousals totaled 19 per hour at both 1 year and 5 years, down from a baseline of roughly 39 arousals per hour
• Daytime sleepiness scores on the Epworth scale stayed at a median 6 points at 1 and 5 years, down from 9 points at baseline

There were no deaths attributed to the procedure or device, but 14% of patients experienced a serious adverse event, Costanzo's team reported in a poster presented at this year's virtual meeting of the Heart Failure Society of America.

Of note were four late events (beyond 3 years): two stimulation lead component failures requiring surgical lead replacement, one lead dislocation, and one implant site infection following an implantable pulse generator replacement procedure.

"TPNS is a viable long-term treatment option for adults with moderate to severe CSA," the authors concluded.

Costanzo and colleagues had demonstrated the safety and effectiveness of Remede therapy in a randomized pivotal trial of 151 people. As a result, FDA approved the Remede device for moderate-to-severe CSA in 2017.

Remede is a small implantable device that regularly stimulates a phrenic nerve to induce diaphragmatic contraction, creating negative intrathoracic pressure similar to normal breathing. The implant is placed below the collar bone, with a transvenous stimulator lead extending to the target nerve.

The post-approval analysis included the 53 people in the treatment arm who had results out to 5 years. Despite the follow-up population being less than half of the original, the 5-year data are "important, as the procedure looks to have sustained effects," commented Atul Malhotra, MD, of UC San Diego Health.

Study participants underwent central laboratory-scored polysomnography.

Outcomes with the device were consistent for the subgroup of heart failure patients. Kaplan-Meier estimated survival was 78% at 5 years in the Remede treatment arm and 68% in the heart failure subgroup, according to Costanzo's group.

However, survivor bias may be at play, given that this subgroup included just 22 heart failure patients out of the 80 that were included at baseline, Malhotra suggested. "The follow-up group may be relatively healthy since the sickest ones may be deceased."

Nevertheless, "it is good to raise awareness and draw attention to sleep issues in heart failure as they are very common and often overlooked," he told MedPage Today.

"The device does not work for obstructive apnea, so the procedure is ideally done with pure CSA, which we do not see very commonly. Patients with mixed apnea or with components of obstructive and central apnea may still require CPAP [continuous positive airway pressure] even if the central apnea is addressed," Malhotra noted.

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