Phrenic Nerve Stimulation in Sleep Apnea | Journal Scan

Study Questions:

Can intermittent unilateral phrenic nerve stimulation improve central sleep apnea (CSA) in heart failure?


Heart failure patients were recruited from multiple centers between 2010 and 2012, into the Chronic Evaluation of Respicardia Therapy prospective nonrandomized feasibility and efficacy study. Recruitment took place among patients with apnea–hypopnea indexes (AHIs) ≥20, with at least one half being central apneas. Patients were excluded if ≥20% apneas were primarily obstructive or heart failure was not stable on medical therapy. Systolic and diastolic heart failure were included. Other exclusions were severe lung disease, creatinine ≥2.5 mg/dl, or any cardiac procedure within the last 3 months. Polysomnograms were done overnight and attended according to standard guidelines before and after implantation. The Remedē System (Respicardia, Inc., Minnetonka, MN) was placed transvenously in the right brachiocephalic vein or left pericardiophrenic vein to provide neurostimulation of the adjacent phrenic nerve, resulting in diaphragmatic stimulation. Sensing of respiration was done by a transvenous lead in the azygous vein. Leads are connected to a generator similar to the size of a pacemaker and placed subcutaneously. The system prevents apneic events by determining appropriate therapy based on device sensors. Device- and procedure-related events were evaluated. The primary endpoint was a change in AHI at 3 months.


A total of 57 patients enrolled and eight left the initial hospital without an implanted device, most due to anatomic issues. Two patients withdrew before 3 months. Endpoint data were performed on 47 patients. The average age was 65.9 ± 9.6 years, including: 89% men, 74% hypertension, 30% atrial fibrillation, and 66% coronary artery disease. Heart failure with ejection fraction was found in 9%, but most with heart failure were class II or III and 53%, or the cohort had a concomitant cardiac device. Serious device or procedure events occurred in 26% through 6 months, predominantly due to lead repositioning early in the study. There was a 55% reduction in AHI from baseline to 3 months (49.5 ± 14.6 episodes/hour vs. 22.4 ± 13.6 episodes/hour of sleep; p < 0.0001; 95% confidence interval for change, -32.3 to -1.9).


The authors concluded that phrenic nerve stimulation performed though a transvenous approach is a novel, safe, and efficacious method to treat CSA.


This is a small unblinded, open-label, uncontrolled trial, which may lend itself to bias. However, the observed statistical reduction in AHI is an objective endpoint, adding credibility to the conclusions. The number of adverse events seems high, but is comparable to other cardiac devices when initially introduced. Limitations include size and lack of control group. If these findings are reproduced in larger prospective, randomized, controlled trials, treatment of CSA with the Remedē System may offer clinicians another tool to provide symptom relief in this population.

Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Prevention, Atherosclerotic Disease (CAD/PAD), Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure, Chronic Heart Failure, Hypertension, Sleep Apnea

Keywords: Apnea, Atrial Fibrillation, Brachiocephalic Veins, Coronary Artery Disease, Coronary Disease, Heart Failure, Heart Failure, Systolic, Heart Failure, Diastolic, Hypertension, Phrenic Nerve, Polysomnography, Sleep Apnea, Central, Sleep Apnea Syndromes, Systole

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