Vagus Nerve Stimulation Device Did Not Reduce Heart Failure Hospitalization or Mortality Rates

The implantable CardioFit device (BioControl Medical; New Hope, MN), intended to help heart failure (HF) patients by stimulating the vagus nerve did not significantly reduce the rates of HF hospitalization or all-cause mortality, according to results from the INOVATE-HF (Increase of Vagal Tone in Heart Failure) trial.

Co-principal investigator and lead author Michael Robert Gold, MD, PhD of the Medical University of South Carolina in Charleston presented the findings at the 2016 American College of Cardiology Annual Scientific Sessions & Expo (ACC), which were also simultaneously published in the Journal of the American College of Cardiology.

Dr Gold explained that the CardioFit device was designed to treat severe HF by stimulating the underactive parasympathetic nervous system. The device consists of a stimulation lead, stimulator, and standard pacemaker lead. The stimulation lead was designed for predominately unidirectional or efferent stimulation, B fiber stimulation, and minimal current leakage to reduce side effects.

A total of 707 patients from 85 centers across the United States were randomly assigned to receive the vagal nerve stimulation (VNS) device (n=436) or continued medical therapy (n=271) and were followed for months.

The primary end point of the study was all-cause composite death or first event for worsening HF. The secondary end points included changes in quality of life (QoL), New York Heart Association (NYHA) class, 6 minute walking distance, and left ventricular end-systolic volume index (LVESvi).

At an ACC press conference, Randall C. Starling, MD, MPH, FACC, professor of medicine and director of the Kaufman Center for Heart Failure, noted that the device was not activated immediately after implantation, but was turned on gradually over a 4-week period.

The all-cause mortality rate among the patients who received the VNS device was 30.3% compared with 25.8% in the control group (hazard ratio: 1.14; confidence interval: 0.86-1.53; P=.37).

Although the device did not lead to reduced hospitalization or mortality rates, the trial did show benefits for the secondary end points. First, the distribution of change in NYHA HF class differed more in the VNS group than the control group (P<.01). In addition, the Kansas City Cardiomyopathy Questionnaire QoL score increased by an average of 11.2 points in the VNS group compared with 6.9 points in the control group. The 6-minute hall walk distance also improved in the VNS group by an average 28.2 meters, while the average distance actually decreased in the control group by 4.6 meters (P<.01). Finally, the LVESvi  decreased in both groups, by 5.4 ml/m² in the VNS group and 2.8 ml/m² in the control group (P=.49).

“Stimulating the autonomic nervous system is much more complicated than stimulating the heart,” said Dr Gold.  He explained that given the outcomes from the secondary end point data, there may be patient subgroups [that] would benefit from this therapy. “We clearly need to know more about how to optimally stimulate these patients,” he added.

References

1. Gold RG, Starling RC. LBCT V. The effect of vagus nerve stimulation in heart failure: primary results of the Increase of Vagal Tone in Chronic Heart Failure (INOVATE-HF) trial. Presented at the 65^th Annual Scientific Sessions and Expo of the American College of Cardiology. April 2-4, 2016; Chicago, IL.
2. Gold MR, Van Veldhuisen DJ, Hauptman PJ, et al. Vagus nerve stimulation for the treatment of heart failure: the INOVATE-HF trial. J Am Coll Cardiol. 2016. doi: 10.1016/j.jacc.2016.03.525.