Vagus Nerve Stimulation Provides Multiyear Improvements in Autonomic Function and Cardiac Electrical Stability in the ANTHEM-HF Study

Background: Patients with heart failure with reduced left ventricular ejection fraction (LVEF) (HFrEF) experience long-term deterioration of autonomic function and cardiac electrical stability linked to increased mortality risk. The Autonomic Neural Regulation Therapy to Enhance Myocardial Function in Heart Failure (ANTHEM-HF) trial reported improved heart rate variability (HRV) and heart rate turbulence (HRT) and reduced T-wave alternans (TWA) after 12 months of vagus nerve stimulation (VNS). We investigated whether the benefits of chronic VNS persist in the long term.

Methods and results: Effects of chronic VNS on heart rate, HRV, HRT, TWA, R-wave and T-wave heterogeneity (RWH, TWH), and nonsustained ventricular tachycardia (NSVT) incidence were evaluated in all ANTHEM-HF patients with ambulatory ECG data at 24 and 36 months (n = 25). Autonomic markers improved significantly at 24 and 36 months compared to baseline [heart rate, square root of the mean squared differences of successive normal-to-normal intervals (rMSSD), standard deviation of the normal-to-normal intervals (SDNN), HF-HRV, HRT slope, P < 0.05]. Peak TWA levels remained reduced at 24 and 36 months (P < 0.0001). Reductions in RWH and TWH at 6 and 12 months persisted at 24 and 36 months (P < 0.01). NSVT decreased at 12, 24, and 36 months (P < 0.025). No sudden cardiac deaths, ventricular fibrillation, or sustained ventricular tachycardia occurred.

Conclusion: In symptomatic patients with HFrEF, chronic VNS appears to confer wide-ranging, persistent improvements in autonomic tone (HRV), baroreceptor sensitivity (HRT), and cardiac electrical stability (TWA, RWH, TWH).