Autonomic Regulation Therapy Suppresses Quantitative T-Wave Alternans and Improves Baroreflex Sensitivity in Heart Failure Patients Enrolled in the ANTHEM-HF Study.

Autonomic regulation therapy (ART) with chronic vagus nerve stimulation (VNS) improves ventricular function in chronic heart failure patients, but its effects on quantitative T-wave alternans (TWA), ventricular tachycardia (VT), baroreflex sensitivity, and autonomic tone remained unknown.Effects on TWA, a marker of risk for life-threatening arrhythmias, heart rate turbulence (HRT), an indicator of baroreflex sensitivity, heart rate variability (HRV), and VT incidence were studied in 25 patients with chronic, symptomatic heart failure and reduced ejection fraction enrolled in ANTHEM-HF Study (NCT01823887).24-hour ambulatory electrocardiogram recordings made prior to ART system (Cyberonics, Houston, TX) implantation involving the left or right vagus nerve and after 6 and 12 months of chronic therapy (10 Hz, 250-μsec pulse width, maximum tolerable current amplitude after 10 weeks of titration) at low- (<2 mA, n=10) or high-intensity (≥2mA, n=15) stimulation levels were analyzed.At 12 months, peak TWA levels were reduced from 71.0±4.6 to 50.5±1.8 μV (p<0.0001). The number of patients with severely abnormal TWA (≥60 μV) was reduced from 17 to 4 (p<0.0005) and patients with non-sustained VT decreased from 11 to 3 (p<0.025). HRT slope (p<0.025) and HF (p=0.05) and rMSSD HRV (p=0.013) increased. Mean heart rate derived from 24-hour Holter ECG declined from 77±2 to 69±2 beats/min (p=0.0002). HRT onset was unchanged.Chronic ART in patients with symptomatic heart failure improves cardiac electrical stability, as reflected by reduced TWA levels and heart rate, suppresses VT, and increases baroreceptor sensitivity. These observations deserve study in a larger population.