Autonomic Regulation Therapy via Left or Right Cervical Vagus Nerve Stimulation in Patients With Chronic Heart Failure: Results of the ANTHEM-HF Trial
Will autonomic regulation therapy (ART), via either left or right vagus nerve stimulation (VNS), improve systolic heart failure?
The ANTHEM-HF study cohort was comprised of 60 systolic heart failure patients (New York Heart Association [NYHA] class II-III, left ventricular ejection fraction [LVEF] ≤40%, LV end-diastolic dimension ≥50 mm and <80 mm) receiving optimal pharmacological therapy. The investigators randomly successfully implanted VNS systems on the left (n = 31) or right side (n = 29), and 59 were titrated over 10 weeks to a well-tolerated stimulation intensity.
The investigators reported that after 6 months of ART, the adjusted left-right differences in LVEF, LV end-systolic volume (LVESV), and LV end-systolic diameter (LVESD) were 0.2% [95% confidence interval (CI), -4.4 to 4.7], 3.7 ml [-7.0 to 14.4], and 1.3 mm [-0.9 to 3.6], respectively. In the combined population, absolute LVEF improved by 4.5% [2.4 to 6.6], LVESV improved by -4.1 ml [-9.0 to 0.8], and LVESD improved by -1.7 mm [-2.8 to -0.7]. Heart rate variability improved by 17 ms [6.5 to 28] with minimal left-right difference. Six-minute walk distance improved an average of 56 m [37 to 75]; however, improvement was greater for right-sided ART (77 m [49 to 105]). NYHA class improved in 77% of patients (baseline to 6 months). One patient died 3 days after an embolic stroke that occurred during implant. Common device-related adverse events after VNS titration were transient mild dysphonia, cough, and oropharyngeal pain, similar for left- and right-sided VNS.
The investigators concluded that chronic, open-loop ART via left- or right-sided VNS is feasible and well-tolerated in patients with systolic heart failure.
Systolic heart failure is accompanied by changes in the autonomic nervous system including increased sympathetic activity and withdrawal of parasympathetic activity. This is an important study because it suggests that stimulation of parasympathetic incrementally (in addition to sympathetic blockade) improves LV dimensions and exercise tolerance in systolic heart failure patients. The device has a good safety profile and is well tolerated. The next step would be to conduct a large randomized trial to confirm whether chronic low-amplitude VNS improves LV function, exercise tolerance, and survival.
Keywords: Exercise Tolerance, Stroke, Stroke Volume, Pain, Cough, Heart Rate, Heart Failure, Systolic, Autonomic Nervous System, ESC Congress
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