Persistent Autonomic Engagement and Cardiac Control After Four or More Years of Autonomic Regulation Therapy Using Vagus Nerve Stimulation.

Introduction: Although heart failure (HF) outcomes have improved dramatically with the use of guideline directed medical therapy and implantable devices, the overall prognosis of patients with HF and reduced ejection fraction (HFrEF) remains poor. Autonomic Regulation Therapy (ART) using chronic vagus nerve stimulation (VNS) has been evaluated in the ANTHEM-HF study, using changes in heart rate (HR) dynamics as a biomarker of autonomic nervous system engagement and cardiac control to guide VNS titration. ART was associated with sustained improvement in cardiac function and HF symptoms in patients with HFrEF and persistent HF symptoms despite guideline-directed medical therapy (GDMT). We sought to determine whether the responsiveness of the autonomic nervous system to ART, as reflected in HR response to vagus stimulation during the VNS duty cycle, is maintained after long-term chronic VNS administration. Methods: Fifteen patients with HFrEF and implanted with a VNS systems in the ANTHEM-HF study were evaluated after 4.7 ± 0.3 years (range: 4.0-5.0 years) of chronic ART. ECG electrodes were placed on each patient's wrists, and ECG rhythm strips were recorded. Instantaneous HR time series was computed at each patient's chronically programmed VNS intensity and during progressively increasing VNS intensity. HR during active stimulation (on-time) was compared to HR just prior to initiation of each stimulation cycle (off-time). Results: Persistent autonomic engagement was observed in a majority of patients (11 of 15, 73%) after chronic ART for four or more years. The average magnitude of HR reduction during ART on-time in all patients was 2.4 ± 3.2 bpm at the chronically programmed VNS pulse parameter settings. Conclusion: Autonomic responsiveness to VNS persists in patients with HFrEF who received chronic ART for up to 5 years as a supplement to GDMT. This suggests that the effects of ART on autonomic engagement and cardiac control remain durable over time. Clinical Trial Registration: [ClinicalTrials.gov], identifier [#NCT01823887, CTRI registration #CTRI/2012/05/002681].

Therapeutic responsiveness to vagus nerve stimulation in patients receiving beta-blockade for heart failure with reduced ejection fraction.

BACKGROUND: The effect of beta-blockade (BB) on response to vagus nerve stimulation (VNS) has not been reported in patients with heart failure and reduced ejection fraction (HFrEF). In the ANTHEM-HF Study, 60 patients received chronic cervical VNS. Background pharmacological therapy remained unchanged during the study, and VNS intensity was stable once up-titrated. Significant improvement from baseline occurred in resting 24-hour heart rate (HR), 24-hour HR variability (SDNN), left ventricular EF (LVEF), 6-minute walk distance (6MWD), and quality of life (MLWHFS) at 6 months post-titration. We evaluated whether response to VNS was related to percentage of target BB dose (PTBBD) at baseline. METHODS: Patients were categorized by baseline PTBBD, then analyzed for changes from baseline in symptoms and function at 6 months after VNS titration. RESULTS: All patients received BB, either PTBBD ≥ 50 % (16 patients, 27 %; group 1) or PTBBD < 50 % (44 patients, 73 %; group 2). Heart rate, systolic blood pressure, LVEF, use of ACE/ARB, and use of MRA were similar between the two groups at baseline. Six months after up-titration, VNS reduced HR and significantly improved SDNN, LVEF, 6MWD, and MLWHFS equally in both groups. CONCLUSIONS: In the ANTHEM-HF study, VNS responsiveness appeared to be independent of the baseline BB dose administered.

Long-term Follow-Up of Patients with Heart Failure and Reduced Ejection Fraction Receiving Autonomic Regulation Therapy in the ANTHEM-HF Pilot Study.

BACKGROUND: The ANTHEM-HF pilot study was an open-label study that evaluated the safety and feasibility of autonomic regulation therapy (ART) utilizing cervical vagus nerve stimulation (VNS) for patients with chronic HF with reduced EF (HFrEF). Patients in NYHA class II-III with EF ≤40% (n = 60) received ART for 6 months post-titration. ART was associated with sustained improvement in left ventricular (LV) function and HF symptoms at 6 and 12 months. METHODS: Continuously cyclic VNS was maintained to determine longer-term safety and chronic effects of ART. Echocardiographic parameters and HF symptoms were assessed throughout a follow-up period of at least 42 months. RESULTS: Between 12 and 42 months after initial titration, there were no device-related SAEs or malfunctions. There were 10 SAEs adjudicated to be unrelated to VNS, including 5 deaths. There were 6 non-serious adverse events that were adjudicated to be device-related (2 oropharyngeal pain, 1 implant site pain, 2 voice alteration, and 1 hoarseness). At 42 months, there was significant improvement from baseline in LVEF, NYHA class, 6-min walk distance, and MLHFQ score. However, these improvements at 42 months were not significantly different from mean values at 6 and 12 months. CONCLUSIONS: In a 42-month follow-up, ART was durable, safe, and was associated with beneficial effects on LVEF and 6-min walk distance. Long term, chronic, open-loop ART continued to be well-tolerated in patients with HFrEF. The open label, randomized, controlled, ANTHEM-HFrEF Pivotal Study is currently underway to further evaluate ART in patients with advanced HF.

Baseline NT-proBNP and responsiveness to autonomic regulation therapy in patients with heart failure and reduced ejection fraction.

BACKGROUND: Recent heart failure studies have associated lower baseline natriuretic peptide levels with improved morbidity/mortality outcomes during pharmaceutical treatment, and better clinical outcomes during neuromodulation (NM) with carotid nerve plexus stimulation for HFrEF when NT-proBNP < 1600 pg/ml. Whether baseline NT-proBNP is associated with HFrEF responsiveness to NM using vagus nerve stimulation (VNS) has not been examined. Hence, we evaluated the interaction of baseline NT-proBNP with changes in symptoms and function that occurred during chronic VNS in the ANTHEM-HF study. METHODS: A repeated measures, generalized-estimating, equations model evaluated the relationship of baseline NT-proBNP values above and below 1600 pg/ml to symptomatic and functional responses in ANTHEM-HF. RESULTS: Median (interquartile range; maximum) NT-proBNP was 868 (322, 1875; 14,656) pg/ml (N = 58). Heart rate (HR), HR variability (SDNN), 6-minute walk distance, MLWHF mean score, and NYHA improved significantly, independent of baseline NT-proBNP. While there was a statistical interaction between baseline NT-proBNP and better LVEF improvement during VNS, LVEF improved overall in the study cohort (N = 60; 32 ± 7 to 37 ± 10%; p = 0.0042), and in those patients whose baseline NT-proBNP was below the median baseline NT-proBNP value (n = 29; 36 ± 6 to 42 ± 10%; p < 0.0025)] or above this value (n = 29; 29 ± 7 to 32 ± 9%; p < 0.05). CONCLUSIONS: In ANTHEM-HF, overall symptomatic and functional improvement during chronic VNS was independent of baseline NTproBNP. These are preliminary and hypothesis-generating findings, and the reason for a differing interaction between baseline NT-proBNP and response to CNPS and VNS remains unclear. It is anticipated that the ongoing ANTHEM-HFrEF Pivotal Study of VNS will provide additional insight.

Background pharmacological therapy in the ANTHEM-HF: comparison to contemporary trials of novel heart failure therapies.

AIMS: Clinical trials of new heart failure (HF) therapies administer guideline-directed medical therapy (GDMT) as background pharmacologic treatment (BPT). In the ANTHEM-HF Pilot Study, addition of autonomic regulation therapy to GDMT significantly improved left ventricular function, New York Heart Association (NYHA) class, 6 min walk distance, and quality of life in patients with HF with reduced ejection fraction (HFrEF). A post hoc analysis was performed to compare BPT in ANTHEM-HF with two other trials of novel HF therapies: the PARADIGM-HF study of sacubitril-valsartan and the SHIFT study of ivadrabine. All three studies evaluated patients with HFrEF, and the recommendations for use of GDMT were similar. A left ventricular ejection fraction ≤40% was required for entry into ANTHEM-HF and PARADIGM-HF and ≤35% for SHIFT. NYHA 2 or 3 symptoms were required for entry into ANTHEM-HF, and patients with predominantly NYHA 2 or 3 symptoms were enrolled in PARADIGM-HF and SHIFT. METHODS AND RESULTS: Data on BPT were obtained from peer-reviewed publications and the public domain. Pearson's χ2 test was used to evaluate differences in proportions, and Student's unpaired t-test was used to evaluate differences in mean values. The minimum period of stable GDMT required before randomization was longer in ANTHEM-HF: 3 months vs. 1 month in PARADIGM-HF and SHIFT, respectively. When compared with PARADIGM-HF and SHIFT, more patients in ANTHEM-HF received beta-blockers (100% vs. 93% and 89%, P < 0.04 and P < 0.007) and mineralocorticoid receptor antagonists (75% vs. 55% and 61%, P < 0.002 and P < 0.03). More patients in PARADIGM-HF received an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker than in ANTHEM-HF or SHIFT (100% vs. 85%, P < 0.0001, and 100% vs. 91%, P < 0.001), which was related to PARADIGM's design. When beta-blocker doses in ANTHEM-HF and SHIFT were compared, significantly fewer patients in ANTHEM-HF received doses ≥100% of target (10% vs. 23%, P < 0.02), and fewer patients tended to receive doses ≥50% of target (17% vs. 26%, P = 0.11). When ANTHEM-HF and PARADIGM-HF were compared, more patients in ANTHEM-HF tended to receive doses ≥100% of target (10% vs. 7%, P = 0.36), and fewer patients tended to receive doses ≥50% of target (17% vs. 20%, P = 0.56). CONCLUSIONS: Background treatment with GDMT in ANTHEM-HF compared favourably with that in two other contemporary trials of new HF therapies. The minimum period of stable GDMT required before randomization was longer, and GDMT remained unchanged for the study's duration. These findings serve to further support the potential role of autonomic regulation therapy as an adjunct to GDMT for patients with HFrEF.

Extended Follow-Up of Patients With Heart Failure Receiving Autonomic Regulation Therapy in the ANTHEM-HF Study.

OBJECTIVE: Evaluate the effects of a novel autonomic regulation therapy (ART) via vagus nerve stimulation (VNS) in patients with chronic heart failure (HF) and reduced left ventricular ejection fraction during a 12-month follow-up period. METHODS: The Autonomic Regulation Therapy for the Improvement of Left Ventricular Function and Heart Failure Symptoms (ANTHEM-HF) study enrolled 60 subjects with New York Heart Association class II-III HF and low left ventricular ejection fraction (≤40%), who received open-loop ART using VNS randomized to left or right cervical vagus nerve placement and followed for 6 months after titration to a therapeutic output current (2.0 ± 0.6 mA). Patients received chronic stimulation at a frequency of 10 Hz and pulse duration of 250 µsec. Forty-nine subjects consented to participate in an extended follow-up study for an additional 6 months (12 months total posttitration) to determine whether the effects of therapy were maintained. RESULTS: During the 6-month extended follow-up period, there were no device malfunctions or device-related serious adverse effects. There were 7 serious adverse effects unrelated to the device, including 3 deaths (2 sudden cardiac deaths, 1 worsening HF death). There were 5 nonserious adverse events that were adjudicated to be device-related. Safety and tolerability were similar, and there were no significant differences in efficacy between left- and right-sided ART. Overall, mean efficacy measure values at 12 months were not significantly different from mean values at 6 months. CONCLUSIONS: Chronic open-loop ART via left- or right-sided VNS continued to be feasible and well-tolerated in patients with HF with reduced EF. Improvements in cardiac function and HF symptoms seen after 6 months of ART were maintained at 12 months.

Autonomic regulation therapy via left or right cervical vagus nerve stimulation in patients with chronic heart failure: results of the ANTHEM-HF trial.

OBJECTIVE: ANTHEM-HF evaluated a novel autonomic regulation therapy (ART) via either left or right vagus nerve stimulation (VNS) in patients with heart failure (HF) and reduced ejection fraction (HFrEF). METHODS AND RESULTS: Sixty subjects (New York Heart Association [NYHA] functional class II-III, left ventricular ejection fraction (LVEF) ≤ 40%, left ventricular end-diastolic diameter ≥ 50 mm to < 80 mm) receiving optimal pharmacologic therapy were randomized at 10 sites. VNS systems were randomly implanted on the left (n = 31) or right (n = 29) side. All patients were successfully implanted and 59 were titrated over 10 weeks to a well tolerated stimulation intensity. One patient died 3 days after an embolic stroke that occurred during implantation. Common device-related adverse events after VNS titration were transient mild dysphonia, cough, and oropharyngeal pain, which were similar for left- and right-side VNS. After 6 months of ART, the adjusted left-right differences in LVEF, left ventricular end-systolic volume (LVESV), and left ventricular end-systolic diameter (LVESD) were 0.2% (95% CI -4.4 to 4.7), 3.7 mL (95% CI -7.0 to 14.4), and 1.3 mm (95% CI -0.9 to 3.6), respectively. In the combined population, absolute LVEF improved by 4.5% (95% CI 2.4-6.6), LVESV improved by -4.1 mL (95% CI -9.0 to 0.8), and LVESD improved by -1.7 mm (95% CI -2.8 to -0.7). Heart rate variability improved by 17 ms (95% CI 6.5-28) with minimal left-right difference. Six-minute walk distance improved an average of 56 m (95% CI 37-75); however, improvement was greater for right-side ART (77 m [95% CI 49-105]). NYHA functional class improved in 77% of patients (baseline to 6 months). CONCLUSIONS: Chronic open-loop ART via left- or right-side VNS is feasible and well tolerated in HFrEF patients. Safety and efficacy measures are encouraging and warrant further study.