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).

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.

Medication adherence and activity patterns underlying uncontrolled hypertension: Assessment and recommendations by practicing pharmacists using digital health care.

OBJECTIVES: This report summarizes the first use of a digital health feedback system (DHFS) by practicing pharmacists to establish evidence-based blood pressure (BP) management recommendations. SETTING: Fifteen commercial pharmacies and 39 patients in the Isle of Wight participated. PRACTICE DESCRIPTION: The pharmacists were experienced in providing New Medicine Services to patients in their communities. PRACTICE INNOVATION: The pharmacists utilized a commercially available DHFS. The DHFS utilized FDA-cleared and CE-marked class 2 medical devices passively captured and shared information about medication-taking using an ingestible sensor, and daily patterns of rest, activity, and exercise using a wearable patch that incorporates an accelerometer. INTERVENTIONS: Pharmacists provided targeted counselling for BP management as guided by the digital information. EVALUATION: Blood pressure was measured serially, and patient and provider experiences with DHFS use were assessed using satisfaction surveys. RESULTS: The mean change in SBP over the 2-week evaluation period was -7.9 ± 22.1; mean change in DBP was -2.8 ± 12.9. A root cause for persistent hypertension was determined for all of these 34 patients: 68% had pharmaceutical resistance, and 32% had inadequate medication use. Specifically, 29% were found to be capable to achieving blood pressure control on their currently prescribed medications, 68% were found to have a need for additional pharmacological treatment, and 3% needed additional adherence support. Pharmacists found that the DHFD helped in targeting specific recommendations, and to create a collaborative experience with their patients. Patients found the experience to be positive and helpful. CONCLUSION: DHFS that provides confirmation of medication taking and objective measures of lifestyle patterns can help pharmacists to identify specific factors contributing to uncontrolled hypertension, to make evidence-based prescribing and lifestyle recommendations for achieving treatment goals, and to create a collaborative experience for patients in the management of their self-care.

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.

Autonomic regulation therapy for the improvement of left ventricular function and heart failure symptoms: the ANTHEM-HF study.

BACKGROUND: Outcomes of heart failure (HF) have improved dramatically with the use of blockers of the sympathetic and renin-angiotensin-aldosterone systems, as well as with more prevalent use of implantable cardiac defibrillators and cardiac resynchronization therapy. Despite these interventions, however, the overall prognosis of HF patients remains poor. Recently, stimulation of the right cervical vagus nerve in patients with symptomatic heart failure has been evaluated. Results suggest that vagal nerve stimulation provides sustained improvement in left ventricular (LV) function and symptoms associated with HF. However, much remains to be learned about the risks and benefits of therapies that alter autonomic regulatory function for the treatment of heart failure. METHODS: The Autonomic Neural Regulation Therapy to Enhance Myocardial Function in Heart Failure (ANTHEM-HF) study has been designed to address several key clinical questions about the role of autonomic regulation therapy (ART) in patients with LV dysfunction and chronic symptomatic heart failure. CONCLUSIONS: ANTHEM-HF should provide additional and valuable information regarding the safety and the relationship between the site and intensity of ART and its salutary effects on HF.

Autonomic regulation therapy in chronic heart failure with preserved/mildly reduced ejection fraction: ANTHEM-HFpEF study results.

BACKGROUND: Autonomic regulation therapy (ART) utilizing cervical vagus nerve stimulation (VNS) appeared to be safe and to improve autonomic tone, symptoms, and cardiac mechanical function in patients with symptomatic heart failure and reduced ejection fraction in the ANTHEM-HF Study. The ANTHEM-HFpEF Study is the first investigation to evaluate the safety and feasibility of ART in patients with symptomatic heart failure and preserved or mildly reduced ejection fraction (HFpEF, HFmrEF). METHODS: This open-label interventional study enrolled 52 patients with HFpEF or HFmrEF, NYHA Class II-III, and LVEF ≥40%, who received stable guideline-directed medical therapy. All patients were successfully implanted with LivaNova VNS Therapy® system with an electrical lead surrounding the right cervical vagus nerve. RESULTS: Adverse event incidence was low. At 12 months, NYHA class (p <0.0001), 6-min walk distance (p <0.05), and quality of life (p <0.0001) were improved. Cardiac mechanical function measures were normal at baseline, except for left ventricular mass index in women and E/e' ratio in all patients, which were elevated at baseline, and were unchanged by ART. Autonomic tone and reflexes improved, indicated by 29% decrease in low-frequency/high-frequency heart rate variability to normal levels (p = 0.028) and by increased heart rate turbulence slope (p = 0.047). T-wave alternans (p = 0.001) and T-wave heterogeneity (p = 0.001) were reduced from abnormal to normal ranges. Nonsustained ventricular tachycardia incidence decreased (p = 0.027). CONCLUSIONS: ART appeared well-tolerated and safe in patients with HFpEF or HFmrEF. Chronic ART did not alter mechanical function measures but was associated with improved heart failure symptoms, exercise tolerance, autonomic tone, and cardiac electrical stability. CLINICAL TRIAL REGISTRY: Autonomic Neural Regulation Therapy to Enhance Myocardial Function in Heart Failure with Preserved Ejection Fraction [ClinicalTrials.gov #NCT03163030, registered 05/22/2017].

Implantable vagus nerve stimulation system performance is not affected by internal or external defibrillation shocks.

PURPOSE: Autonomic regulation therapy (ART) for heart failure (HF) is delivered using vagus nerve stimulation (VNS), and has been associated with improvement in cardiac function and HF symptoms. VNS is delivered using an implantable pulse generator (IPG) and a lead placed around the cervical vagus nerve. Because HF patients may receive concomitant cardiac defibrillation therapy, testing was conducted to determine the effect of defibrillation (DF) on VNS system performance. METHODS: Normal swine (n = 4) with VNS system implants on the right cervical vagus nerve received sequential defibrillation shocks with three defibrillation systems: an implantable cardioverter defibrillator (ICD), a subcutaneous ICD (S-ICD), and an external cardioverter defibrillator (ECD). Each system delivered a series of bipolar high-energy shocks and reverse-polarity high-energy shocks. RESULTS: The specified cardiac defibrillation shocks were delivered successfully from each of the three defibrillation systems to all animals. After each shock series, interrogation of the IPG confirmed that software and data were unchanged from pre-programmed values. After all of the defibrillation shocks were delivered, the IPGs underwent and passed comprehensive electrical testing demonstrating proper system function. No shifts in IPG parameters or ART system failures were observed, and histologic evaluation of the vagus nerve revealed no anatomic changes. CONCLUSIONS: Implantable VNS systems were tested in vivo for immunity to defibrillation via ICD, S-ICD, and ECD, and were found to be unaffected by a series of high-energy defibrillation shocks. These results confirm that ART systems are capable of continuing to function after defibrillation and the cervical vagus nerve is anatomically unaffected.

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].

Advances in Our Clinical Understanding of Autonomic Regulation Therapy Using Vagal Nerve Stimulation in Patients Living With Heart Failure.

The ANTHEM-HF, INOVATE-HF, and NECTAR-HF clinical studies of autonomic regulation therapy (ART) using vagus nerve stimulation (VNS) systems have collectively provided dose-ranging information enabling the development of several working hypotheses on how stimulation frequency can be utilized during VNS for tolerability and improving cardiovascular outcomes in patients living with heart failure (HF) and reduced ejection fraction (HFrEF). Changes in heart rate dynamics, comprising reduced heart rate (HR) and increased HR variability, are a biomarker of autonomic nerve system engagement and cardiac control, and appear to be sensitive to VNS that is delivered using a stimulation frequency that is similar to the natural operating frequency of the vagus nerve. Among prior studies, the ANTHEM-HF Pilot Study has provided the clearest evidence of autonomic engagement with VNS that was delivered using a stimulation frequency that was within the operating range of the vagus nerve. Achieving autonomic engagement was accompanied by improvement from baseline in six-minute walk duration (6MWD), health-related quality of life, and left ventricular EF (LVEF), over and above those achieved by concomitant guideline-directed medical therapy (GDMT) administered to counteract harmful neurohormonal activation, with relative freedom from deleterious effects. Autonomic engagement and positive directional changes have persisted over time, and an exploratory analysis suggests that improvement in autonomic tone, symptoms, and physical capacity may be independent of baseline NT-proBNP values. Based upon these encouraging observations, prospective, randomized controlled trials examining the effects on symptoms and cardiac function as well as natural history have been warranted. A multi-national, large-scale, randomized, controlled trial is well underway to determine the outcomes associated with ART using autonomic nervous system engagement as a guide for VNS delivery.

Effect of defibrillation on the performance of an implantable vagus nerve stimulation system.

BACKGROUND: Vagus Nerve Stimulation (VNS) delivers Autonomic Regulation Therapy (ART) for heart failure (HF), and has been associated with improvement in cardiac function and heart failure symptoms. VNS is delivered using an implantable pulse generator (IPG) and lead with electrodes placed around the cervical vagus nerve. Because HF patients may receive concomitant cardiac defibrillation therapy, testing was conducted to determine the effect of defibrillation (DF) on the VNS system. METHODS: DF testing was conducted on three ART IPGs (LivaNova USA, Inc.) according to international standard ISO14708-1, which evaluated whether DF had any permanent effects on the system. Each IPG was connected to a defibrillation pulse generator and subjected to a series of high-energy pulses. RESULTS: The specified series of pulses were successfully delivered to each of the three devices. All three IPGs passed factory electrical tests, and interrogation confirmed that software and data were unchanged from the pre-programmed values. No shifts in parameters or failures were observed. CONCLUSIONS: Implantable VNS systems were tested for immunity to defibrillation, and were found to be unaffected by a series of high-energy defibrillation pulses. These results suggest that this VNS system can be used safely and continue to function after patients have been defibrillated.

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.

Comparison of symptomatic and functional responses to vagus nerve stimulation in ANTHEM-HF, INOVATE-HF, and NECTAR-HF.

AIMS: Clinical studies of vagal nerve stimulation (VNS) for heart failure with reduced ejection fraction have had mixed results to date. We sought to compare VNS delivery and associated changes in symptoms and function in autonomic regulation therapy via left or right cervical vagus nerve stimulation in patients with chronic heart failure (ANTHEM-HF), increase of vagal tone in heart failure (INOVATE-HF), and neural cardiac therapy for heart failure (NECTAR-HF) for hypothesis generation. METHODS AND RESULTS: Descriptive statistics were used to analyse data from the public domain for differences in proportions using Pearson's chi-square test, differences in mean values using Student's unpaired t-test, and differences in changes of mean values using two-sample t-tests. Guideline-directed medical therapy recommendations were similar across studies. Fewer patients were in New York Heart Association 3, and baseline heart rate (HR) was higher in ANTHEM-HF. In INOVATE-HF, VNS was aimed at peripheral neural targets, using closed-loop delivery that required synchronization of VNS to R-wave sensing by an intracardiac lead. Pulse frequency was low (1-2 Hz) because of a timing schedule allowing ≤3 pulses of VNS following at most 25% of detected R waves. NECTAR-HF and ANTHEM-HF used open-loop VNS delivery (i.e. independent of any external signal) aimed at both central and peripheral targets. In NECTAR-HF, VNS delivery at 20 Hz caused off-target effects that limited VNS up-titration in a majority of patients. In ANTHEM-HF, VNS delivery at 10 Hz allowed up-titration until changes in HR dynamics were confirmed. Six months after VNS titration, significant improvements in both HR and HR variability occurred only in ANTHEM-HF. When ANTHEM-HF and NECTAR-HF were compared, greater improvements from baseline were observed in ANTHEM-HF in standard deviation in normal-to-normal R-R intervals (94 ± 26 to 111 ± 50 vs. 146 ± 48 to 130 ± 52 ms; P < 0.001), left ventricular ejection fraction (32 ± 7 to 37 ± 0.4 vs. 31 ± 6 to 33 ± 6; P < 0.05), and Minnesota Living with Heart Failure mean score (40 ± 14 to 21 ± 10 vs. 44 ± 22 to 36 ± 21; P < 0.002). When compared with INOVATE-HF, greater improvement in 6-min walk distance was observed in ANTHEM-HF (287 ± 66 to 346 ± 78 vs. 304 ± 111 to 334 ± 111 m; P < 0.04). CONCLUSIONS: In this post-hoc analysis, differences in patient demographics were seen and may have caused the differential responses in symptoms and function observed in association with VNS. Major differences in technology platforms, neural targets, VNS delivery, and HR and HR variability responses could have also potentially played a very important role. Further study is underway in a randomized controlled trial with these considerations in mind.

Serum potassium and clinical outcomes in the Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study (EPHESUS).

BACKGROUND: Aldosterone blockade is recommended for patients with congestive heart failure after acute myocardial infarction complicated by left ventricular systolic dysfunction; however, the perceived risk of hyperkalemia may limit implementation of this therapeutic approach. This subanalysis examined the relationship between eplerenone, serum potassium (K(+)), and clinical outcomes in the Eplerenone Post-Acute Myocardial Infarction Heart Failure Efficacy and Survival Study (EPHESUS). METHODS AND RESULTS: Hospitalized patients with congestive heart failure after acute myocardial infarction complicated by left ventricular systolic dysfunction (left ventricular ejection fraction < or =40%) treated with standard therapy were randomized 3 to 14 days after the acute myocardial infarction to additional treatment with eplerenone (25 to 50 mg/d; n=3319) or placebo (n=3313). Patients were excluded if baseline K(+) was >5.0 mEq/L or serum creatinine was >2.5 mg/dL. In patients receiving standard therapy, the addition of eplerenone resulted in a 4.4% absolute increase in the incidence of K(+) >5.5 mEq/L, a 1.6% increase of K(+) > or =6.0 mEq/L, and a 4.7% absolute decrease in hypokalemia (K(+) <3.5 mEq/L). Four independent baseline predictors of hyperkalemia (defined as > or =6.0 mEq/L) were identified: potassium (K(+) greater than the median; 4.3 mEq/L), estimated glomerular filtration rate (< or =60 mL . min(-1) . 1.73 m(-2)), history of diabetes mellitus, and prior use of antiarrhythmic agents. None of these independent baseline risk factors significantly impacted the cardiovascular benefit of eplerenone for reducing all-cause mortality. CONCLUSIONS: Use of selective aldosterone blockade with eplerenone within the dose range of 25 to 50 mg/d in post-acute myocardial infarction patients with heart failure and left ventricular systolic dysfunction who are treated with standard therapy improves outcomes without an excess of risk of hyperkalemia (> or =6.0 mEq/L) when periodic monitoring of serum K(+) is instituted.

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.

Impact of Autonomic Regulation Therapy in Patients with Heart Failure: ANTHEM-HFrEF Pivotal Study Design.

BACKGROUND: The ANTHEM-HFrEF (Autonomic Regulation Therapy to Enhance Myocardial Function and Reduce Progression of Heart Failure with Reduced Ejection Fraction) pivotal study is an adaptive, open-label, randomized, controlled study evaluating whether autonomic regulation therapy will benefit patients with advanced HFrEF. While early-phase studies have supported potential use of vagus nerve stimulation to deliver autonomic regulation therapy for HFrEF, results of larger clinical trials have been inconsistent. The ANTHEM-HFrEF study uses a novel design, with adaptive sample size selection, evaluating effects on morbidity and mortality as well as symptoms and function. METHODS: The ANTHEM-HFrEF study will randomize patients (2:1) to autonomic regulation therapy plus guideline-directed medical therapy, or guideline-directed medical therapy alone. The morbidity and mortality trial utilizes a conventional frequentist approach for analysis of the primary outcome end point-reduction in the composite of cardiovascular death or first HF hospitalization-and a Bayesian adaptive approach toward sample size selection. Embedded within the ANTHEM-HFrEF study is a second trial evaluating improvement in symptoms and function. Symptom/function success will require meeting 2 risk-related conditions (trend for reduced cardiovascular death/HF hospitalization and sufficient freedom from device-related serious adverse events) and 3 efficacy end point components (changes in left ventricular EF, 6-minute walk distance, and Kansas City Cardiomyopathy Questionnaire overall score). CONCLUSIONS: Vagus nerve stimulation remains a promising, yet unproven treatment in HFrEF. A successful ANTHEM-HFrEF pivotal study would provide an important advance in HFrEF treatment and offer a model for expediting evaluation of new therapies. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT03425422.

Autonomic regulation therapy to enhance myocardial function in heart failure patients: the ANTHEM-HFpEF study.

BACKGROUND: Approximately half of the patients presenting with new-onset heart failure (HF) have HF with preserved left ventricular ejection fraction (HFpEF) and HF with mid-range left ventricular ejection fraction (HFmrEF). These patients have neurohormonal activation like that of HF with reduced ejection fraction; however, beta-blockers and angiotensin-converting enzyme inhibitors have not been shown to improve their outcomes, and current treatment for these patients is symptom based and empiric. Sympathoinhibition using parasympathetic stimulation has been shown to improve central and peripheral aspects of the cardiac nervous system, reflex control, induce myocyte cardioprotection, and can lead to regression of left ventricular hypertrophy. Beneficial effects of autonomic regulation therapy (ART) using vagus nerve stimulation (VNS) have also been observed in several animal models of HFpEF, suggesting a potential role for ART in patients with this disease. METHODS: The Autonomic Neural Regulation Therapy to Enhance Myocardial Function in Patients with Heart Failure and Preserved Ejection Fraction (ANTHEM-HFpEF) study is designed to evaluate the feasibility, tolerability, and safety of ART using right cervical VNS in patients with chronic, stable HFpEF and HFmrEF. Patients with symptomatic HF and HFpEF or HFmrEF fulfilling the enrolment criteria will receive chronic ART with a subcutaneous VNS system attached to the right cervical vagus nerve. Safety parameters will be continuously monitored, and cardiac function and HF symptoms will be assessed every 3 months during a post-titration follow-up period of at least 12 months. CONCLUSIONS: The ANTHEM-HFpEF study is likely to provide valuable information intended to expand our understanding of the potential role of ART in patients with chronic symptomatic HFpEF and HFmrEF.

Predictors of sudden cardiac death and appropriate shock in the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) Trial.

BACKGROUND: The factors that determine the risk for sudden death or implantable cardioverter defibrillator therapy in patients receiving cardiac resynchronization therapy (CRT) therapies are largely unknown. METHODS AND RESULTS: We hypothesized that clinical measures of heart failure severity and the presence of comorbid conditions would predict the risk of malignant arrhythmias in the 1520 patients enrolled in the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) Trial. Outcomes in the CRT group after implantable cardioverter defibrillator therapy were also evaluated. The CRT-defibrillator device reduced the risk of sudden death by 56% compared with drug therapy (17 of 595 [2.9%] versus 18 of 308 [5.8%], P<0.02). CRT therapy was not associated with sudden death risk reduction (48 of 617 [7.8%]). Other factors associated with reduced sudden death risk were left ventricular ejection fraction >20% (HR, 0.55 [95% CI, 0.35 to 0.87]; P=0.01), QRS duration >160 ms (HR, 0.63 [95% CI, 0.40 to 0.997]; P=0.05), and female gender (HR, 0.56 [95% CI, 0.34 to 0.94]; P=0.003). The risk for sudden death was increased by advanced New York Heart Association class IV heart failure (HR, 2.62 [95% CI, 1.61 to 4.26]; P<0.011) and renal dysfunction (HR, 1.69 [95% CI, 1.06 to 2.69]; P=0.03). An appropriate shock was experienced in 88 (15%) of the 595 CTR-D patients. In the CRT-defibrillator patients, female gender (HR, 0.54 [95 % CI, 0.31 to 0.94]; P=0.03) and use of neurohormonal antagonists were associated with reduced risk. Class IV heart failure status increased risk. Appropriate implantable cardioverter defibrillator therapy was positively associated with risk of death or all-cause hospitalization (HR, 1.57; P<0.002), pump failure death or hospitalization (HR, 2.35; P<0.001), and sudden death (HR, 2.99; P=0.03), but not total mortality (HR, 1.3; P=0.28). CONCLUSIONS: In CRT candidates, sudden cardiac death risk is associated with higher New York Heart Association class and renal dysfunction. In CRT-defibrillator recipients, reduction in the risk of an appropriate shock is associated with medical therapy with neurohormonal antagonists, female gender, and New York Heart Association functional class III versus IV clinical status. Shock therapy was associated with worse outcome.

Cardiac-resynchronization therapy with or without an implantable defibrillator in advanced chronic heart failure.

BACKGROUND: We tested the hypothesis that prophylactic cardiac-resynchronization therapy in the form of biventricular stimulation with a pacemaker with or without a defibrillator would reduce the risk of death and hospitalization among patients with advanced chronic heart failure and intraventricular conduction delays. METHODS: A total of 1520 patients who had advanced heart failure (New York Heart Association class III or IV) due to ischemic or nonischemic cardiomyopathies and a QRS interval of at least 120 msec were randomly assigned in a 1:2:2 ratio to receive optimal pharmacologic therapy (diuretics, angiotensin-converting-enzyme inhibitors, beta-blockers, and spironolactone) alone or in combination with cardiac-resynchronization therapy with either a pacemaker or a pacemaker-defibrillator. The primary composite end point was the time to death from or hospitalization for any cause. RESULTS: As compared with optimal pharmacologic therapy alone, cardiac-resynchronization therapy with a pacemaker decreased the risk of the primary end point (hazard ratio, 0.81; P=0.014), as did cardiac-resynchronization therapy with a pacemaker-defibrillator (hazard ratio, 0.80; P=0.01). The risk of the combined end point of death from or hospitalization for heart failure was reduced by 34 percent in the pacemaker group (P<0.002) and by 40 percent in the pacemaker-defibrillator group (P<0.001 for the comparison with the pharmacologic-therapy group). A pacemaker reduced the risk of the secondary end point of death from any cause by 24 percent (P=0.059), and a pacemaker-defibrillator reduced the risk by 36 percent (P=0.003). CONCLUSIONS: In patients with advanced heart failure and a prolonged QRS interval, cardiac-resynchronization therapy decreases the combined risk of death from any cause or first hospitalization and, when combined with an implantable defibrillator, significantly reduces mortality.