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

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.

Vagal stimulation in heart failure

Vagal nerve stimulation (VNS) has a strong pathophysiological rationale as a potentially beneficial treatment for heart failure with reduced ejection fraction. Despite several promising preclinical studies and pilot clinical studies, the two large, controlled trials—NECTAR-HF and INOVATE-HF—failed to demonstrate the expected benefit. It is likely that clinical application of VNS in phase III studies was performed before a sufficient degree of understanding of the complex pathophysiology of autonomic electrical modulation had been achieved, therefore leading to an underestimation of its potential benefit. More knowledge on the complex dose–response issue of VNS (i.e., pulse amplitude, frequency, duration and duty cycle) has been gathered since these trials and a new randomized study is currently underway with an adaptive design and a refined approach in an attempt to deliver the proper dose to a more selected group of patients.

Vagus Nerve Stimulation in Early Stage of Acute Myocardial Infarction Prevent Ventricular Arrhythmias and Cardiac Remodeling

Aims: To evaluate whether low level left vagus nerve stimulation (LLVNS) in early stage of myocardial infarction (MI) could effectively prevent ventricular arrhythmias (VAs) and protect cardiac function, and explore the underlying mechanisms.

Methods and Results: After undergoing implantable cardioverter defibrillators (ICD) and left cervical vagal stimulators implantation and MI creation, 16 dogs were randomly divided into three groups: the MI (n = 6), MI+LLVNS (n = 5), and sham operation (n = 5) groups. LLVNS was performed for 3 weeks. VAs, the left ventricular function, the density of the nerve fibers in the infarction area and gene expression profiles were analyzed. Compared with the MI group, dogs in the MI+LLVNS group had a lower VAs incidence (p < 0.05) and better left ventricular function. LLVNS significantly inhibited excessive sympathetic nerve sprouting with the evidences of decreased density of TH, GAP43 and NF positive nerves (p < 0.05). The gene expression profiling found a total of 206 genes differentially expressed between MI+LLVNS and MI dogs, mainly involved in cardiac tissue remodeling, cardiac neural remodeling, immune response and apoptosis. These genes, including 55 up-regulated genes and 151 down-regulated genes, showed more protective expressions under LLVNS.

Conclusions: This study suggests that LLVNS was delivered without altering heart rate, contributing to reduced incidences of VAs and improved left ventricular function. The potential mechanisms included suppressing cardiac neuronal sprouting, inhibiting excessive sympathetic nerve sprouting and subduing pro-inflammatory responses by regulating gene expressions from a canine experimental study.