Vagus Nerve Stimulation for the Treatment of Heart Failure: The INOVATE-HF Trial.

BACKGROUND: Heart failure (HF) is increasing in prevalence and is a major cause of morbidity and mortality despite advances in medical and device therapy. Autonomic imbalance, with excess sympathetic activation and decreased vagal tone, is an integral component of the pathophysiology of HF. OBJECTIVES: The INOVATE-HF (Increase of Vagal Tone in Heart Failure) trial assessed the safety and efficacy of vagal nerve stimulation (VNS) among patients with HF and a reduced ejection fraction. METHODS: INOVATE-HF was a multinational, randomized trial involving 85 centers including patients with chronic HF, New York Heart Association functional class III symptoms and ejection fraction ≤40%. Patients were assigned to device implantation to provide VNS (active) or continued medical therapy (control) in a 3:2 ratio. The primary efficacy endpoint was composite of death from any cause or first event for worsening HF. RESULTS: Patients (n = 707) were randomized and followed up for a mean of 16 months. The primary efficacy outcome occurred in 132 of 436 patients in the VNS group, compared to 70 of 271 in the control group (30.3% vs. 25.8%; hazard ratio: 1.14; 95% confidence interval: 0.86 to 1.53; p = 0.37). During the trial, the estimated annual mortality rates were 9.3% and 7.1%, respectively (p = 0.19). Quality of life, New York Heart Association functional class, and 6-min walking distance were favorably affected by VNS (p < 0.05), but left ventricular end-systolic volume index was not different (p = 0.49). CONCLUSIONS: VNS does not reduce the rate of death or HF events in chronic HF patients. (INcrease Of VAgal TonE in CHF [INOVATE-HF]; NCT01303718).

Sensing performance of a new wireless implantable loop recorder: a 12-month follow up study.

BACKGROUND: The implantable loop recorder (ILR) is a cost-effective tool with a high diagnostic yield in the evaluation of unexplained recurrent syncope. The Sleuth ILR (Transoma Medical, St. Paul MN, USA) is a new-generation ILR with wireless transmission capability approved by the Food and Drug Administration. We report the feasibility of achieving appropriate sensing over 1-year follow-up at the traditional midclavicular and alternative inframammary implantation sites without preimplant electrocardiogram (ECG) mapping. METHODS AND RESULTS: We studied 32 patients with unexplained syncope, aged 58.4+/-18.44 years, with an ILR implanted at the left midclavicular location (n = 17) or the left inframammary site (n = 15) over 1-year post implant. No preimplant electrocardiogram (ECG) mapping was performed. The highest R-wave amplitudes were observed at the inframammary site, but over the entire follow-up period, amplitudes were not significantly different from those at the midclavicular site. At both sites, R-wave amplitudes at the 6-month follow-up were significantly higher than those measured at 1 week. P-waves were visible in 80-90% of the patients. There was no discernible difference in P-waves (amplitude) relative to implant location. Body mass index, left ventricular ejection fraction, and age did not significantly influence the R-wave amplitude or the ability to discern P-waves. CONCLUSION: Our findings show that the Sleuth ILR implanted at both the midclavicular and inframammary locations without preimplant ECG mapping achieves acceptable "R" waves. This may simplify implantation procedures and improve patient satisfaction.

Adaptive cardiac resynchronization therapy device based on spiking neurons architecture and reinforcement learning scheme.

Spiking neural network (NN) architecture that uses Hebbian learning and reinforcement-learning schemes for adapting the synaptic weights is implemented in silicon and performs dynamic optimization according to hemodynamic sensor for a cardiac resynchronization therapy (CRT) device. The spiking NN architecture dynamically changes the atrioventricular (AV) delay and interventricular (VV) interval parameters according to the information provided by the intracardiac electrograms (IEGMs) and hemodynamic sensors. The spiking NN coprocessor performs the adaptive part and is controlled by a deterministic algorithm master controller. The simulated cardiac output obtained with the adaptive CRT device is 30% higher than with a nonadaptive CRT device and is likely to provide improvement in the quality of life for patients with congestive heart failure. The spiking NN architecture shows synaptic plasticity acquired during the learning process. The synaptic plasticity is manifested by a dynamic learning rate parameter that correlates patterns of hemodynamic sensor with the system outputs, i.e., the optimal AV and VV pacing intervals.

Multi-center clinical experience with a lumenless, catheter-delivered, bipolar, permanent pacemaker lead: implant safety and electrical performance.

PURPOSE: Reduced lead diameter and reliability can be designed into transvenous permanent pacing leads through use of redundant insulation and removal of the stylet lumen. The model 3830 lead (Medtronic Inc., Minneapolis, MN, USA) is a bipolar, fixed-screw, steroid-eluting, lumenless, 4.1-Fr pacing lead. Implantation can be performed in a variety of right heart sites using a deflectable catheter (Model 10600, Medtronic). Lead performance and safety were studied. METHODS: Two prospective trials of 338 implanted subjects from 56 global sites were conducted. Electrical and safety data were obtained at implant, pre-discharge, and up to 18 months post-implant. Leads were implanted at traditional and alternate right heart sites. RESULTS: The study enrolled 338 subjects (204 males, 70.6 +/- 11.6 years) followed-up for a mean of 10.2 months (range, 0-21.6). Mean P-wave amplitudes ranged from 3.2 mV at 3 months to 2.9 mV at 18 months, while mean atrial pulse width thresholds at 2.5 V ranged from 0.07 ms at 3 months to 0.09 ms at 18 months. Mean R-wave amplitudes ranged from 11.3 mV to 11.1 mV and mean ventricular pulse width thresholds at 2.5 V ranged from 0.10 ms to 0.14 ms. There were 22 ventricular and 12 atrial lead complications within 3 months post-implant. Survival from lead-related complications improved to a clinically acceptable rate in the cohort of patients when revised implant techniques were employed. CONCLUSIONS: With the use of recommended implant techniques, the study results support the electrical efficacy and safety of a catheter-delivered, lumenless lead in traditional or alternate right atrium or right ventricle sites through 18 months post-implant.