Abstracts

Rationale: The traditional Vagus Nerve Stimulation (VNS) Therapy® System delivers two stimulation modes: Normal Mode (e.g. scheduled 30s ON and 5 min OFF) and on-demand Magnet Mode (passing magnet over the device). Some patients are unable to utilize the Magnet Mode feature due to their cognitive impairment, seizures during sleep, lack of an aura and/or the disabling effects of the seizure itself. The recently FDA approved AspireSR® VNS Therapy® System with Automatic Stimulation (AutoStim) Mode activates stimulation based on an algorithm that detects rapid relative increases in a heart rate (≥20% from baseline) that may be associated with a seizure. A US investigational study was conducted to obtain data to evaluate the long-term clinical benefits and safety of the AspireSR system.Methods: The E-37 protocol (E-37: IDE G120212; NCT01846741) is a prospective, unblinded, US multi-site study of the AspireSR® in subjects with medically refractory partial onset seizures and history of ictal tachycardia. All traditional VNS Therapy Modes along with the investigational AutoStim Mode were active during long term follow-up. Subjects were assessed for seizure severity, duration, post-ictal duration, and quality of life by using a validated physician questionnaire (NHS3; National Hospital Seizure Severity Scale) and patient reported questionnaires (SSQ; Seizure Severity Questionnaire; QOLIE-31-P: Quality of Life In Epilepsy). Adverse events were also collected.Results: Twenty subjects (ages 21-69) were implanted with the AspireSR VNS Therapy System. At 12 months, all QOLIE-31-P scores exceeded the Minimal Important Change (MIC) criteria for clinical significance and all SSQ improvement scores exceeded twice the MIC criteria. NHS3 also showed a significant improvement from baseline in severity for complex partial seizures at 3, 6 and 12 month follow-up visits. The responder rate (≥ 50% seizure count reduction) increased over time from 20% (4/20) at 3 months, to 35% (7/20) at 6 months, and 50% (10/20) at 12 months.Most commonly reported anticipated adverse events were dysphonia or voice alteration (35%: n=7) and convulsion (30%; n=6) followed by oropharyngeal pain (15%; n= 3).Conclusions: E-37 twelve month data analysis results demonstrate significant clinical benefits of using the traditional VNS Therapy modes in combination with the new AutoStim feature, although the contribution of each feature individually cannot be specified. Reduction in seizure frequency reduced seizure severity and improved post-ictal recovery and quality of life were reported. Additional long-term data analysis will be available at the time of AES conference.