Replacement of Traditional Vagus Nerve Stimulation with Cardiac-Based Device and Seizure Reduction: A Systematic Review and Meta-Analysis

Introduction For patients with drug-resistant epilepsy (DRE) who are not suitable for surgical resection, neuromodulation with vagus nerve stimulation (VNS) is an established approach. However, there is limited evidence of seizure reduction when replacing traditional VNS (tVNS) device with a cardiac-based one (cbVNS). This meta-analysis compares the seizure reduction achieved by replacing tVNS with cbVNS in a population with DRE. Methods We systematically searched PubMed, Embase, and Cochrane Central following PRISMA guidelines. The main outcomes were number of patients experiencing a ≥50% and ≥80% reduction in seizures, as defined by the McHugh scale. Additionally, we assessed the number of patients achieving freedom from seizures. Results We included 178 patients with DRE from 7 studies who were initially treated with tVNS and subsequently had it replaced by cbVNS. The follow-up for cbVNS ranged from 6 to 37.5 months. There was a statistically significant reduction in seizure frequency with the replacement of tVNS by cbVNS, using a ≥50% (OR 1.79; 95% CI 1.07 to 2.97; I²=0%; p=0.03) and a ≥80% (OR 2.06; 95% CI 1.17 to 3.62; I²=0%; p=0.01) reduction threshold. Nineteen (13%) participants achieved freedom from seizures after switching to cbVNS. There was no difference in the rate of freedom from seizures between groups (OR 1.85; 95% CI 0.81 to 4.21; I²=0%; p=0.14). Conclusion In patients with DRE undergoing battery replacement, cbVNS might be associated with seizure reduction (≥50% and ≥80% threshold) after switching from tVNS. Randomised controlled trials are necessary to validate these findings.