473: Early Versus Late Use of Lacosamide as an Antiseizure Medication in Refractory Status Epilepticus

Introduction: Status epilepticus is initially treated with a benzodiazepine followed by a first-line anti-seizure medication (ASM) such as levetiracetam, valproic acid or fosphenytoin. Despite prompt therapy, up to one-third of patients progress to refractory status epilepticus (RSE). While lacosamide is frequently used in RSE due to its favorable safety profile, its optimal timing and efficacy remain unclear. This study evaluated lacosamide’s effectiveness in seizure cessation based on early (second-line) versus late (third-line or beyond) administration. Methods: This study was a multicentered retrospective review of adult ICU patients with RSE admitted to eight AdventHealth hospitals between July 2022 and March 2024. Patients were excluded if they were allergic to lacosamide or taking it prior to admission. The primary outcome was seizure cessation following lacosamide, defined as the absence of clinical and electrographic seizures without the need for additional ASMs or anesthetic dose escalation. Secondary outcomes included total number of ASMs used, hospital and ICU length of stay, mortality, and adverse effects. Results: Forty-one patients were included, with 25 patients being classified as receiving early lacosamide and 16 patients receiving it later. Baseline characteristics were similar between groups. Initial treatment prior to lacosamide included a median of 2.4 mg lorazepam equivalents in the early group and 3.5 mg lorazepam equivalents in the late group. The most commonly utilized first-line ASM was levetiracetam, with median loading doses of 2,500 mg in the early group and 1,750 mg in the late group. The median loading dose of lacosamide was 200 mg in the early group and 300 mg in the late group. Seizure cessation occurred in 44% (11/25) of early group patients versus 31% (5/16) in the late group (p=0.41). Notably, the early group required significantly fewer total ASMs (p < 0.001). Safety and other secondary endpoints were similar between groups. Conclusions: Early use of lacosamide in RSE was associated with significantly fewer ASMs used and numerically higher rates of seizure cessation, suggesting potential clinical benefit despite lack of statistical significance in the primary outcome. Further studies with larger sample sizes are warranted to validate these results.