Long-term Data on the Cardiovascular Safety Profile of Fenfluramine in the Treatment of Dravet Syndrome: Interim Analysis of an Open-label Safety Extension Study

Rationale: In two recently completed Phase 3 clinical trials, fenfluramine has demonstrated superior efficacy compared with placebo for the reduction of convulsive seizures in children and young adults (2–18 years old) with Dravet syndrome. Fenfluramine, previously marketed for weight loss, was withdrawn from the market in 1997 following reports of cardiac valvular heart disease (VHD) and pulmonary hypertension in obese adults treated with ≥ 60 mg/day. Here we report the cardiovascular safety findings from an interim analysis of the long-term safety extension study (NCT02823145) of low-dose fenfluramine for the treatment of Dravet syndrome in children and young adults.