Elamipretide (Forzinity™) is a mitochondrial cardiolipin binder being developed by Stealth BioTherapeutics for the treatment of a range of disorders featuring mitochondrial dysfunction. In September 2025, elamipretide was granted accelerated approval in the USA for use to improve muscle strength in adult and pediatric patients with Barth syndrome weighing ≥ 30 kg. With this accelerated approval, elamipretide became the first disease-specific treatment approved for Barth syndrome, an ultra-rare X-linked recessive genetic disorder. Elamipretide is also under phase III clinical development for use in the treatment of dry age-related macular degeneration and mitochondrial myopathies. This article summarizes the milestones in the development of elamipretide leading to this first approval for Barth syndrome.