Elamipretide in pediatric Barth syndrome: from heart failure to school return

Barth syndrome (BTHS) is a rare X-linked mitochondrial disorder characterized by cardiomyopathy, neutropenia, and skeletal myopathy. Elamipretide is a mitochondria-targeting peptide that stabilizes cardiolipin and improves mitochondrial function. While use of this treatment in infants with BTHS has been reported in the United States, no cases have been described outside the US or in older children.

We report the first case of a preschool-aged child with genetically confirmed BTHS and advanced heart failure, who was treated with elamipretide under a compassionate use program approved by the French Drug Administration (ANSM). At treatment initiation, this 5-year-old patient presented with severe left ventricular dysfunction (LVEF = 20%) and moderate-to-severe mitral regurgitation. He was dependent on gastrostomy feeding and had been listed for heart transplantation. Subcutaneous elamipretide (10 mg/day) was initiated alongside maximal conventional heart failure therapy. Over six months, LVEF improved to 50%, mitral regurgitation decreased to mild, Ross class improved from IV to I, and substantial gains were observed in functional capacity, nutritional status, and health-related quality of life (HRQoL). The patient returned to full-time school and remained temporarily suspended from the transplant list. Treatment was generally well tolerated. One transient, non-serious episode of abdominal pain with moderate pancreatic enzyme elevation occurred, which resolved without treatment discontinuation.

This case suggests that elamipretide may improve cardiac function, exercise tolerance, nutrition, and HRQoL in preschool-aged pediatric BTHS patients, potentially delaying the need for transplantation. Broader pediatric evaluation is warranted. Further strategies, such as youth-tailored hybrid cardiac rehabilitation programs, could complement pharmacological therapy and further optimize outcomes in this population.