Metabolic cardiomyopathies: untangling clinical heterogeneity with human stem-cell derived models.

Inherited metabolic diseases are rare monogenic conditions that disrupt biochemical pathways, affecting energy production and homeostasis, often leading to damaging metabolite accumulation. These disorders are clinically heterogeneous and can impact all organs, including the heart. Metabolic cardiomyopathies present with varying severity and unpredictable prognosis, complicating patient care. Pre-clinical research aims to model these cardiomyopathies to understand their pathophysiological mechanisms and develop personalised treatments. Animal models have provided insights into cardiac pathology and treatment, but species differences limit data translation. Human induced pluripotent stem cells (hiPSC) offer a valuable tool for establishing disease models using reprogrammed somatic cells from patients and healthy donors, differentiated into disease-relevant cell types. Cardiomyocytes generated in significant numbers are crucial for investigating cardiac mechanisms and assessing patient-specific drug responses. This review summarises literature on metabolic cardiomyopathies, focusing on long-chain fatty acid oxidation disorders and Barth syndrome. We highlight cardiac readouts from various models and discuss the potential of hiPSC technologies as clinically relevant disease models.