Abstract

Rare cardiomyopathies (CMPs) may result from infiltrative disorders, such as amyloidosis, as well as from inherited metabolic diseases, where pathophysiological mechanisms vary depending on the specific defect, including impaired energy production, accumulation of toxic metabolites, or substrate storage. Across this spectrum, nutritional factors play a dual and often underappreciated role: they may drive disease mechanisms or modulate prognosis through malnutrition, sarcopenia or cachexia. In several inborn errors of metabolism, such as glycogen storage diseases and organic acidemias, a targeted diet constitutes etiological therapy, preventing life-threatening metabolic crises and stabilizing cardiac function. In others, including systemic amyloidosis and Fabry disease, nutritional disturbances, such as malabsorption, sarcopenia and cachexia, exacerbate organ involvement and worsen survival despite disease-specific treatments. Importantly, treatable nutritional deficiencies may themselves present with CMPs: primary carnitine deficiency can cause dilated cardiomyopathy reversible with supplementation, while riboflavin has shown therapeutic benefit in ACAD9-related mitochondrial cardiomyopathy.

The interaction between nutrition and cardiomyopathy is complex and bidirectional: metabolic blocks, gastrointestinal involvement, and chronic inflammation precipitate malnutrition, while nutritional deterioration independently predicts worse outcomes. Conventional tools, such as body mass index (BMI) and serum albumin, are often inadequate; refined techniques, including bioelectrical impedance analysis, dual-energy X-ray absorptiometry and functional tests, provide a more accurate assessment.

Evidence indicates that malnutrition, cachexia, and sarcopenia are strong prognostic factors, while targeted interventions ranging from cornstarch protocols in glycogen storage disorders to cofactor supplementation in mitochondrial and metabolic CMPs can stabilize patients and improve quality of life.
This review synthesizes disease-specific paradigms, highlights cross-cutting mechanisms, and outlines principles of personalized intervention, with emphasis on the role of multidisciplinary teams. Nutrition should no longer be regarded as supportive care, but as a therapeutic axis central to rare cardiomyopathy management, with direct implications for survival, function, and patient-centered outcomes.