Targeted Dried Blood Spot Acylcarnitine and Amino Acid Profiling Reveals a Candidate Metabolic Signature in Pediatric Heart Failure: A Cross-Sectional Case–Control Study

Abstract Pediatric heart failure (HF) causes substantial morbidity and mortality, yet the metabolic derangements underlying myocardial energy failure in children remain incompletely characterized. We performed targeted dried blood spot (DBS) acylcarnitine and amino acid profiling in 30 children with HF of mixed etiology and 30 age- and sex-frequency-matched healthy controls, quantifying 44 metabolites by flow-injection tandem mass spectrometry. Seven metabolites were significantly decreased in HF patients (p < 0.05, FDR < 0.05): hexanoylcarnitine/adipoylcarnitine (C6DC), tyrosine, octenoylcarnitine (C8:1), glutamate, decadienoylcarnitine (C10:2), proline, and dodecanoylcarnitine (C12), with decreases of 23.9–48.8%. Hydroxyoctadecanoic acid (C18OH) showed the largest overall decrease (57.7%) but did not reach FDR significance. Multivariate modeling using the full metabolite panel achieved excellent, permutation-validated discrimination between groups (PLS-DA accuracy 98%, Q²=0.82; OPLS-DA R²Y = 0.835, Q²=0.708); six metabolites (C6DC, tyrosine, C8:1, glutamate, C10:2, and proline) emerged as the top contributors to this discrimination and are proposed as an exploratory minimal candidate panel, warranting dedicated validation of its own discriminatory performance in larger, independent cohorts. Pathway enrichment highlighted catecholamine biosynthesis, thyroid hormone synthesis, and aromatic amino acid metabolism, without enrichment of fatty-acid β-oxidation or carnitine-synthesis pathways. These findings indicate that pediatric HF involves a coordinated decrease in medium-chain/dicarboxylic acylcarnitines and selected amino acids alongside enrichment of catecholaminergic and aromatic amino-acid pathways, consistent with a myocardial shift away from fatty-acid oxidation. A small, low-cost DBS-based panel may hold promise as a non-invasive adjunct for pediatric HF assessment, pending external validation.