New-onset heart failure in infants: when the aetiological diagnosis becomes a challenge.

• Both EMB and CMR may show inflammation in infants with new-onset heart failure of any aetiology. • A global approach should be used when facing this diagnostic challenge, including the EMB (number of T-lymphocytes and oedema), some CMR criteria, specially LGE and mappings, the detection of viral agents in cardiac tissue and troponins. Genetic tests should also be performed when studying these patients.