Histological guided treatment in paediatric patients presenting with severe left ventricular dysfunction

Differential diagnosis in children presenting with dilated cardiomyopathy and severe cardiac dysfunction is challenging. In our hospital, a protocol was established in 2015 in which endomyocardial biopsy (EMB) was performed in selected patients and treatment was guided by biopsy results. The study aims to describe our experience with this diagnostic and therapeutic strategy. We performed a unicenter paediatric ambispective study that include patients with dilated cardiomyopathy and severe cardiac dysfunction (left ventricular ejection fraction (LVEF) < 35%) in whom EMB was performed and treatment was prescribed based on EMB results from February 2015 to December 2024. 23 patients (24 episodes) were included. 15 patients had a complete recovery, 5 patients had a partial response to treatment and 4 had no response to treatment. Patients were divided into two groups, those with complete recovery (15) and those without complete recovery (9). No differences were observed in sex, age, clinical presentation, need for Extracorporeal Membrane Oxygenation (ECMO) or echocardiogram parameters. Complete recovery was associated with a higher degree of inflammation on EMB (p < 0.001), necrosis (= 0.007) and oedema (p = 0.036), negative genetic testing (p < 0.001), higher troponin values (p = 0.015) and positive viral PCR in myocardial tissue (p < 0.001). Conclusion: EMB is a valuable tool for diagnosis and treatment of paediatric patients presenting with dilated cardiomyopathy. Factors associated with a favourable response to therapy include: intense inflammatory infiltrate in EMB, oedema, necrosis, positive viral PCR found in the myocardium, high elevation of troponins and negative genetic testing.