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. What is Known: • Differential diagnosis in paediatric patients presenting with severe dysfunction is challenging • EMB remains the gold standard technique for the diagnosis of myocarditis and can help to guide treatment What is New: • EMB guided treatment my benefit paediatric patients with inflammatory cardiomyopathy. • Factors associated with a favourable response to treatment in patients presenting with severe cardiac dysfunction include: intense inflammatory infiltrate in EMB, oedema, necrosis, positive viral PCR in the myocardium, high elevation of troponins and negative genetic testing. • Positive genetic testing was observed in some patients with inflammatory cardiomyopathy. In our opinion, genetic testing should be considered in all patients presenting with severe dysfunction. • Interferon β combined with corticosteroids may offer a beneficial treatment approach in patients with Parvovirus B19-induced myocarditis.