Suspected myocardial infarction in an extremely preterm infant

Neonatal myocardial infarction is rare, lacks standardized treatment strategies, and is associated with a poor prognosis. In preterm infants, neonatal myocardial infarction is primarily attributed to distal coronary microvascular injury and microthrombosis. Diagnosis is often missed because of nonspecific clinical manifestations, and unified clinical guidelines have not yet been established. This report describes an extremely preterm female infant whose initial presenting manifestations were oliguria and anasarca. Key echocardiographic findings in the acute phase included myocardial edema, segmental wall motion abnormalities, pericardial effusion, reduced left ventricular systolic function, and severe mitral regurgitation. Following fluid restriction, diuretic therapy, myocardial protective agents, correction of electrolyte and acid-base disturbances, and respiratory supportive care targeting underlying comorbidities, the patient improved clinically and was discharged. Long-term follow-up revealed acceptable somatic growth with mild neurodevelopmental delay; however, structural cardiac sequelae persisted.