Unusual cause of myocardial infarction in a 3-year-old: role of cardiovascular magnetic resonance in diagnosis-a case report.

BACKGROUND

Myocardial infarction (MI) is an exceptionally rare occurrence in young children, with most cases linked to congenital or inflammatory causes. We describe a 3-year-old girl with an unusual presentation of embolic MI secondary to dilated cardiomyopathy (DCM) and highlight the pivotal role of cardiovascular magnetic resonance (CMR) imaging in achieving an accurate diagnosis. The aim is to emphasize the importance of advanced imaging especially in rare presentations of myocardial injury.

CASE SUMMARY: We present the case of a 3-year-old girl who was admitted with lethargy and breathlessness. Examination revealed tachycardia and a systolic murmur. Investigations showed cardiomegaly on chest X-ray, elevated and rising troponin levels, and echocardiography-indicated DCM with severely impaired left ventricular function and biventricular thrombi. Initially, the diagnosis of myocarditis was considered due to elevated troponin levels. However, the evolving electrocardiographic (ECG) changes prompted further investigation with CMR. Cardiovascular magnetic resonance findings showed no myocardial oedema or inflammation, ruling out active myocarditis. Instead, it revealed a transmural myocardial infarction in the left ventricular apical segments, along with subtle mid-wall fibrosis in the basal and mid-septal areas. Additionally, severely dilated left and right ventricular volumes and significantly reduced ejection fractions were observed. These findings were consistent with an embolic MI affecting the distal left anterior descending (LAD) artery territory, most likely originating from the biventricular thrombi, in the context of severe DCM.

DISCUSSION: This case underscores the diagnostic complexity of myocardial injury in children and the indispensable role of CMR in distinguishing between aetiologies such as myocarditis and MI.