Diffuse Active Myocarditis in a Teenager with Duchenne Muscular Dystrophy - a case report

Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder caused by mutations in the dystrophin gene. These mutations result in the absence or reduced levels of dystrophin protein, leading to progressive skeletal and cardiac muscle deterioration. Cardiomyopathy is almost universally present in patients with DMD who survive into their third decade of life. The clinical onset of cardiac dysfunction is often asymptomatic and typically identified during routine evaluations. Acute deterioration of cardiac function in DMD patients is rarely reported in the medical literature.

We report the case of a 13-year-old boy with DMD and preserved left ventricular (LV) function who presented with severe retrosternal chest pain and electrocardiographic (ECG) abnormalities. Laboratory testing revealed significantly elevated troponin levels, though coronary CT angiography (CTA) was normal. Cardiac magnetic resonance imaging (CMR) confirmed diffuse active myocarditis, demonstrating inflammation and fibrosis involving both the septal and lateral walls-a pattern of fibrosis atypical for Duchenne cardiomyopathy.

Diffuse active myocardial injury with the pattern of active myocarditis is one of the causes of rapid deterioration of LV dysfunction in Duchenne cardiomyopathy and can be detected by CMR.