Fat infiltration in myocardium in Duchenne muscular dystrophy with atrial tachycardia

A 15-year-old-Japanese boy was admitted to our hospital for the treatment of radiofrequency catheter ablation for atrial flutter and fibrillation. He had been diagnosed with Duchenne muscular dystrophy (DMD) at 3 years old, and he was not able to walk at 8 years. At 12 years, he had heart failure and transthoracic echocardiography (TTE) showed diffuse hypokinesis of left ventricle with an ejection fraction (EF) of 40%. Although treatment for heart failure was started, his condition gradually progressed, and recent medication was as follows; enalapril (7.5 mg/day), torasemide (8 mg/day), eprelenone (50 mg/day), bisoprolol (3.75 mg), and pimobendan (2.5 mg/day) in addition to biphasic positive airway pressure treatment. Recently, he had paroxysmal atrial flutter and fibrillation with heart rate of 180–200/min and electrical shock therapy was performed, repeatedly. On admission, TTE showed EF of 30%. Chest computed tomography showed fat infiltration especially in the left atrium (Panel A, arrows) as well as ventricular walls (Panel B, arrows) and skeletal muscles (Panel C). Unfortunately, catheter ablation was not successful, and apixaban (10 mg/day) was added. DMD is an inherited myopathy that results in progressive skeletal, respiratory, and myocardial weakness. Arrhythmia including atrial tachycardia are more seen in patients with LVEF <35%. Fatty degeneration was also reported as myocardial change in DMD. The present report suggested that fat degeneration may be related to atrial arrhythmia