Figure 1: ECG of a patient with dystrophin-deficient cardiomyopathy. Complex QRS morphology and fragmentation reflect abnormal depolarization of myocardium.

The mechanism for arrhythmia in the dystrophin-deficient cardiomyopathy involves not just fibrosis of the myocardial tissue, but derangement of the molecular electrophysiology of conduction system cells themselves. These specialized cells are reliant on dystrophin to support organization of ion channels and promote coordinated electrical activity¹². In mouse models deficient in dystrophin, misregulation of critical ion channels in specialized conduction tissue cells disturbs electrical activity, contributing to the arrhythmogenesis in the dystrophin-deficient heart^13,14. On electrocardiogram, both short and long PR intervals may be observed, and complete heart block has been observed¹⁵.