Mechanisms for Arrhythmias in Duchenne Cardiomyopathy
The substrate for arrhythmias in DMD remains under investigation.
Progressive myocardial fibrosis may produce scar which disrupts normal
myocardial electrical coordination. Fibrosis manifests as late
gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR)
imaging, most often involving the posterobasal subepicardial muscle.
Advanced disease features LGE expanding to the inferior and lateral
wall, with increasing thickness of affected
myocardium5,6. Electrocardiogram (ECG) abnormalities
in DMD were described greater than 50 years ago and in general are
thought to mirror the pattern of myocardial injury7.
Altered electrical activation (depolarization) results in changes to the
QRS complex voltage and are commonly identified8,9.
Fragmented QRS complexes in adults represent heterogeneous myocardial
activation in both ischemic and non-ischemic cardiomyopathy have been
associated with arrhythmic events and sudden cardiac
death10. Specifically in the DMD population, QRS
fragmentation is associated with both left ventricular systolic
dysfunction and ventricular ectopy burden11.