Accessory-pathway-mediated dilated cardiomyopathy in an infant.

We report the case of a 10-month-old infant presenting with dilated cardiomyopathy caused by septal dyssynchrony linked to a right septal accessory pathway-mediated pre-excitation. No atrioventricular reciprocating tachycardia was reported, but this pre-excitation resulted in left septal dyssynchrony. After the introduction of flecainide therapy, the antegrade pre-excitation disappeared on ECG, leading to normalisation of left ventricular function.