Facioscapulohumeral muscular dystrophy with sinus dysfunction

We report a 47-year-old man with facioscapulohumeral muscular dystrophy (FSHD) presenting with sinus dysfunction. He became unable to roll over and stand up at the age of 42, but he could still walk. Facial muscle involvement, scapular winging, asymmetrical involvement, funnel chest, and the absence of contractures were typical of FSHD. Electrocardiogram (ECG) and cardiac echogram showed the overload of both right atrium and ventricle. On Holter ECG, transient P wave inversion and P-P interval elongation (maximally 2.4 seconds) repeatedly appeared mainly during sleep. There was no bundle branch block, atrioventricular junctional rhythm, or increase of premature ventricular beats. Vital capacity was decreased (0.62L. 16% of the predicted value). Arterial blood gas analysis showed hypercapnia and hypoxia which aggravated during sleep (PaCO₂ 87.3 Torr, PaO₂ 41.5 Torr). Sleep apnea was not observed. Intracardiac ECG was not performed and he died 2 weeks later. In FSHD, sinus node dysfunction may become distinct especially in the setting of respiratory failure.