Autosomal recessive paediatric sick sinus syndrome associated with novel compound mutations in SCN5A

We report the case of a boy who was first addressed to medical attention when he was 2-years-old because of an episode of Salmonellosis. His cardiologic evaluation was normal. There were no clinical signs of myocarditis. Three years later he was admitted to the hospital due to a prolonged episode of flu with persistent fever. At that time, his electrocardiogram (ECG) showed junctional rhythm (JR) at 35 bpm. Further ECGs revealed sinus rhythm (SR) with first degree atrio-ventricular block, episodes of sinoatrial (SA) exit blocks, sinus arrests and phases of JR, supporting the diagnosis of sick sinus syndrome (SSS) [1]. Although the boy did not complain of symptoms, Holter monitoring showed frequent pauses of sinus arrest (max interval = 5.4 s) and chronotropic incompetence. At the age of 8 years, he underwent permanent pacemaker (PM) implantation. Although ventricular pacing is less indicated in SSS [2], the patient was treated with VVIR modality because an attempt at right atrial catheter positioning failed, due to inexcitability of the atrium. Since then, the boy has been asymptomatic. Further Holter monitoring showed episodes of paroxysmal atrial fibrillation (Fig. 1) and showed rate responsive pacing with an acceptable mean heart rate of 66 bpm