A Case of Sick Sinus Syndrome With Prolonged Asystole Masquerading as a Transient Ischemic Attack

Sick sinus syndrome (SSS) is a term used to describe dysfunction of the sinoatrial (SA) node that can lead to various cardiac arrhythmias that predominately manifest in the elderly. Commonly implicated arrhythmias vary from inappropriate bradycardia, tachycardia, sinus pauses, and rarely sinus arrest. Despite being a common reason for permanent pacemaker implantation, little is known regarding the incidence of SSS and there is even less reporting on SSS complicated by prolonged asystole. We present a case highlighting an infrequently observed manifestation of SSS with recurrent, prolonged ventricular asystolic episodes that were causing previously unexplained episodes of confusion and agonal breathing. Our patient was a 75-year-old male with a past medical history of hypertension, dyslipidemia, and prior transient ischemic attacks (TIAs) that presented after an acute mental status change. The initial leading differential diagnosis was believed to be a TIA and he was admitted to neurology service for further evaluation. The patient had recurring episodes of confusion associated with agonal breathing that upon closer review of the cardiac telemetry revealed sinus bradycardia to the 40s interrupted by several prolonged episodes of asystole, the longest lasting 20 seconds. Due to his symptoms and to avoid potential deterioration resulting in hemodynamic instability, the electrophysiology service urgently placed a temporary transvenous pacemaker and then later implanted a leadless pacemaker. On outpatient follow-up, he no longer had episodes of confusion, and no further asystolic episodes were noted on his device check.