Intermittent Sinus Pause/Asystole in the Setting of Anticholinergic Overdose

Anticholinergic toxicity typically presents with symptoms of cutaneous vasodilation, delirium, mydriasis, urinary retention, hyperthermia, anhidrosis, and tachycardia. This case report presents a 68-year-old female patient who exhibited some of these signs and symptoms after ingesting an unknown quantity of dicyclomine. However, she displayed one notable exception to the classic toxidrome. On hospital day 2, the patient experienced multiple incidences of prolonged sinus pause, culminating in witnessed asystole lasting 5-10 seconds. The patient continued to have numerous episodes of sinus pause that lasted 5-10 seconds each over the next two days. Treatment involved placement of multiple temporary transvenous pacemakers until the episodes of sinus pause eventually self-resolved, facilitating discharge home on hospital day 6. The patient recovered without any known complications. After considering alternative diagnoses such as sick sinus syndrome, electrolyte derangements, and intracranial hypertension, multiple hospital medical services ultimately attributed the arrhythmia to anticholinergic toxicity. There are no other documented cases of intermittent sinus pause associated with anticholinergic overdose. While rare, clinicians should consider anticholinergic toxicity as a potential cause of intermittent sinus pause, especially in patients taking anticholinergic medications. Increased clinical vigilance could impact treatment decisions, including potentially avoiding unnecessary procedures such as permanent pacemaker placement, if symptoms resolve with cessation of the offending agent.