Rapidly progressive sinus node dysfunction and escape-capture bigeminy in lithium toxicity

Cardiac manifestations of chronic lithium toxicity are uncommon and often overshadowed by neurological symptoms.[1] A 56-year-old woman on chronic lithium monotherapy for bipolar disorder underwent a recent dose escalation from 600 mg/day to 900 mg/day.Over the next 3 days, she developed mild gait instability and confusion, followed by severe fatigue.Initial electrocardiography (ECG) revealed sinus bradycardia at 40 beats/min [Figure 1A].