Cardiac Safety of Lamotrigine Still Awaiting a Verdict

In October 2020 and March 2021, The US Food and Drug Administration (FDA) issued warnings about the arrhythmogenic potential of lamotrigine in patients with heart disease.(1) The agency referenced in vitro results that predicted Class IB antiarrhythmic activity at therapeutic concentrations of lamotrigine due to its sodium channel blocking (SCB) activity. It cautioned that lamotrigine use in at-risk populations could prolong the QRS interval on the ECG and increase the risk of arrhythmias and sudden death. No references to human or animal studies or postmarketing data were cited to support this warning.