Recently, the International League Against Epilepsy (ILAE) / American Epilepsy Society (AES) Task Force met to discuss the food and drug administration (FDA) warning on the cardiac effects of lamotrigine (brand name Lamictal). These concerns originated from lamotrigine’s sodium channel blocking properties. A previous study by Harmer et al. raised the concerns at the FDA, which was followed by an in vitro study from the manufacturer of Lamictal,Glaxo Smith-Kline (GSK) demonstrating that lamotrigine can weakly inhibit cardiac sodium channels, showing class IB antiarrhythmic activity. While lamotrigine has Class 1B antiarrhythmic sodium channel blocking properties, there is no alteration in ventricular conduction (QRS duration) in health individuals, as well as patients with epilepsy and no heart disease. In addition, there is no increased risk of sudden deaths due to cardiac issues in patients taking lamotrigine compared to other antiseizure medications (ASMs). Non-specific electrocardiogram (EKG) abnormalities should not preclude individuals from taking lamotrigine. However, patients with 2nd, 3rd-degree heart block, Brugada syndrome, arrhythmogenic ventricular cardiomyopathy (ARVC), left bundle branch block (LBBB), and right bundle branch block (RBBB) with left anterior or posterior fascicular block should require complete cardiovascular investigation and consultation with a cardiologist prior to initiation of lamotrigine, since they are highest at risk. If used in patients at risk for cardiac conditions, a repeat EKG is recommended at the target dose. Finally, clinicians should consider obtaining an EKG and/or a cardiology consultation in patients taking lamotrigine with sudden onset syncope or pre-syncope with loss of muscular tone without a clear vasovagal or orthostatic cause.
>> International League Against Epilepsy / American Epilepsy Society Task Force Guidelines
Reference:
French JA et al. American Epilepsy Society 2021; Epud ahead of print. Abstract.
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