Brugada-like electrocardiographic pattern induced by lamotrigine toxicity.
BACKGROUND
Brugada syndrome, a recognized cause of sudden cardiac death, is due to a defect of cardiac sodium channels. Many pharmotherapeutic agents induce an electrocardiographic (ECG) pattern that can be confused with Brugada syndrome in patients who may not have the disease.


METHODS
A 22-year-old Hispanic female presented for emergency evaluation with ataxia and alterations in consciousness. Her medical history was significant for temporal lobe epilepsy, treated with lamotrigine, a phenyltriazine agent known to block neuronal voltage-gated sodium channels. There was no family history of sudden cardiac death. Initial laboratory data, neuroimaging, and echocardiography were unremarkable. Her ECG on presentation was concerning for Brugada pattern. Because of the nonspecific ECG finding, the patient underwent procainamide challenge, which was initially felt to be positive. Serum lamotrigine level was subsequently reported in the toxic range at 20.4 μg/mL (therapeutic range, 1-4 μg/mL). Repeated procainamide challenge was performed with lamotrigine levels below the therapeutic range (0.2 μg/mL) and failed to show diagnostic ECG changes.


CONCLUSIONS
Lamotrigine, at toxic levels, may lose specificity and exert an effect on cardiac sodium channels, a phenomenon that has not been previously described. Given previous reports of associations between the drug-induced Brugada ECG pattern and ventricular dysrhythmias, clinicians should be aware of this potential effect.
Strimel
William J
WJ
Section of Cardiac Electrophysiology and Pacing, Division of Cardiology, Scott and White Clinic, Department of Neurology, Scott and White Neuroscience Institute, Texas A&M University Health Science Center, Temple, TX, USA. wstrimel@swmail.sw.org
Woodruff
Amy
A
Cheung
Peter
P
Kirmani
Batool F
BF
Stephen Huang
Shoei K
SK
D000927:Anticonvulsants / Q000009:adverse effects*; D053840:Brugada Syndrome / Q000139:chemically induced* / Q000503:physiopathology; D002121:Calcium Channel Blockers / Q000009:adverse effects* / Q000097:blood; D004833:Epilepsy, Temporal Lobe / Q000188:drug therapy; D005260:Female; D006801:Humans; D000077213:Lamotrigine; D011342:Procainamide; D015222:Sodium Channels / Q000187:drug effects; D014227:Triazines / Q000009:adverse effects* / Q000097:blood; D028761:Withholding Treatment; D055815:Young Adult
D000927:Anticonvulsants; D002121:Calcium Channel Blockers; D015222:Sodium Channels; D014227:Triazines; D011342:Procainamide; D000077213:Lamotrigine