Cardiac morbidity and mortality associated with the use of lamotrigine

OBJECTIVE: The US Food and Drug Administration recently issued a warning against the use of the antiseizure medication lamotrigine in people at risk of cardiac rhythm and conduction abnormalities. This study assessed the risk of cardiac morbidity and mortality in new users of lamotrigine. METHODS: In a Danish population‐based cohort study, we followed cohort members aged ≥15 years for the first 2 years after they initiated lamotrigine therapy. The main outcomes were cardiac conduction disorders in people without pre‐existing cardiac morbidity and all‐cause mortality in people with pre‐existing cardiac morbidity. Cox proportional hazards models provided hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) for comparison of the risk in current versus past users of lamotrigine. RESULTS: There were 91 949 (36 618 males [39.8%]) new users of lamotrigine (median age = 45.7 years, interquartile range = 32.0–60.2 years). Among users without pre‐existing cardiac disease (n = 86 769), 194 (.23%) developed a cardiac conduction disorder. Comparison of the risk in current and past lamotrigine treatment periods yielded an adjusted HR of new onset cardiac conduction disorder of 1.03 (95% CI = .76–1.40). Among users with pre‐existing cardiac disease (n = 5180), 1150 (22.2%) died. Comparison of the risk in current and past lamotrigine treatment periods yielded an adjusted HR for all cause‐mortality of 1.05 (95% CI = .93–1.19). SIGNIFICANCE: In this large population‐based study, lamotrigine use was associated neither with a risk of cardiac conduction disorders in people without pre‐existing cardiac morbidity nor with all‐cause mortality in people with pre‐existing cardiac morbidity.