Brugada-like Electrocardiographic Pattern Induced by Lamotrigine Toxicity

Unmasking of Brugada syndrome by lamotrigine in a patient with pre-existing epilepsy: A case report with review of the literature

Brugada syndrome is an inherited cardiac channelopathy arising from mutations in voltage-gated cardiac sodium channels. Idiopathic epilepsy portrays a coalescent underlying pathophysiological mechanism pertaining to the premature excitation of neuronal voltage-gated ion channels resulting in the disruption of presynaptic neurons and the unregulated release of excitatory neurotransmitters. The coexistence of epilepsy and Brugada syndrome may be explained by mutations in voltage-gated ion channels, which are coexpressed in cardiac and neural tissue. Moreover, the incidence of sudden unexpected death in epilepsy has been associated with malignant cardiac arrhythmias in the presence of mutations in voltage-gated ion channels. Lamotrigine is an antiepileptic drug that inhibits neuronal voltage-gated sodium channels, thus stabilizing neural impulse propagation and controlling seizure activity in the brain. However, lamotrigine has been shown to inhibit cardiac voltage-gated sodium channels resulting in a potential arrhythmogenic effect and the ability to unmask Brugada syndrome in genetically susceptible individuals. We are reporting a case of a 27-year-old male patient with a background of presumed idiopathic epilepsy who was initiated on lamotrigine therapy resulting in the unmasking of Brugada syndrome and the onset of syncopal episodes. This case provides further evidence for the arrhythmogenic capacity of lamotrigine and highlights the relationship between epilepsy and Brugada syndrome. In this report, we aim to review the current literature regarding the associations between epilepsy and Brugada syndrome and the impact of lamotrigine therapy on such patients.

Epilepsy-Induced High Affinity Blockade of the Cardiac Sodium Current INa by Lamotrigine; A Potential for Acquired Arrythmias

Lamotrigine is widely prescribed to treat bipolar neurological disorder and epilepsy. It exerts its antiepileptic action by blocking voltage-gated sodium channels in neurons. Recently, the US Food and Drug Administration issued a warning on the use of Lamotrigine after observations of conduction anomalies and Brugada syndrome patterns on the electrocardiograms of epileptic patients treated with the drug. Brugada syndrome and conduction disturbance are both associated with alterations of the cardiac sodium current (I_Na) kinetics and amplitude. In this study, we used the patch clamp technique on cardiomyocytes from epileptic rats to test the hypothesis that Lamotrigine also blocks I_Na in the heart. We found that Lamotrigine inhibited 60% of I_Na peak amplitude and reduced cardiac excitability in epileptic rats but had little effect in sham animals. Moreover, Lamotrigine inhibited 67% of I_NaL and, more importantly, prolonged the action potential refractory period in epileptic animals. Our results suggest that enhanced affinity of Lamotrigine for I_Na may in part explain the clinical phenotypes observed in epileptic patients.

The assessment of cardiac risk in patients taking lamotrigine; a systematic review

OBJECTIVE

The Food and Drug Administration (FDA) warned about lamotrigine's arrhythmogenicity based on in vitro data. This systematic review investigates lamotrigine's effect on cardiac conduction and risk of sudden cardiac death (SCD) in individuals with and without cardiovascular disease.

METHODS

We searched Web of Science and PubMed from inception through August 2021. We included studies measuring electrocardiogram (ECG) changes, laboratory abnormalities, or SCD among patients taking lamotrigine. Studies examining sudden unexpected death in epilepsy were excluded for scope. Two reviewers assessed articles and extracted data. We used the Effective Public Healthcare Panacea Project tool to evaluate confidence in evidence.

RESULTS

Eight randomized controlled trials, 9 nonrandomized observational studies, and 24 case reports were identified, with >3054 total participants, >1606 of whom used lamotrigine. One randomized trial of older patients found an average QRS increase of 3.5 +/- 13.1 ms. Fifteen studies reported no changes in ECG parameters. Case reports documented QRS widening (13), Brugada syndrome (6), QTc prolongation (1) and SCD (2), though many ingested toxic quantities of lamotrigine and/or other medications.

CONCLUSIONS

Evidence is insufficient to support the breadth of the FDA warning concerning lamotrigine's cardiac risk. Lamotrigine at therapeutic doses may be associated with modest, non-dangerous QRS widening.

Sinus Bradycardia in an Adolescent Taking Lamotrigine

Lamotrigine is commonly prescribed for the treatment of neurological conditions and is increasingly being prescribed for psychiatric conditions as well. Although largely well tolerated, it is known to have a number of potential side effects, and in March 2021, the FDA issued its most recent warning for the medication due to its increased risk of cardiac arrhythmias. In this report, we describe a case in which an adolescent patient was found to be bradycardic after starting lamotrigine for antidepressant augmentation, with a gradual return to normal heart rate as the medication was subsequently tapered and discontinued. Further research is needed to more accurately estimate the risk of cardiac side effects and to establish appropriate monitoring guidelines for cardiac arrhythmias in those taking lamotrigine.

Reverse translational analysis of clinically reported, lamotrigine-induced cardiovascular adverse events using the halothane-anesthetized dogs

Lamotrigine has been used for patients with epilepsy and/or bipolar disorder, overdose of which induced the hypotension, elevation of the atrial pacing threshold, cardiac conduction delay, wide complex tachycardia, cardiac arrest and Brugada-like electrocardiographic pattern. To clarify how lamotrigine induces those cardiovascular adverse events, we simultaneously assessed its cardiohemodynamic and electrophysiological effects using the halothane-anesthetized dogs (n = 4). Lamotrigine was intravenously administered in doses of 0.1, 1 and 10 mg/kg/10 min under the monitoring of cardiovascular variables, possibly providing subtherapeutic to supratherapeutic plasma concentrations. The low or middle dose of lamotrigine did not alter any of the variables. The high dose significantly delayed the intra-atrial and intra-ventricular conductions in addition to the prolongation of ventricular effective refractory period, whereas no significant change was detected in the other variables. Lamotrigine by itself has relatively wide safety margin for cardiohemodynamics, indicating that clinically reported hypotension may not be induced through its direct action on the resistance arterioles or capacitance venules. The electrophysiological effects suggested that lamotrigine can inhibit Na⁺ channel in the in situ hearts. This finding may partly explain the onset mechanism of lamotrigine-associated cardiac adverse events in the clinical cases. In addition, elevation of J wave was induced in half of the animals, suggesting that lamotrigine may have some potential to unmask Brugada electrocardiographic genotype in susceptible patients.

Lamotrigine induced Brugada-pattern in a patient with genetic epilepsy associated with a novel variant in SCN9A

BACKGROUND

A 30-year-old man presented with intellectual disability associated with epilepsy. The epilepsy was initially treated with sodium valproate and since he was 28 years-old with lamotrigine. With the addition of lamotrigine, a pattern of Brugada syndrome appeared on the electrocardiogram. The family history was positive for epilepsy from the motheŕs side, who had never been treated with lamotrigine.

OBJECTIVE

Determine the genetic cause of the intellectual disability, epilepsy and Brugada syndrome of the patient and try to establish a possible correlation between the genetic background and the Brugada syndrome pattern under lamotrigine treatment.

METHODS

A standard karyotype, array comparative genomic hybridization and two different NGS panels have done to the index case to identify the genetic causes of the intellectual disability, epilepsy and Brugada syndrome pattern.

RESULTS

Genetic analyses in the family identified a de novo duplication of 1.3 Mb in 8p21.3 as well as two novel heterozygous rare variants in SCN9A and AKAP9 genes, both inherited from the mother.

CONCLUSION

We hypothesize that in this family the SCN9A variant was responsible for the epileptic syndrome. In addition, given that SCN9A is lightly expressed in the heart tissue, we postulate that this SCN9A variant, alone or in combination with AKAP9 variant, might be responsible for the Brugada pattern when challenged by lamotrigine.

Lamotrigine Toxicosis Treated with Intravenous Lipid Emulsion Therapy in a Dog

A female spayed dachshund/mixed-breed dog was evaluated following ingestion of lamotrigine tablets with subsequent rapid onset of vomiting, diarrhea, and generalized tremoring. On initial examination, the dog was moderately obtunded and nonambulatory with intermittent myoclonus and hyperesthesia. Electrocardiogram revealed sinus tachycardia with prolongation of the QT interval. Intravenous lipid emulsion (ILE) infusion was initiated, with reduction in tremoring and improved patient mentation being noted after ∼20 min of therapy. An elevated cardiac troponin I value measured at 1.02 ng/mL the day after presentation. Serum toxicological assay revealed marked reduction in serum lamotrigine levels following ILE and continued reduction during hospitalization. The dog's clinical signs resolved, corrected QT interval returned to normal, and the patient was discharged 38 hr after presentation. Individual cases of lamotrigine toxicosis have not been fully reported in veterinary literature. This case report documents the rapid onset of clinical signs including neurologic dysfunction, cardiac arrhythmias, and transient corrected QT prolongation. Serial serum concentrations of lamotrigine showed a rapid reduction with ILE therapy and corresponded with clinical recovery, suggesting efficacy of ILE treatment in this case.

Drug-induced fatal arrhythmias: Acquired long QT and Brugada syndromes

Since the early 1990s, the concept of primary "inherited" arrhythmia syndromes or ion channelopathies has evolved rapidly as a result of revolutionary progresses made in molecular genetics. Alterations in genes coding for membrane proteins such as ion channels or their associated proteins responsible for the generation of cardiac action potentials (AP) have been shown to cause specific malfunctions which eventually lead to cardiac arrhythmias. These arrhythmic disorders include congenital long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, short QT syndrome, progressive cardiac conduction disease, etc. Among these, long QT and Brugada syndromes are the most extensively studied, and drugs cause a phenocopy of these two diseases. To date, more than 10 different genes have been reported to be responsible for each syndrome. More recently, it was recognized that long QT syndrome can be latent, even in the presence of an unequivocally pathogenic mutation (silent mutation carrier). Co-existence of other pathological conditions in these silent mutation carriers may trigger a malignant form of ventricular arrhythmia, the so called torsade de pointes (TdP) that is most commonly brought about by drugs. In analogy to the drug-induced long QT syndrome, Brugada type 1 ECG can also be induced or unmasked by a wide variety of drugs and pathological conditions; so physicians may encounter patients with a latent form of Brugada syndrome. Of particular note, Brugada syndrome is frequently associated with atrial fibrillation whose therapeutic agents such as Vaughan Williams class IC drugs can unmask the dormant and asymptomatic Brugada syndrome. This review describes two types of drug-induced arrhythmias: the long QT and Brugada syndromes.

Brugada Pattern Caused by a Flecainide Overdose

BACKGROUND

Brugada pattern can be found on the electrocardiogram (ECG) of patients with altered mental status, usually with fever or drug intoxication. Diagnosis remains challenging, because the ECG changes are dynamic and variable. In addition, triggers are not always clearly identified. In patients with atrial fibrillation (AF), the use of class IC antidysrhythmic drugs can unmask a Brugada pattern on the ECG, especially if combined with other medications acting on sodium channels.

CASE REPORT

A 62-year-old man with a medical history of AF was admitted to our emergency department for altered mental status. The ECG at the time of admission showed a Brugada pattern, triggered by a flecainide overdose (about 1 g), in association with an unknown dose of lamotrigine and quetiapine. After discontinuation of all medications, the Brugada pattern disappeared and his ECG showed no abnormalities. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: In patients with AF, the use of class IC antidysrhythmic drugs, if overdosed, can trigger a Brugada ECG pattern, and therefore it can increase the risk for malignant dysrhythmias. It is important to provide, to all patients with a Brugada ECG pattern, a list of drugs to avoid, and to underline the synergistic interplay between drugs, taking into consideration all patients' comorbidities.

Safety profile of lamotrigine in overdose

BACKGROUND

Lamotrigine is an anticonvulsant as well as a mood stabilizer. Apart from its established use in the treatment of epilepsy, there has been an expansion of its use in the treatment of mental disorders. Patients with epilepsy as well as those with mental disorders are at increased risk of deliberate drug overdoses. An evidence base for the safety profile of lamotrigine in overdose is an essential tool for prescribers. The objective of this study was to carry out a narrative synthesis of the existing evidence for the safety profile of lamotrigine in overdose.

METHODS

A systematic search was conducted of EMBASE (1974 to December 2015), MEDLINE (1946 to December 2015), PsycINFO (1806 to December 2015) and CINAHL (1981 to December 2015) databases. Studies were included in which there was a deliberate or accidental single drug overdose of lamotrigine, with its toxic effects described. Studies that did not involve an overdose were excluded. A narrative synthesis of the described toxic effects was carried out.

RESULTS

Out of 562 articles identified, 26 studies were included, mainly in the form of case reports and series. The most commonly described toxic effects of lamotrigine were on the central nervous system, specifically seizures, movement disorders and reduced consciousness. Other toxic effects included QTc interval and QRS complex prolongations, hypersensitivity reactions, serotonin syndrome as well as rhabdomyolysis possibly due to seizures and/or agitation. Deaths were recorded in two studies, with cardiovascular and neurological toxic effects described.

CONCLUSIONS

Even though lamotrigine has been reported to be well tolerated, there is a risk of toxic effects which can be life threatening in overdose. This needs to be borne in mind when prescribing to patients at an increased risk of deliberate drug overdose.

The heart of epilepsy: Current views and future concepts

Cardiovascular (CV) comorbidities are common in people with epilepsy. Several mechanisms explain why these conditions tend to co-exist including causal associations, shared risk factors and those resulting from epilepsy or its treatment. Various arrhythmias occurring during and after seizures have been described. Ictal asystole is the most common cause. The converse phenomenon, arrhythmias causing seizures, appears extremely rare and has only been reported in children following cardioinihibitory syncope. Arrhythmias in epilepsy may not only result from seizure activity but also from a shared genetic susceptibility. Various cardiac and epilepsy genes could be implicated but firm evidence is still lacking. Several antiepileptic drugs (AEDs) triggering conduction abnormalities can also explain the co-existence of arrhythmias in epilepsy. Epidemiological studies have consistently shown that people with epilepsy have a higher prevalence of structural cardiac disease and a poorer CV risk profile than those without epilepsy. Shared CV risk factors, genetics and etiological factors can account for a significant part of the relationship between epilepsy and structural cardiac disease. Seizure activity may cause transient myocardial ischaemia and the Takotsubo syndrome. Additionally, certain AEDs may themselves negatively affect CV risk profile in epilepsy. Here we discuss the fascinating borderland of epilepsy and cardiovascular conditions. The review focuses on epidemiology, clinical presentations and possible mechanisms for shared pathophysiology. It concludes with a discussion of future developments and a call for validated screening instruments and guidelines aiding the early identification and treatment of CV comorbidity in epilepsy.

Evolving Electrocardiographic Changes in Lamotrigine Overdose: A Case Report and Literature Review

Lamotrigine overdose usually follows a benign pattern, and the majority of cases reported involve a co-ingestant. Prior reports have suggested the possible use of intravenous lipid emulsion in cases of severe sodium channel blockade. We describe the electrocardiographic changes in a massive lamotrigine overdose treated with intravenous lipid emulsion. A 36-year-old male with bipolar disorder ingested 13.5 g of lamotrigine in a suicidal attempt. The lamotrigine level was 78.0 μg/mL. Comprehensive drug screen was negative for all screened compounds. The electrocardiogram demonstrated a prolonged QRS complex and signs suggestive of sodium channel blockade. Refractory to treatment with sodium bicarbonate was treated with intravenous lipid emulsion, with immediate resolution of the electrocardiographic changes. Lamotrigine inhibits the voltage-gated sodium channel opening, attenuating the release of excitatory neurotransmitters. Cardiac intraventricular conduction could be delayed in cases of lamotrigine overdose resulting in QRS and QTc prolongation and R waves >3 mm in leads I and aVR. A potential role for intravenous lipid emulsion therapy has been described in patients with toxic levels of lamotrigine and electrocardiographic changes refractory to the treatment with sodium bicarbonate. Intravenous lipid emulsion has been successfully used in the treatment of lamotrigine cardiac toxicity.

Polytherapy with sodium channel-blocking antiepileptic drugs is associated with arrhythmogenic ST-T abnormality in patients with epilepsy

PURPOSE

Recent reports have documented the appearance of Brugada-type ST elevation in cases of overdose of antiepileptic drugs (AEDs). However, little is known about changes on electrocardiographs (ECGs) during AED use at therapeutic doses. AEDs may cause Brugada-type ST elevation or J-wave-like intraventricular conduction delays through an ion channel-blocking effect. In the present study, we sought to elucidate ECG abnormalities in patients on AED therapy.

METHODS

The study population consisted of 120 consecutive patients with epilepsy who continued to take AEDs and had ECGs recorded during these therapies. Their clinical background and ECGs were retrospectively analyzed. Brugada-type ST elevation was classified according to the consensus report on Brugada syndrome. A J-wave-like ECG abnormality was defined as the appearance of notching or slurring of the QRS complex (>0.1mV) in the inferior/lateral leads.

RESULTS

Of the 120 patients, 15 (12.5%) exhibited Brugada-type ST elevation and 35 (29.2%) showed a J-wave-like ECG abnormality. Polytherapy with sodium channel-blocking AEDs (e.g., carbamazepine, phenytoin, lamotrigine) was more frequently observed in patients with Brugada-type ST elevation (p=0.048). However, the serum concentrations of these medicines did not differ between patients with and without ECG abnormalities (carbamazepine: 7.9±4.1 vs. 7.2±5.9μg/dL; phenytoin: 12.7±4.1 vs. 15.5±9.5μg/dL, NS).

CONCLUSION

ST-T abnormalities were frequently seen in patients using AEDs. The presence of Brugada-type ST elevation was associated with polytherapy with sodium channel-blocking AEDs.

Drug-induced cerebellar ataxia: a systematic review

BACKGROUND AND OBJECTIVES

Cerebellar ataxia can be induced by a large number of drugs. We here conducted a systemic review of the drugs that can lead to cerebellar ataxia as an adverse drug reaction (ADR).

METHODS

We performed a systematic literature search in Pubmed (1966 to January 2014) and EMBASE (1988 to January 2014) to identify all of the drugs that can have ataxia as an ADR and to assess the frequency of drug-induced ataxia for individual drugs. Furthermore, we collected reports of drug-induced ataxia over the past 20 years in the Netherlands by querying a national register of ADRs.

RESULTS

Drug-induced ataxia was reported in association with 93 individual drugs (57 from the literature, 36 from the Dutch registry). The most common groups were antiepileptic drugs, benzodiazepines, and antineoplastics. For some, the number needed to harm was below 10. Ataxia was commonly reversible, but persistent symptoms were described with lithium and certain antineoplastics.

CONCLUSIONS

It is important to be aware of the possibility that ataxia might be drug-induced, and for some drugs the relative frequency of this particular ADR is high. In most patients, symptoms occur within days or weeks after the introduction of a new drug or an increase in dose. In general, ataxia tends to disappear after discontinuation of the drug, but chronic ataxia has been described for some drugs.

A case series of patients with lamotrigine toxicity at one center from 2003 to 2012

INTRODUCTION

Lamotrigine is a phenyltriazine compound that inhibits voltage-gated sodium channels, decreasing release of glutamate and aspartate, and inhibits serotonin, norepinephrine and dopamine reuptake. Reports of toxicity in the literature are limited to case reports and primarily involve coingestants. This case series is intended to report the clinical manifestations of lamotrigine toxicity.

METHODS

This retrospective case series from 2003 to 2012 studies the effects of lamotrigine toxicity when not confounded by coingestants. Admission records at an inpatient toxicology center were reviewed for lamotrigine-only exposure based on history with supporting laboratory data when available. After identification, these charts were reviewed again to characterize vital signs, neurological examination findings, specific laboratory and electrocardiography parameters, and complications.

RESULTS

Fifty-seven patients were identified with possible lamotrigine toxicity. Nine patients, including three toddlers, had lamotrigine-only ingestions. Three of these patients had seizures, four were hypertensive, five were tachycardic, and four experienced tachypnea. Mental status was altered in all nine (depressed (n = 4), agitated (n = 5) or both (n = 3)). Five patients were hyperreflexic and experienced intermittent myoclonus, and two had inducible clonus. On electrocardiogram, two patients experienced QRS prolongation (114-116 ms), and four had QTc prolongation (463-586 ms). No patient had life-threatening symptoms or signs. Serum levels of lamotrigine were available in seven patients, and averaged 35.4 mg/L (17-90 mg/L). The therapeutic range for sLTG is 3-14 mg/L.

CONCLUSIONS

Lamotrigine toxicity manifested with minor-moderate neurologic and/or electrocardiographic effects. Toxicity reflects the known pharmacologic actions of lamotrigine: serotonin, norepinephrine and dopamine reuptake inhibition, and sodium channel blockade.

Severe sodium channel blockade and cardiovascular collapse due to a massive lamotrigine overdose

BACKGROUND

Cardiac arrest due to lamotrigine (LTG) has been reported after co-ingestion with bupropion, but severe sodium channel blockade in the absence of other toxins has not been described. We report a case of cardiac arrest and status epilepticus following a massive LTG overdose.

CASE REPORT

A 48 year-old female was brought to the ED with seizure-like activity subsequent to ingesting 7.5 g of LTG. Vital signs were HR 131, BP 107/68, T 99.4°F, RR 16. She was intubated in the ED for a low GCS. Initial ECG demonstrated a narrow-complex normal sinus rhythm, and her labs were unremarkable. Three hours after intubation she developed status epilepticus, and a pulseless wide-complex tachycardia. She was aggressively resuscitated during which time pulses were periodically reestablished, but lost each time seizures recurred. She was not stabilized until the convulsions were terminated with vecuronium. Her post-resuscitation ECG demonstrated a junctional tachycardia with a 3 mm R-wave in aVR. The LTG level was 74.7 mcg/ml (therapeutic: 3-14 mcg/ml). Comprehensive LC-MS/MS drug screen was negative for all screened compounds.

DISCUSSION

This is the first report of cardiovascular collapse due to LTG with the highest drug concentration to date.

CONCLUSION

The degree of neurologic and cardiovascular toxicity seen in this case are novel and illustrate the potential for severe sodium channel blockade after massive LTG poisonings. Drug levels are not clinically relevant in the acute setting due to the time delay in obtaining results, and recurrent seizure activity may be the only clinical finding that precedes severe cardiac toxicity.