Epilepsy is a risk factor for sudden cardiac arrest in the general population

Antiseizure Medications and Sudden Unexpected Death in Epilepsy: An Updated Review

Sudden unexpected death in epilepsy (SUDEP) is responsible for most epilepsy-related deaths. It is mainly related to unwitnessed nocturnal convulsions, either focal to bilateral or generalised tonic-clonic seizures (TCS). Targeted preventive strategies are currently lacking as underlying mechanisms are largely unknown. Antiseizure medications (ASMs) modulate SUDEP risk through seizure reduction, but it is yet undetermined whether individual ASMs or other medications could also influence the internal SUDEP cascade. Seizure detection devices (SDD) may offer an alternative strategy by preventing TCS from being unwitnessed. Here, we critically evaluated the current evidence on the influence of ASMs, non-epilepsy concomitant drugs and SDD on SUDEP occurrence. We found no robust evidence for the effect of starting ASMs on SUDEP beyond TCS control, but we found some indications of a protective effect for polytherapy. We found no signs that specific ASMs exert a risk for SUDEP. One study suggested a possible protective effect of levetiracetam requiring further investigation. Only a few small studies addressed the association between non-epilepsy concomitant drugs and SUDEP, with no consistent effect for psychotropic medications and one more extensive study suggesting a lower risk among statin users. We only found indirect evidence indicating a protective effect for enhancing nocturnal supervision without explicitly addressing the impact of SDD on SUDEP occurrence. Further work is needed to explore the potential of ASMs and other interventions to modulate SUDEP risk, and they should accurately account for TCS frequency, polypharmacy and markers of non-adherence.

Brain and Heart Interactions Delineating Cardiac Dysfunction in Four Common Neurological Disorders: A Systematic Review and Meta-analysis

Neurological and cardiovascular disorders are the leading causes of morbidity and mortality worldwide. While the effects of cardiovascular disease (CD) on the nervous system are well understood, understanding of the reciprocal relationship has only recently become clearer. Based on disability-adjusted life years, this systematic review and meta-analysis present the pooled incidence and association of CD in 4 selected common, noncommunicable neurological disorders: (1) migraine, (2) Alzheimer disease and other dementias, (3) epilepsy, and (4) head injury. Sixty-five studies, including over 4 and a half million patients, were identified for inclusion in this review. Among the 4 neurological disorders, the majority of patients (89.4%) had epilepsy, 9.6% had migraine, and 0.97% had head injury. Alzheimer disease and other dementias were reported in only 0.02% of patients. The pooled effect estimates (incidence and association) of CD in the 4 neurological disorders was 10% (95% CI: 5.8%-16.9%; I2 = 99.94%). When stratified by the neurological disorder, head injury was associated with the highest incidence of CD (28%). The 4 neurological disorders were associated with a 2-fold increased odds for developing CD in comparison to patients without neurological disorders. Epilepsy was associated with the greatest increased odds of developing CD (odds ratio: 2.25; 95% CI: 1.82-2.79; P = 0.04). In studies that reported this variable, the pooled hazard ratio was 1.64 (95% CI: 1.38-1.94), with head injury having the highest hazard ratio (2.17; 95% CI: 1.30-3.61). Large prospective database studies are required to understand the long-term consequences of CD in patients with neurological disorders.

The Epileptic Heart Syndrome: Epidemiology, pathophysiology and clinical detection

Population studies report elevated incidence of cardiovascular events in patients with chronic epilepsy. Multiple pathophysiologic processes have been implicated, including accelerated atherosclerosis, myocardial infarction, altered autonomic tone, heart failure, atrial and ventricular arrhythmias, and hyperlipidemia. These deleterious influences on the cardiovascular system have been attributed to seizure-induced surges in catecholamines and hypoxemic damage to the heart and coronary vasculature. Certain antiseizure medications can accelerate heart disease through enzyme-inducing increases in plasma lipids and/or increasing risk for life-threatening ventricular arrhythmias as a result of sodium channel blockade. In this review, we propose that this suite of pathophysiologic processes constitutes "The Epileptic Heart Syndrome." We further propose that this condition can be diagnosed using standard electrocardiography, echocardiography, and lipid panels. The ultimate goal of this syndromic approach is to evaluate cardiac risk in patients with chronic epilepsy and to promote improved diagnostic strategies to reduce premature cardiac death.

The role of the adenosine system in epilepsy and its comorbidities

Epilepsy is one of the most serious and common chronic neurological conditions, characterised by recurrent hypersynchronous electrical activity in the brain that lead to seizures. Despite over 50 million people being affected worldwide, only ~70% of people with epilepsy have their seizures successfully controlled with current pharmacotherapy, and many experience significant psychiatric and physical comorbidities. Adenosine, a ubiquitous purine metabolite, is a potent endogenous anti-epileptic substance that can abolish seizure activity via the adenosine A1 G protein-coupled receptor. Activation of A1 receptors decreases seizure activity in animal models, including models of drug-resistant epilepsy. Recent advances have increased our understanding of epilepsy comorbidities, highlighting the potential for adenosine receptors to modulate epilepsy-associated comorbidities, including cardiovascular dysfunction, sleep and cognition. This review provides an accessible resource of the current advances in understanding the adenosine system as a therapeutic target for epilepsy and epilepsy-associated comorbidities. LINKED ARTICLES: This article is part of a themed issue Therapeutic Targeting of G Protein-Coupled Receptors: hot topics from the Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists 2021 Virtual Annual Scientific Meeting. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.14/issuetoc.

Cardiovascular Implications of Epilepsy: Unraveling the Elevated Risk of Mortality

Introduction Epilepsy is a complex prevalent seizure disorder impacting a significant number of individuals worldwide. Those with epilepsy face the possibility of experiencing sudden unexpected death in epilepsy (SUDEP). When examining the relationship between epilepsy and SUDEP, cardiac-related deaths (CRD) may be considered a driving force. We hypothesize that patients with epilepsy are at higher risk of CRD than those without epilepsy. While utilizing the National Institutes of Health (NIH) All of Us Researcher Program (AoU) database, we also explored the relationship between epilepsy and cardiac-related deaths and propose potential connective mechanisms between the two conditions. Methods Baseline data from the National Institutes of Health All of Us Researcher Program was used to evaluate the relationship between cardiac-related deaths and epilepsy. A retrospective cohort study was conducted where individuals with epilepsy and without epilepsy were matched by inclusion and exclusion criteria including death, cardiac-related death, and epilepsy. Additionally, the prevalence of cardiac-related deaths was compared to neurological, respiratory, and hepatic-related deaths for patients with epilepsy to identify emerging causes of SUDEP. Results Among patients with a history of epilepsy, the prevalence of CRD was 45 (17.3%) compared to 305 (11%) in the control group. This difference was statistically significant by p<0.0042 with an odds ratio (OR)=1.698, 95%CI 1.214-2.379. Additionally, there was the highest number of significant cardiac-related deaths amongst patients with epilepsy compared to patients without epilepsy as opposed to different mechanisms of death such as acute respiratory failure, acute hepatic failure, and hypoxic brain injury. Conclusion This study indicates that epileptic patients have a statistically significant higher prevalence of cardiac-related deaths. Additionally, cardiac-related deaths constitute a significantly higher proportion of fatalities amongst patients with epilepsy compared to other causes of SUDEP. Potential mechanisms for these findings may include seizure-induced arrhythmias, hypoxia-induced cardiac arrest, autonomic dysregulation, and neurotransmitter disequilibrium. The results of our study suggest promising directions for future research in identifying predictors of cardiac-related deaths with proposed cardiac monitoring protocols as preventative strategies for epileptic patients in efforts to reduce the prevalence of SUDEP.

Association of minor electrocardiographic (ECG) abnormalities with epilepsy duration in children: A manifestation of the epileptic heart?

PURPOSE

Cardiac abnormalities resulting from chronic epilepsy ("the epileptic heart") constitute a well-recognized comorbidity. However, the association of cardiac alterations with epilepsy duration remains understudied. We sought to evaluate this association using electrocardiogram (ECG).

METHODS

We prospectively enrolled children between 1 months and 18 years of age without known cardiac conditions or ion channelopathies during routine clinic visits. ECGs were categorized as abnormal if there were alterations in rhythm; PR, QRS, or corrected QT interval; QRS axis or morphology; ST segment or T wave. An independent association between ECG abnormalities and epilepsy duration was evaluated using multivariable logistic regression modeling.

RESULTS

213 children were enrolled. 100 ECGs (47%) exhibited at least one alteration; most commonly in the ST segment (37, 17%) and T wave (29, 11%). Children with normal ECGs had shorter epilepsy duration as compared to those with ECG abnormalities (46 [18-91] months vs. 73 [32-128 months], p = 0.004). A multivariable logistic regression model demonstrated that increasing epilepsy duration was independently associated with the presence of ECG abnormalities (OR=1.09, 95% CI=1.02-1.16, p = 0.008), adjusted for seizure frequency, generalized tonic-clonic/focal to bilateral tonic-clonic seizures as the predominant seizure type, and number of channel-modifying anti-seizure medications. Increasing epilepsy duration was also independently associated with the presence of ST/T wave abnormalities (OR=1.09, 95% CI=1.01-1.16, p = 0.017), adjusted for the same covariates.

SIGNIFICANCE

Increasing epilepsy duration is independently associated with the presence of minor ECG abnormalities. Additional studies are needed to evaluate whether this finding may represent a manifestation of the "epileptic heart".

Short-term effects of transcutaneous auricular vagus nerve stimulation on T-wave alternans in people with focal epilepsy - An exploratory pilot study

High levels of T-wave alternans (TWA) are linked to an increased risk of sudden cardiac death. People with epilepsy display elevated TWA levels that are decreased by chronic vagus nerve stimulation via implanted devices after 2-4 weeks or later. Our objective was to explore short-term effects of transcutaneous auricular vagus nerve stimulation (tVNS) on TWA. Five patients (3 female) with focal epilepsy undergoing video-EEG monitoring were included. TWA levels were determined using a one-channel modified lead I ECG via an open-source TWA-algorithm on two consecutive days, 1 h before, during and after tVNS via the left auricle. Data are given as mean ± SE. Mean TWA at baseline was 3.8 ± 0.4 µV and 3.0 ± 0.6 µV during stimulation on day 2. Stimulations on the second day were associated with TWA reductions by 22 ± 13 % that exceeded stimulation effects on the first day relative to baseline (p < 0.05). Linear mixed-models revealed effects of both stimulation (p < 0.05) and stimulation number (p < 0.005). Normalized TWA showed reproducible peak reductions at both days within 35 min after the initiation of tVNS (p < 0.05). Our observations suggest that tVNS has short-term effects on TWA, supporting the notion that vagus nerve stimulation has a beneficial impact on electrical cardiac properties.

Epilepsy and long-term risk of arrhythmias

BACKGROUND AND AIMS

Previous evidence has mainly supported transient changes in cardiac function during interictal or peri-ictal phases in people with epilepsy, but the long-term risk of cardiac arrhythmias is poorly described. This study aimed to assess the long-term association of epilepsy with cardiac arrhythmias, considering the potential role of genetic predisposition and antiseizure medications (ASMs) in any associations observed.

METHODS

This population-based study evaluated UK Biobank data for individuals recruited between 2006 and 2010. Cox proportional hazards models and competing risk models were used to examine the association of epilepsy history with the long-term incidence risk of cardiac arrhythmias and arrhythmias subtypes. Polygenic risk scores (PRS) were calculated to investigate the effect of genetic susceptibility. The role of ASMs was also evaluated by integrating observational and drug target Mendelian randomization (MR) evidence.

RESULTS

The study included 329 432 individuals, including 2699 people with epilepsy. Compared with those without epilepsy, people with epilepsy experienced an increased risk of all cardiac arrhythmias [hazard ratio (HR) 1.36, 95% confidence interval (CI) 1.21-1.53], atrial fibrillation (HR 1.26, 95% CI 1.08-1.46), and other cardiac arrhythmias (HR 1.56, 95% CI 1.34-1.81). The associations were not modified by genetic predisposition as indicated by PRS. Competing and sensitivity analyses corroborated these results. Individuals with epilepsy using ASMs, especially carbamazepine and valproic acid, were at a higher risk for cardiac arrhythmias. This observation was further supported by drug target MR results (PSMR < .05 and PHEIDI > .05).

CONCLUSION

This study revealed the higher risk of cardiac arrhythmias persists long term in people with epilepsy, especially among those using carbamazepine and valproic acid. These findings highlight the need for regular heart rhythm monitoring and management in people with epilepsy in order to reduce the risk of further cardiovascular complications.

Black-Box Warnings of Antiseizure Medications: What is Inside the Box?

Antiseizure medications can cause serious adverse reactions and have deleterious drug interactions that often complicate the clinical management of patients. When the US Food and Drug Administration (FDA) wants to alert healthcare providers and patients about the risk of potentially serious or fatal drug reactions, the FDA requires the manufacturers of these medications to format these warnings within a "black-box" border, and prominently display this box on the first section of the package insert; such warnings are called "black-box warnings (BBWs)". The BBW is a way for the FDA to urge physicians to evaluate patients more rigorously and carefully weigh the risks and benefits, before prescribing medication that has the potential to cause serious adverse reactions, and to formulate a plan for close monitoring during therapy. The FDA BBW provides the extra layer of safety but many healthcare providers fail to comply with these warnings. Currently, there are 26 FDA-approved antiseizure medications in the US market, 38% of which have received BBWs, and most of the antiseizure medications with BBWs are older-generation drugs. Some antiseizure medications have multiple BBWs; for example, valproic acid has three BBWs including hepatotoxicity, fetal risk, and pancreatitis, carbamazepine has BBWs of serious skin and hematological reactions, and felbamate also has two BBWs including hepatic failure and aplastic anemia. The purpose of this review is to provide insight into each BBW received by antiseizure medications and discuss the FDA recommendations for evaluating the drug benefit/risk, and for monitoring parameters before the initiation of and during treatment.

Scoping review of rational polytherapy in patients with drug-resistant epilepsy

There is a paucity of literature regarding the optimal selection of combination antiseizure medications (ASMs) for drug-resistant epilepsy (DRE). The aim of this scoping review is to evaluate current evidence related to "rational polytherapy" among adults with DRE. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Scoping Reviews (PRISMA-SCr) guidelines, PubMed, ProQuest, CINAHL, and Cochrane databases were searched using DRE- and polytherapy-related keywords. The exclusion criteria applied included: non-English; non-human studies; non-research studies; participants less than 18 years; status epilepticus; ASM monotherapy; and certain ASMs. In Covidence, two researchers independently reviewed articles for inclusion at each phase, with a third resolving conflicts. Data were extracted, with quality appraisal using the Mixed Methods Appraisal Tool (MMAT). Of the 6477 studies imported for screening, 33 studies were included. Clinical, humanistic, and economic outcomes were reported by 26, 12, and one study, respectively. Common efficacy-related clinical outcomes included ≥50% reduction in seizure frequency (n = 14), seizure freedom (n = 14), and percent reduction in seizure frequency (n = 8). Common humanistic outcomes included quality of life (n = 4), medication adherence (n = 2), sleep-related outcomes (n = 2), and physician and patient global assessments (n = 2). The economic study reported quality-adjusted life years. The median MMAT score was 80 (range: 60-100). Two studies referenced the standard definition of DRE, whereas five studies did not specifically define DRE. Gaps in the literature include limited generalizability, minimal reports in pregnancy, and lack of optimal ASM combinations, among others. Strengths of the evidence include addressing a variety of outcomes. Inconsistent definitions of DRE, small sample sizes, and heterogeneity among studies limit the ability to draw meaningful conclusions. Optimal combinations of ASMs for rational polytherapy for DRE is unclear.

Risk of out-of-hospital cardiac arrest in patients with epilepsy and users of antiepileptic drugs

Aims

A few studies suggested that epilepsy and antiepileptic drugs with sodium channel‐blocking properties were independently associated with out‐of‐hospital cardiac arrest (OHCA). However, these findings have not yet been replicated.

Methods

Using Danish registries, we conducted a nested case–control study in a cohort of individuals between 1 June 2001 and 31 December 2015. Cases were defined as OHCA from presumed cardiac causes, and were matched with non‐OHCA‐controls based on sex, and age on the date of OHCA. Exposure of interest was epilepsy or antiepileptic drug use. To study the association between individual antiepileptic drug use and the rate of OHCA, we compared each antiepileptic drug with valproic acid. Cox regression with time‐dependent covariates was conducted to calculate hazard ratio (HR) and 95% confidence interval (CI).

Results

We identified 35 195 OHCA‐cases and 351 950 matched non‐OHCA controls. Epilepsy (cases: 3.58%, controls: 1.60%) was associated with increased rate of OHCA compared with the general population (HR: 1.76, 95%CI: 1.64–1.88) when common OHCA risk factors were taken into account. When we studied antiepileptic drug use, we found that 2 antiepileptic drugs without sodium channel blockage, clonazepam (HR: 1.88, 95%CI: 1.45–2.44) and pregabalin (HR: 1.33, 95%CI: 1.05–1.69), were associated with OHCA, whereas none of the antiepileptic drugs with sodium channel blockage were associated with OHCA.

Conclusion

Epilepsy is associated with increased rate of OHCA. Our findings do not support a possible association between antiepileptic drugs with sodium channel‐blocking properties and OHCA.

Cardiac adverse effects of antiseizure medications

INTRODUCTION

Patients with severe epilepsy are at increased risk of cardiovascular disease and arrhythmias. Although antiseizure medications (ASMs) may have indirect protective effects against cardiovascular events by reducing seizure frequency and hence sudden death in epilepsy, some of them exert cardiotoxic effects.

AREAS COVERED

Patients with epilepsy, mainly those with severe forms, are at higher risk of cardiac disease because their heart can have structural alterations and electrical instability as a consequence of repeated seizures. Some ASMs have direct protective effects through anti-inflammatory, antioxidant, hypotensive, and lipid-reducing properties. Antiseizure medications can also have toxic cardiac effects including both long-term consequences, such as the increased risk of atherogenesis and subsequent cardiovascular disease due to the influence on lipid profile and pro-inflammatory milieu, and immediate effects as the increased risk of potentially fatal arrhythmias due to the influence on ion channels. Sodium channel blocking ASMs may also affect cardiac sodium channels and this effect is particularly observed in subjects with genetic mutations in cardiac ion channels. Fenfluramine cause valvulopathies in obese subjects and this effect need to be evaluated in epilepsy patients.

EXPERT OPINION

For the selection of treatment, cardiotoxic effects of ASMs should be considered; cardiac monitoring of treatment is advisable.

Louis EK, Reichard RR, Edwards WD, Ackerman MJ, Somers VK. Confirmation of Cause of Death Via Comprehensive Autopsy and Whole Exome Molecular Sequencing in People With Epilepsy and Sudden Unexpected Death

Background Sudden cardiac arrest is the leading mode of death in the United States. Epilepsy affects 1% of Americans; yet epidemiological data show a prevalence of 4% in cases of sudden cardiac arrest. Sudden unexpected death in epilepsy (SUDEP) may share features with sudden cardiac arrest. The objective of this study was to report autopsy and genomic findings in a large cohort of SUDEP cases. Methods and Results Mayo Clinic Sudden Death Registry containing cases (ages 0-90 years) of sudden unexpected and unexplained deaths 1960 to present was queried. Exome sequencing performed on decedent cases. From 13 687 cases of sudden death, 656 (4.8%) had a history of seizures, including 368 confirmed by electroencephalography, 96 classified as SUDEP, 58 as non-SUDEP, and 214 as unknown (insufficient records). Mean age of death in SUDEP was 37 (±19.7) years; 56 (58.3%) were male; 65% of deaths occurred at night; 54% were found in bed; and 80.6% were prone. Autopsies were obtained in 83 cases; bystander coronary artery disease was frequently reported as cause of death; nonspecific fibrosis was seen in 32.6% of cases, in structurally normal hearts. There were 4 cases of Dravet syndrome with pathogenic variants in SCN1A gene. Using whole exome sequencing in 11 cases, 18 ultrarare nonsynonymous variants were identified in 6 cases including CACNB2, RYR2, CLNB, CACNA1H, and CLCN2. Conclusions This study examined one of the largest single-center US series of SUDEP cases. Several cases were reclassified as SUDEP, 15% had an ECG when alive, and 11 (11.4%) had blood for whole exome sequencing analysis. The most frequent antemortem genetic finding was pathogenic variants in SCN1A; postmortem whole exome sequencing identified 18 ultrarare variants.

Autonomic manifestations of epilepsy: emerging pathways to sudden death?

Epileptic networks are intimately connected with the autonomic nervous system, as exemplified by a plethora of ictal (during a seizure) autonomic manifestations, including epigastric sensations, palpitations, goosebumps and syncope (fainting). Ictal autonomic changes might serve as diagnostic clues, provide targets for seizure detection and help us to understand the mechanisms that underlie sudden unexpected death in epilepsy (SUDEP). Autonomic alterations are generally more prominent in focal seizures originating from the temporal lobe, demonstrating the importance of limbic structures to the autonomic nervous system, and are particularly pronounced in focal-to-bilateral and generalized tonic-clonic seizures. The presence, type and severity of autonomic features are determined by the seizure onset zone, propagation pathways, lateralization and timing of the seizures, and the presence of interictal autonomic dysfunction. Evidence is mounting that not all autonomic manifestations are linked to SUDEP. In addition, experimental and clinical data emphasize the heterogeneity of SUDEP and its infrequent overlap with sudden cardiac death. Here, we review the spectrum and diagnostic value of the mostly benign and self-limiting autonomic manifestations of epilepsy. In particular, we focus on presentations that are likely to contribute to SUDEP and discuss how wearable devices might help to prevent SUDEP.

Cardiology perspective on seizure-related bradyarrhythmias and SUDEP: A survey study

OBJECTIVE

To determine cardiologist knowledge of and experience with seizure-related bradyarrhythmias and sudden unexpected death in epilepsy (SUDEP).

BACKGROUND

Autonomic changes related to acute seizures are common and can occur during the ictal or postictal period. Two concerning changes in these periods are significant bradycardia and asystole. Postictal asystole has been investigated as a potential mechanism for SUDEP.

METHODS

A 27-question survey delivered to cardiologists and cardiology fellows assessed demographics, personal experience, and training involving SUDEP and seizure-related bradycardia and asystole. Following IRB approval, a list of US cardiology fellowships was constructed using the AAMC public website. Surveys were distributed by email to all programs whose program director or coordinator's email was readily available on their website. They were asked to forward the survey to both cardiology fellows and practicing cardiologists.

RESULTS

Fifty one surveys were completed: 23 from fellows and 28 from practicing cardiologists. Forty nine were from academic centers. Twenty four respondents (47%) reported being consulted for ictal bradycardia or asystole. Nine and 13 recommended treatment for ictal bradycardia or ictal asystole, respectively. Nineteen respondents (37%) reported being consulted for postictal bradycardia or asystole. Eight recommended treatment for postictal bradycardia or asystole, respectively. Treatment recommendations included medical management and/or pacemaker. None reported a substantial knowledge of SUDEP. The most common response interrogating SUDEP awareness (63%) was "no knowledge of SUDEP". Formal SUDEP education was not reported by any participant with only one reporting formal didactics regarding seizure-related arrhythmias.

DISCUSSION

Our results suggest ictal bradyarrhythmias are less commonly known to cardiologists, with SUDEP awareness being far less. Formal education to cardiologists on these two topics could prove beneficial at the intersection of cardiology and care for patients with epilepsy.

Epileptic heart: A clinical syndromic approach

Prevention of premature death in patients with chronic epilepsy remains a major challenge. Multiple pathophysiologic factors have been implicated, with intense investigation of cardiorespiratory mechanisms. Up to four in five patients with chronic epilepsy exhibit cardiovascular comorbidities. These findings led us to propose the concept of an "epileptic heart," defined as "a heart and coronary vasculature damaged by chronic epilepsy as a result of repeated surges in catecholamines and hypoxemia leading to electrical and mechanical dysfunction." Among the most prominent changes documented in the literature are high incidence of myocardial infarction and arrhythmia, altered autonomic tone, diastolic dysfunction, hyperlipidemia, and accelerated atherosclerosis. This suite of pathologic changes prompted us to propose for the first time in this review a syndromic approach for improved clinical detection of the epileptic heart condition. In this review, we discuss the key pathophysiologic mechanisms underlying the candidate criteria along with standard and novel techniques that permit evaluation of each of these factors. Specifically, we present evidence of the utility of standard 12-lead, ambulatory, and multiday patch-based electrocardiograms, along with measures of cardiac electrical instability, including T-wave alternans, heart rate variability to detect altered autonomic tone, echocardiography to detect diastolic dysfunction, and plasma biomarkers for assessing hyperlipidemia and accelerated atherosclerosis. Ultimately, the proposed clinical syndromic approach is intended to improve monitoring and evaluation of cardiac risk in patients with chronic epilepsy to foster improved therapeutic strategies to reduce premature cardiac death.

Cardiorespiratory findings in epilepsy: A recent review on outcomes and pathophysiology

Epilepsy is a debilitating disorder of uncontrollable recurrent seizures that occurs as a result of imbalances in the brain excitatory and inhibitory neuronal signals, that could stem from a range of functional and structural neuronal impairments. Globally, nearly 70 million people are negatively impacted by epilepsy and its comorbidities. One such comorbidity is the effect epilepsy has on the autonomic nervous system (ANS), which plays a role in the control of blood circulation, respiration and gastrointestinal function. These epilepsy-induced impairments in the circulatory and respiratory systems may contribute toward sudden unexpected death in epilepsy (SUDEP). Although, various hypotheses have been proposed regarding the role of epilepsy on ANS, the linking pathological mechanism still remains unclear. Channelopathies and seizure-induced damages in ANS-control brain structures were some of the causal/pathological candidates of cardiorespiratory comorbidities in epilepsy patients, especially in those who were drug resistant. However, emerging preclinical research suggest that neurotransmitter/receptor dysfunction and synaptic changes in the ANS may also contribute to the epilepsy-related autonomic disorders. Thus, pathological mechanisms of cardiorespiratory dysfunction should be elucidated by considering the modifications in anatomy and physiology of the autonomic system caused by seizures. In this regard, we present a comprehensive review of the current literature, both clinical and preclinical animal studies, on the cardiorespiratory findings in epilepsy and elucidate the possible pathological mechanisms of these findings, in hopes to prevent SUDEP especially in patients who are drug resistant.

Loss-of-function variants in Kv 11.1 cardiac channels as a biomarker for SUDEP

Objective

To compare the frequency and impact on the channel function of KCNH2 variants in SUDEP patients with epilepsy controls comprising patients older than 50 years, a group with low SUDEP risk, and establish loss‐of‐function KCNH2 variants as predictive biomarkers of SUDEP risk.

Methods

We searched for KCNH2 variants with a minor allele frequency of <5%. Functional analysis in Xenopus laevis oocytes was performed for all KCNH2 variants identified.

Results

KCNH2 variants were found in 11.1% (10/90) of SUDEP individuals compared to 6.0% (20/332) of epilepsy controls (p = 0.11). Loss‐of‐function KCNH2 variants, defined as causing >20% reduction in maximal amplitude, were observed in 8.9% (8/90) SUDEP patients compared to 3.3% (11/332) epilepsy controls suggesting about threefold enrichment (nominal p = 0.04). KCNH2 variants that did not change channel function occurred at a similar frequency in SUDEP (2.2%; 2/90) and epilepsy control (2.7%; 9/332) cohorts (p > 0.99). Rare KCNH2 variants (<1% allele frequency) associated with greater loss of function and an ~11‐fold enrichment in the SUDEP cohort (nominal p = 0.03). In silico tools were unable to predict the impact of a variant on function highlighting the need for electrophysiological analysis.

Interpretation

These data show that loss‐of‐function KCNH2 variants are enriched in SUDEP patients when compared to an epilepsy population older than 50 years, suggesting that cardiac mechanisms contribute to SUDEP risk. We propose that genetic screening in combination with functional analysis can identify loss‐of‐function KCNH2 variants that could act as biomarkers of an individual’s SUDEP risk.

Electrocardiographic Abnormalities and Mortality in Epilepsy Patients

Background and Objectives: People with epilepsy (PWE) have a 2–3 times higher mortality rate than the general population. Sudden unexpected death in epilepsy (SUDEP) comprises a significant proportion of premature deaths, whereas sudden cardiac death (SCD) is among the leading causes of sudden death in the general population. Cardiac pathologies are significantly more prevalent in PWE. Whether electrocardiographic (ECG) parameters are associated with remote death in PWE has yet to be elucidated. The study objective was to assess whether interictal ECG parameters are associated with mortality in the long-term. Materials and Methods: The study involved 471 epilepsy patients who were hospitalized after a bilateral tonic-clonic seizure(s). ECG parameters were obtained on the day of hospitalization (heart rate, PQ interval, QRS complex, QT interval, heart rate corrected QT interval (QTc), ST segment and T wave changes), as well as reported ECG abnormalities. Mortality data were obtained from the Latvian National Cause-of-Death database 3–11, mean 7.0 years after hospitalization. The association between the ECG parameters and the long-term clinical outcome were examined. Results: At the time of assessment, 75.4% of patients were alive and 24.6% were deceased. Short QTc interval (odds ratio (OR) 4.780; 95% confidence interval (CI) 1.668–13.698; p = 0.004) was associated with a remote death. After the exclusion of known comorbidities with high mortality rates, short QTc (OR 4.631) and ECG signs of left ventricular hypertrophy (OR 5.009) were associated with a remote death. Conclusions: The association between routine 12-lead rest ECG parameters—short QTc interval and a pattern of left ventricular hypertrophy—and remote death in epilepsy patients was found. To the best of our knowledge, this is the first study to associate rest ECG parameters with remote death in an epileptic population.

Proposed Mechanism-Based Risk Stratification and Algorithm to Prevent Sudden Death in Epilepsy

Sudden Unexpected Death in Epilepsy (SUDEP) is the leading cause of death in young adults with uncontrolled seizures. First aid guidance to prevent SUDEP, though, has not been previously published because the rarity of monitored cases has made the underlying mechanism difficult to define. This starkly contrasts with the first aid guidelines for sudden cardiac arrest that have been developed based on retrospective studies and expert consensus and the discussion of resuscitation challenges in various American Heart Association certificate courses. However, an increasing amount of evidence from documented SUDEP cases and near misses and from animal models points to a consistent sequence of events that starts with sudden airway occlusion and suggests a mechanistic basis for enhancing seizure first aid. In monitored cases, this sudden airway occlusion associated with seizure activity can be accurately inferred from inductance plethysmography or (depending on recording bandwidth) from electromyographic (EMG) bursts that are associated with inspiratory attempts appearing on the electroencephalogram (EEG) or the electrocardiogram (ECG). In an emergency setting or outside a hospital, seizure first aid can be improved by (1) keeping a lookout for sudden changes in airway status during a seizure, (2) distinguishing thoracic and abdominal movements during attempts to inspire from effective breathing, (3) applying a simple maneuver, the laryngospasm notch maneuver, that may help with airway management when aggressive airway management is unavailable, (4) providing oxygen early as a preventative step to reduce the risk of death, and (5) performing cardiopulmonary resuscitation before the limited post-ictal window of opportunity closes. We propose that these additions to first aid protocols can limit progression of any potential SUDEP case and prevent death. Risk stratification can be improved by recognition of airway occlusion, attendant hypoxia, and need for resuscitation.

Circadian distribution of autostimulations in rVNS therapy in patients with refractory focal epilepsy

BACKGROUND

Responsive vagus nerve stimulation (rVNS) utilizes an electrocardiograph (ECG)-based algorithm to detect rapid sympathetic activations associated with the onset of a seizure. Abrupt sympathetic activation may also be associated with nocturnal arousals between sleep cycles or transitioning from sleep to wakefulness, a period in which many patients with epilepsy experience seizures. Because of circadian changes in autonomic function, we hypothesized that the autostimulation feature might also behave in a circadian fashion.

OBJECTIVE

The aim of this study was to assess the circadian rhythmicity of autostimulations in rVNS treatment in patients with drug-resistant epilepsy (DRE).

MATERIALS AND METHODS

We performed a retrospective follow-up study of 30 patients with DRE treated with rVNS including 17 new implantations and 13 battery replacements at a single center in Finland. After initiation of autostimulation mode, the exact rVNS stimulation parameters and the timestamps of all individual autostimulations delivered were registered. A clustered autostimulation was defined as any autostimulation that occurred within the duration of the therapeutic cycle during the therapy "OFF" time compared with both the previous autostimulation and the following autostimulation.

RESULTS

Autostimulations and especially autostimulation clusters show a higher probability of occurring in the morning and less at night. This trend appeared to follow the circadian rhythm of cortisol concentration.

CONCLUSIONS

Early morning peaks of autostimulations at low thresholds may reflect awakening-induced activation of the cardiovascular system, which is associated with a shift towards the dominance of the sympathetic branch of the autonomic nervous system. Cortisol release occurs in parallel driven by wakening-induced activation of the hypothalamic-pituitary-adrenal axis, which is fine-tuned by direct sympathetic input to the adrenal gland. This is of interest considering the known sympathetic hyperactivity in patients with epilepsy.

Inherited cardiac arrhythmias

The main inherited cardiac arrhythmias are long QT syndrome, short QT syndrome, catecholaminergic polymorphic ventricular tachycardia and Brugada syndrome. These rare diseases are often the underlying cause of sudden cardiac death in young individuals and result from mutations in several genes encoding ion channels or proteins involved in their regulation. The genetic defects lead to alterations in the ionic currents that determine the morphology and duration of the cardiac action potential, and individuals with these disorders often present with syncope or a life-threatening arrhythmic episode. The diagnosis is based on clinical presentation and history, the characteristics of the electrocardiographic recording at rest and during exercise and genetic analyses. Management relies on pharmacological therapy, mostly β-adrenergic receptor blockers (specifically, propranolol and nadolol) and sodium and transient outward current blockers (such as quinidine), or surgical interventions, including left cardiac sympathetic denervation and implantation of a cardioverter-defibrillator. All these arrhythmias are potentially life-threatening and have substantial negative effects on the quality of life of patients. Future research should focus on the identification of genes associated with the diseases and other risk factors, improved risk stratification and, in particular for Brugada syndrome, effective therapies.

The Epileptic Heart: Concept and clinical evidence

Sudden unexpected death in epilepsy (SUDEP) is generally considered to result from a seizure, typically convulsive and usually but not always occurring during sleep, followed by a sequence of events in the postictal period starting with respiratory distress and progressing to eventual cardiac asystole and death. Yet, recent community-based studies indicate a 3-fold greater incidence of sudden cardiac death in patients with chronic epilepsy than in the general population, and that in 66% of cases, the cardiac arrest occurred during routine daily activity and without a temporal relationship with a typical seizure. To distinguish a primarily cardiac cause of death in patients with epilepsy from the above description of SUDEP, we propose the concept of the "Epileptic Heart" as "a heart and coronary vasculature damaged by chronic epilepsy as a result of repeated surges in catecholamines and hypoxemia leading to electrical and mechanical dysfunction." This review starts with an overview of the pathophysiological and other lines of evidence supporting the biological plausibility of the Epileptic Heart, followed by a description of tools that have been used to generate new electrocardiogram (EKG)-derived data in patients with epilepsy that strongly support the Epileptic Heart concept and its propensity to cause sudden cardiac death in patients with epilepsy independent of an immediately preceding seizure.

Cardiac arrhythmias in Dravet syndrome: an observational multicenter study

Objectives

We ascertained the prevalence of ictal arrhythmias to explain the high rate of sudden unexpected death in epilepsy (SUDEP) in Dravet syndrome (DS).

Methods

We selected cases with clinical DS, ≥6 years, SCN1A mutation, and ≥1 seizure/week. Home‐based ECG recordings were performed for 20 days continuously. Cases were matched for age and sex to two epilepsy controls with no DS and ≥1 major motor seizure during video‐EEG. We determined the prevalence of peri‐ictal asystole, bradycardia, QTc changes, and effects of convulsive seizures (CS) on heart rate, heart rate variability (HRV), and PR/QRS. Generalized estimating equations were used to account for multiple seizures within subjects, seizure type, and sleep/wakefulness.

Results

We included 59 cases. Ictal recordings were obtained in 45 cases and compared to 90 controls. We analyzed 547 seizures in DS (300 CS) and 169 in controls (120 CS). No asystole occurred. Postictal bradycardia was more common in controls (n = 11, 6.5%) than cases (n = 4, 0.7%; P = 0.002). Peri‐ictal QTc‐lengthening (≥60ms) occurred more frequently in DS (n = 64, 12%) than controls (n = 8, 4.7%, P = 0.048); pathologically prolonged QTc was rare (once in each group). In DS, interictal HRV was lower compared to controls (RMSSD P = 0.029); peri‐ictal values did not differ between the groups. Prolonged QRS/PR was rare and more common in controls (QRS: one vs. none; PR: three vs. one).

Interpretation

We did not identify major arrhythmias in DS which can directly explain high SUDEP rates. Peri‐ictal QTc‐lengthening was, however, more common in DS. This may reflect unstable repolarization and an increased propensity for arrhythmias.

Neuro-arrhythmology: a challenging field of action and research: a review from the Task Force of Neuro-arrhythmology of Italian Association of Arrhythmias and Cardiac Pacing

: There is a growing interest in the study of the mechanisms of heart and brain interactions with the aim to improve the management of high-impact cardiac rhythm disorders, first of all atrial fibrillation. However, there are several topics to which the scientific interests of cardiologists and neurologists converge constituting the basis for enhancing the development of neuro-arrhythmology. This multidisciplinary field should cover a wide spectrum of diseases, even beyond the classical framework corresponding to stroke and atrial fibrillation and include the complex issues of seizures as well as loss of consciousness and syncope. The implications of a more focused interaction between neurologists and cardiologists in the field of neuro-arrhythmology should include in perspective the institution of research networks specifically devoted to investigate 'from bench to bedside' the complex pathophysiological links of the abovementioned diseases, with involvement of scientists in the field of biochemistry, genetics, molecular medicine, physiology, pathology and bioengineering. An investment in the field could have important implications in the perspectives of a more personalized approach to patients and diseases, in the context of 'precision'medicine. Large datasets and electronic medical records, with the approach typical of 'big data' could enhance the possibility of new findings with potentially important clinical implications. Finally, the interaction between neurologists and cardiologists involved in arrythmia management should have some organizational implications, with new models of healthcare delivery based on multidisciplinary assistance, similarly to that applied in the case of syncope units.

Cardiac electrical instability in newly diagnosed/chronic epilepsy tracked by Holter and ECG patch

OBJECTIVE

We hypothesized that cardiac electrical instability and abnormal autonomic tone result from cumulative cardiac injury sustained in recurrent seizures. We tested this hypothesis by comparing T-wave alternans (TWA) and heart rate variability (HRV), both established markers of sudden cardiac death (SCD) risk, in patients with chronic as compared to newly diagnosed epilepsy.

METHODS

In this prospective, observational cohort study, patients (newly diagnosed epilepsy, n = 6, age 41.8 ± 6.8 years; chronic epilepsy, n = 6, age 40.2 ± 5.6 years [p = 0.85]) were monitored either with Holter recorder alone or simultaneously with 14-day Zio XT extended continuous ECG patch monitor. TWA was assessed by Food and Drug Administration-cleared Modified Moving Average analysis; HRV was calculated by rMSSD.

RESULTS

TWA levels in chronic epilepsy were significantly higher than in newly diagnosed epilepsy (62 ± 5.4 vs 35 ± 1.3 μV, p < 0.002); the latter did not differ from healthy control adults. In all patients with chronic epilepsy, TWA exceeded the established ≥47-μV TWA cutpoint and rMSSD HRV was inversely related to TWA levels. Patients with chronic epilepsy exhibited elevated TWA levels equivalently on Holter and ECG patch recordings (p = 0.38) with a high correlation (r ² = 0.99, p < 0.01) across 24 hours.

CONCLUSION

Based on the limited number of patients studied, it appears that chronic epilepsy, the common use of sodium channel antagonists, or other factors are associated with higher TWA levels and simultaneously with lower rMSSD HRV, which is suggestive of autonomic dysfunction or higher sympathetic tone. The ECG patch monitor used has equivalent accuracy to Holter monitoring for TWA and HRV and permits longer-term ECG sampling.

The yield of long-term electrocardiographic recordings in refractory focal epilepsy

OBJECTIVE

To determine the incidence of clinically relevant arrhythmias in refractory focal epilepsy and to assess the potential of postictal arrhythmias as risk markers for sudden unexpected death in epilepsy (SUDEP).

METHODS

We recruited people with refractory focal epilepsy without signs of ictal asystole and who had at least one focal seizure per month and implanted a loop recorder with 2-year follow-up. The devices automatically record arrhythmias. Subjects and caregivers were instructed to make additional peri-ictal recordings. Clinically relevant arrhythmias were defined as asystole ≥ 6 seconds; atrial fibrillation < 55 beats per minute (bpm), or > 200 bpm and duration > 30 seconds; persistent sinus bradycardia < 40 bpm while awake; and second- or third-degree atrioventricular block and ventricular tachycardia/fibrillation. We performed 12-lead electrocardiography (ECG) and tilt table testing to identify non-seizure-related causes of asystole.

RESULTS

We included 49 people and accumulated 1060 months of monitoring. A total of 16 474 seizures were reported, of which 4679 were captured on ECG. No clinically relevant arrhythmias were identified. Three people had a total of 18 short-lasting (<6 seconds) periods of asystole, resulting in an incidence of 2.91 events per 1000 patient-months. None of these coincided with a reported seizure; one was explained by micturition syncope. Other non-clinically relevant arrhythmias included paroxysmal atrial fibrillation (n = 2), supraventricular tachycardia (n = 1), and sinus tachycardia with a right bundle branch block configuration (n = 1).

SIGNIFICANCE

We found no clinically relevant arrhythmias in people with refractory focal epilepsy during long-term follow-up. The absence of postictal arrhythmias does not support the use of loop recorders in people at high SUDEP risk.

Acquired cardiac channelopathies in epilepsy: Evidence, mechanisms, and clinical significance

There is growing evidence that cardiac dysfunction in patients with chronic epilepsy could play a pathogenic role in sudden unexpected death in epilepsy (SUDEP). Recent animal studies have revealed that epilepsy secondarily alters the expression of cardiac ion channels alongside abnormal cardiac electrophysiology and remodeling. These molecular findings represent novel evidence for an acquired cardiac channelopathy in epilepsy, distinct from inherited ion channels mutations associated with cardiocerebral phenotypes. Specifically, seizure activity has been shown to alter the messenger RNA (mRNA) and protein expression of voltage-gated sodium channels (Na_v 1.1, Na_v 1.5), voltage-gated potassium channels (K_v 4.2, K_v 4.3), sodium-calcium exchangers (NCX1), and nonspecific cation-conducting channels (HCN2, HCN4). The pathophysiology may involve autonomic dysfunction and structural cardiac disease, as both are independently associated with epilepsy and ion channel dysregulation. Indeed, in vivo and in vitro studies of cardiac pathology reveal a complex network of signaling pathways and transcription factors regulating ion channel expression in the setting of sympathetic overactivity, cardiac failure, and hypertrophy. Other mechanisms such as circulating inflammatory mediators or exogenous effects of antiepileptic medications lack evidence. Moreover, an acquired cardiac channelopathy may underlie the electrophysiologic cardiac abnormalities seen in chronic epilepsy, potentially contributing to the increased risk of malignant arrhythmias and sudden death. Therefore, further investigation is necessary to establish whether cardiac ion channel dysregulation similarly occurs in patients with epilepsy, and to characterize any pathogenic relationship with SUDEP.

Abnormal repolarization: A common electrocardiographic finding in patients with epilepsy

BACKGROUND

Recently, certain forms of early repolarization (ER) on electrocardiograms (ECGs) have been considered a possible marker of increased sudden cardiac death risk. The frequency, characteristics, and clinical follow-up with which these forms of ER are present in epilepsy patients, and whether or not abnormal ER contributes to sudden unexplained death in epilepsy patients (SUDEP) is unknown.

METHODS AND RESULTS

The amplitude of J peak and ST-segment morphology after ER on 12-lead ECGs were assessed in 354 epilepsy patients (age, 33 ± 16 years; 54% men) and 140 age- and sex-matched control subjects (age, 31 ± 12 years; 50% men). Abnormal ER prevalence (J-wave amplitude ≥0.1 mV) was greater in epilepsy patients (19.8%) compared with controls (8.6%; P = 0.002) in inferior ECG leads but not in lateral leads ( P = 0.40). ER with a horizontal or descending ST segment was also more prevalent in epilepsy patients ( P < 0.001). After introducing antiepileptic drugs in 36 epilepsy patients, there were no significant ER changes. Similarly, in 64 epilepsy patients with seizure suppression, ER comparison before and after seizure control revealed no significant changes. Male gender was the only significant predictor of abnormal ER in epilepsy patients ( P = 0.03). During a median follow-up of 7 years, SUDEP occurred in two patients, one with abnormal ER.

CONCLUSIONS

Abnormal ER may be more prevalent in epilepsy patients than in controls and is not altered by antiepileptic drugs or achievement of epilepsy suppression. The relation of abnormal ER to SUDEP remains in need of further study.

Mitochondrial damage in hippocampal neurons of rats with epileptic protein expression of Fas and caspase-3

Epilepsy model in rats was established to observe the behavior and pathological changes, and to detect mitochondrial dysfunction, exploring its possible molecular mechanisms. The epileptic status of Sprague-Dawley (SD) rats was induced by intraperitoneal injection of lithium chloride, and the change of behavior was recorded. Electroencephalogram (EEG) was used to measure the abnormal discharge of neurons in rats. The brain tissue was fixed with polyformaldehyde and the paraffin sections were prepared, and the damage of the hippocampal neurons was observed with Nissl staining. Mitochondrial ATP and mitochondrial DNA were examined to assess mitochondrial dysfunction. Finally, qPCR and western blot analysis were used to detect mRNA and protein expression of fatty acid synthetase (Fas), Fas ligand (FasL) and caspase-3 in rat hippocampal neurons. The correlation between the mitochondrial dysfunction of rat hippocampal neurons and Fas and caspase-3 was analyzed. Compared with the normal group rats, the model group showed typical seizures, which were determined by the Racine attack score. EEG of the hippocampus of the model group was recorded in cluster in model group rats. Nissl staining showed a different degree of damage to the hippocampal neurons in the model group compared with normal rats. The mitochondrial ATP content and DNA content of rat hippocampal neurons in the model group were significantly lower than that of normal rats (P<0.01). The qPCR and western blot results showed that the mRNA and protein expression levels of Fas, FasL and caspase-3 were significantly increased in the hippocampus of rat model group (P<0.01). The expression level of Fas and caspase-3 in hippocampal tissues of rats was negatively correlated with mitochondrial DNA content. In conclusion, seizures cause damage of neuron mitochondria in rat hippocampus leading to death of hippocampal neurons, the mitochondrial damage of hippocampal neurons in epileptic rats was closely related to the expression of Fas and caspase-3.

An explanation for sudden death in epilepsy (SUDEP)

This review traces the examination of autonomic, cardiovascular, and respiratory derangements associated with seizure activity in the clinical and preclinical literature generally, and in the author's animal model specifically, and concludes with the author's views on the potential mechanisms for sudden death in epilepsy (SUDEP). An animal model that employs kainic acid-induced seizures on a background of urethane anesthesia has permitted unprecedented access to the behavior of autonomic, cardiovascular, and respiratory systems during seizure activity. The result is a detailed description of the major causes of death and how this animal model can be used to develop and test preventative and interventional strategies. A critical translational step was taken when the rat data were shown to directly parallel data from definite SUDEP cases in the clinical literature. The reasons why ventricular fibrillation as a cause of death is so rarely reported and tools for verifying that seizure-associated laryngospasm can induce obstructive apnea as a cause of death are discussed in detail. Many details of the specific kinetics of activation of brainstem neurons serving autonomic and respiratory function remain to be elucidated, but the boundary conditions described in this review provide an excellent framework for more focused studies. A number of studies conducted in animal models of seizure activity and in epilepsy patients have contributed information on the autonomic, cardiovascular, and respiratory consequences of seizure activity spreading through hypothalamus and brainstem to the periphery. The result is detailed information on the systemic impact of seizure spread and the development of an understanding of the essential mechanistic features of sudden unexpected death in epilepsy (SUDEP). This review summarizes translation of data obtained from animal models to biomarkers that are useful in evaluating data from epilepsy patients.

Interictal cardiac repolarization abnormalities in people with epilepsy

BACKGROUND AND OBJECTIVE

The occurrence of cardiac electrical abnormalities such as repolarization disorders in patients with epilepsy was previously documented and may, in part, clarify the mechanism of sudden unexpected death in those patients. The aim of this study was to investigate the frequency of cardiac repolarization disorders among patients with epilepsy and whether specific demographic- or disease-related features were associated with their occurrence.

SUBJECTS AND METHODS

This cross-sectional study was carried out on 1000 subjects with epilepsy who were compared with age- and sex-matched 2500 subjects without epilepsy. Clinical assessment, which included careful history taking and examination, was carried out for all participants in addition to resting 12-lead electrocardiogram (ECG) recording. Electrocardiograms were reviewed by experienced cardiologists. Electrocardiogram intervals were measured, and morphological abnormalities were identified using standard guidelines.

RESULTS

Repolarization abnormalities were found in 142 (14.2%) patients with epilepsy. A statistically significant elevation in percentage of corrected QT interval (QTc) prolongation (both severe and borderline) among patients with epilepsy compared with controls was documented (8.4% vs 2%, P<0.001). Epilepsy increased the likelihood of hosting prolonged QTc more than 4 times (95% confidence interval: 3.175-6.515; odds ratio: 4.548; P<0.001). Affected patients were significantly older (95% confidence interval: 1.012-1.044; odds ratio: 1.027; P=0.001), and the abnormality was significantly more prevalent among those with poor seizure control (95% confidence interval: 1.103-2.966; odds ratio: 1.809; P=0.019). On the other hand, early repolarization (ER) pattern and Brugada type ECG pattern (BP) were significantly more prevalent in subjects without epilepsy.

CONCLUSIONS

Corrected QT interval prolongation (both severe and borderline) was more prevalent among patients with epilepsy, especially if uncontrolled or elderly. Electrocardiogram should be established as a part of the diagnostic workup of epilepsy in order to identify such electrocardiographic abnormality.

Simultaneous Video-EEG-ECG Monitoring to Identify Neurocardiac Dysfunction in Mouse Models of Epilepsy

In epilepsy, seizures can evoke cardiac rhythm disturbances such as heart rate changes, conduction blocks, asystoles, and arrhythmias, which can potentially increase risk of sudden unexpected death in epilepsy (SUDEP). Electroencephalography (EEG) and electrocardiography (ECG) are widely used clinical diagnostic tools to monitor for abnormal brain and cardiac rhythms in patients. Here, a technique to simultaneously record video, EEG, and ECG in mice to measure behavior, brain, and cardiac activities, respectively, is described. The technique described herein utilizes a tethered (i.e., wired) recording configuration in which the implanted electrode on the head of the mouse is hard-wired to the recording equipment. Compared to wireless telemetry recording systems, the tethered arrangement possesses several technical advantages such as a greater possible number of channels for recording EEG or other biopotentials; lower electrode costs; and greater frequency bandwidth (i.e., sampling rate) of recordings. The basics of this technique can also be easily modified to accommodate recording other biosignals, such as electromyography (EMG) or plethysmography for assessment of muscle and respiratory activity, respectively. In addition to describing how to perform the EEG-ECG recordings, we also detail methods to quantify the resulting data for seizures, EEG spectral power, cardiac function, and heart rate variability, which we demonstrate in an example experiment using a mouse with epilepsy due to Kcna1 gene deletion. Video-EEG-ECG monitoring in mouse models of epilepsy or other neurological disease provides a powerful tool to identify dysfunction at the level of the brain, heart, or brain-heart interactions.

Serotonin reuptake inhibitors and mortality in epilepsy: A linked primary-care cohort study

OBJECTIVE

Preliminary evidence suggests that serotonin reuptake inhibitor (SRI) use may increase postictal respiratory drive and prevent death. We sought to determine whether SRIs are associated with improved all-cause and possible seizure-specific mortality in patients with epilepsy.

METHODS

Patients with epilepsy and a random 10:1 sample without epilepsy were extracted from The ClinicAl research using LInked Bespoke studies and Electronic health Records (CALIBER) resource. The hazard ratio (HR) of all-cause and possible seizure-specific mortality, treating SRI use as a time-varying covariate, was determined using the date of a second SRI prescription as exposure and in discrete 6-month periods over the entire duration of follow-up. We used Cox regression and competing risk models with Firth correction to calculate the HR. We controlled for age, sex, depression, comorbidity, (Charlson comorbidity index) and socioeconomic status (Index of Multiple Deprivation).

RESULTS

We identified 2,718,952 eligible patients in CALIBER, of whom 16,379 (0.60%) had epilepsy. Median age and follow-up were 44 (interquartile range [IQR] 29-61]) and 6.4 years (IQR 2.4-10.4 years), respectively, and 53% were female. A total of 2,178 patients (13%) had at least two SRI prescriptions. Hazard of all-cause mortality was significantly elevated following a second prescription for an SRI (HR 1.64 95% confidence interval [95% CI] 1.44-1.86; p < 0.001). The HR was similar in 163,778 age, sex, and general practitioner (GP) practice-matched controls without epilepsy. Exposure to an SRI was not associated with seizure-related death (HR 1.08, 95% CI 0.59-1.97; 0.796).

SIGNIFICANCE

There is no evidence in this large population-based cohort that SRIs protect against all-cause mortality or seizure-specific mortality. Rather, SRI use was associated with increased mortality, irrespective of epilepsy, which is probably due to various factors associated with the use of antidepressants. Larger studies with systematically collected clinical data are needed to shed further light on these findings.

Signal Detection of Imipenem Compared to Other Drugs from Korea Adverse Event Reporting System Database

PURPOSE

To detect signals of adverse drug events after imipenem treatment using the Korea Institute of Drug Safety & Risk Management-Korea adverse event reporting system database (KIDS-KD).

MATERIALS AND METHODS

We performed data mining using KIDS-KD, which was constructed using spontaneously reported adverse event (AE) reports between December 1988 and June 2014. We detected signals calculated the proportional reporting ratio, reporting odds ratio, and information component of imipenem. We defined a signal as any AE that satisfied all three indices. The signals were compared with drug labels of nine countries.

RESULTS

There were 807582 spontaneous AEs reports in the KIDS-KD. Among those, the number of antibiotics related AEs was 192510; 3382 reports were associated with imipenem. The most common imipenem-associated AE was the drug eruption; 353 times. We calculated the signal by comparing with all other antibiotics and drugs; 58 and 53 signals satisfied the three methods. We compared the drug labelling information of nine countries, including the USA, the UK, Japan, Italy, Switzerland, Germany, France, Canada, and South Korea, and discovered that the following signals were currently not included in drug labels: hypokalemia, cardiac arrest, cardiac failure, Parkinson's syndrome, myocardial infarction, and prostate enlargement. Hypokalemia was an additional signal compared with all other antibiotics, and the other signals were not different compared with all other antibiotics and all other drugs.

CONCLUSION

We detected new signals that were not listed on the drug labels of nine countries. However, further pharmacoepidemiologic research is needed to evaluate the causality of these signals.

Antiepileptic Drugs Impair Shortening of Isolated Cardiomyocytes

Background

Most antiepileptic drugs (AEDs) inhibit seizure generation by acting on voltage-dependent ion channels. Voltage-dependent sodium and calcium channels are commonly expressed in brain and heart, suggesting that AEDs may have considerable cardiodepressive effects, thereby facilitating sudden cardiac death as a potential cause of sudden unexpected death in epilepsy. Here, we investigated the effects of carbamazepine (CBZ), lamotrigine (LTG), and levetiracetam (LEV) alone and in combination on the shortening properties of isolated ventricular cardiomyocytes of wild-type mice.

Methods

Properties of murine cardiomyocytes were determined by recording the sarcomere shortening with a video imaging system before, during, and after administration of AEDs in different concentrations and combinations. We assessed (i) the number of successful shortenings during continuous electrical stimulation (electromechanical coupling) and (ii) the shortening amplitude as well as other shortening-related properties upon repetitive electrical stimulation at 4 Hz. Data are given as mean ± SEM.

Results

At 100 μM, CBZ (10 cells), LTG (11 cells), and LEV (11 cells) alone had no effect on the electromechanical coupling but reversibly reduced shortening amplitudes by 15 ± 4, 24 ± 3, and 11 ± 3%, respectively. Increasing the LTG concentration to 250 (21 cells) and 500 μM (4 cells) reversibly inhibited the electromechanical coupling in 62 and 100% of the experiments. Importantly, simultaneous application of CBZ, LTG, and LEV at 100 μM also impaired the electromechanical coupling in 8 of 19 cardiomyocytes (42%) and reduced the shortening amplitude by 21 ± 4%.

Conclusion

Our data show that AEDs reversibly impair cardiac excitation and contraction. Importantly, the blocking effect on electromechanical coupling appears to be additive when different AEDs are simultaneously applied. The translational value of these experimental findings into clinical practice is limited. Our results, however, suggest that rationale AED therapy may be important with respect to cardiac side effects and potential facilitation of serious cardiac dysfunction especially when AEDs are used in combination or at very high doses.

Summary of the 2016 Partners Against Mortality in Epilepsy (PAME) Conference

Authors: Kevin D Graber, MD, Jeffrey Buchhalter, MD, PhD, Elson So, MD, Rainer Surges, MD, Detlev Boison, PhD, Franck Kalume, PhD, Cyndi Wright, Brian Gehlbach, MD, Jeff Noebels, MD, PhD, Vicky Whittemore, PhD, Elizabeth J. Donner, MD, MSc, Tom Stanton, MPP, Henry Smithson, MD, Jane Hanna, Masud Seyal, MD, PhD, Philippe Ryvlin, MD, PhD The third biannual Partners Against Mortality in Epilepsy (PAME) conference was held in Alexandria, VA from June 23-26, 2016. This was an intimate meeting of clinical and basic scientists, clinicians, people affected by Sudden Unexpected Death in Epilepsy Patients (SUDEP) in a loved one, people living with epilepsy and patient advocate organizations. Plenary sessions have been summarized by moderators, including: 1) Mortality in people with epilepsy: epidemiology and surveillance. 2) Mortality in children. 3) What do we know about the factors that predispose certain people to die from a seizure? 4) What are the events that occur during and after a seizure that cause a death in SUDEP? 5) What are the options for prevention now and in the future? 6) Advocacy perspectives: how can we speed up awareness and prevention? 7) Updates and discussion on select programs in mortality research. Breakout sessions allowed for a more focused audience. Those summarized here are: Frequent non-SUDEP causes of mortality in people with epilepsy; Mechanisms of SUDEP; Lessons learned in grief and how to better support families; Future directions for research to impact prevention; and How do we improve SUDEP risk disclosure? While significant progress has been made with review of human mortality in epilepsy and study of animal models, this meeting emphasized the need for: better understandings of the epidemiology of SUDEP, advances in the understandings of mechanisms, continued search for biomarkers and preventative measures, patient education, increased awareness, continued advocacy for patient and family support and research funding.

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.

The pathophysiology of cardiac dysfunction in epilepsy

Alterations in cardiac electrophysiology are an established consequence of long-standing drug resistant epilepsy. Patients with chronic epilepsy display abnormalities in both sinoatrial node pacemaker current as well as ventricular repolarizing current that places them at a greater risk of developing life-threatening cardiac arrhythmias. The development of cardiac arrhythmias secondary to drug resistant epilepsy is believed to be a key mechanism underlying the phenomenon of Sudden Unexpected Death in EPilepsy (SUDEP). Though an increasing amount of studies examining both animal models and human patients have provided evidence that chronic epilepsy can detrimentally affect cardiac function, the underlying pathophysiology remains unclear. Recent work has shown the expression of several key cardiac ion channels to be altered in animal models of genetic and acquired epilepsies. This has led to the currently held paradigm that cardiac ion channel expression may be secondarily altered as a consequence of seizure activity-resulting in electrophysiological cardiac dysfunction. Furthermore, cortical autonomic dysfunction - resulting from seizure activity-has also been suggested to play a role, whereby seizure activity may indirectly influence cardiac function via altering centrally-mediated autonomic output to the heart. In this review, we discuss various cardiac dysrhythmias associated with seizure events-including tachycardia, bradycardia and QT prolongation, both ictally and inter-ictally, as well as the role of the autonomic nervous system. We further discuss key ion channels expressed in both the heart and the brain that have been shown to be altered in epilepsy and may be responsible for the development of cardiac dysrhythmias secondary to chronic epilepsy.

Leaky RyR2 channels unleash a brainstem spreading depolarization mechanism of sudden cardiac death

Cardiorespiratory failure is the most common cause of sudden unexplained death in epilepsy (SUDEP). Genetic autopsies have detected "leaky" gain-of-function mutations in the ryanodine receptor-2 (RyR2) gene in both SUDEP and sudden cardiac death cases linked to catecholaminergic polymorphic ventricular tachycardia that feature lethal cardiac arrhythmias without structural abnormality. Here we find that a human leaky RyR2 mutation, R176Q (RQ), alters neurotransmitter release probability in mice and significantly lowers the threshold for spreading depolarization (SD) in dorsal medulla, leading to cardiorespiratory collapse. Rare episodes of sinus bradycardia, spontaneous seizure, and sudden death were detected in RQ/+ mutant mice in vivo; however, when provoked, cortical seizures frequently led to apneas, brainstem SD, cardiorespiratory failure, and death. In vitro studies revealed that the RQ mutation selectively strengthened excitatory, but not inhibitory, synapses and facilitated SD in both the neocortex as well as brainstem dorsal medulla autonomic microcircuits. These data link defects in neuronal intracellular calcium homeostasis to the vulnerability of central autonomic brainstem pathways to hypoxic stress and implicate brainstem SD as a previously unrecognized site and mechanism contributing to premature death in individuals with leaky RYR2 mutations.

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.

Who to target in sudden unexpected death in epilepsy prevention and how? Risk factors, biomarkers, and intervention study designs

The risk of dying suddenly and unexpectedly is increased 24- to 28-fold among young people with epilepsy compared to the general population, but the incidence of sudden unexpected death in epilepsy (SUDEP) varies markedly depending on the epilepsy population. This article first reviews risk factors and biomarkers for SUDEP with the overall aim of enabling identification of epilepsy populations with different risk levels as a background for a discussion of possible intervention strategies. The by far most important clinical risk factor is frequency of generalized tonic-clonic seizures (GTCS), but nocturnal seizures, early age at onset, and long duration of epilepsy have been identified as additional risk factors. Lack of antiepileptic drug (AED) treatment or, in the context of clinical trials, adjunctive placebo versus active treatment is associated with increased risks. Despite considerable research, reliable electrophysiologic (electrocardiography [ECG] or electroencephalography [EEG]) biomarkers of SUDEP risk remain to be established. This is an important limitation for prevention strategies and intervention studies. There is a lack of biomarkers for SUDEP, and until validated biomarkers are found, the endpoint of interventions to prevent SUDEP must be SUDEP itself. These interventions, be they pharmacologic, seizure-detection devices, or nocturnal supervision, require large numbers. Possible methods for assessing prevention measures include public health community interventions, self-management, and more traditional (and much more expensive) randomized clinical trials.

Cardiac arrhythmias during or after epileptic seizures

Seizure-related cardiac arrhythmias are frequently reported and have been implicated as potential pathomechanisms of Sudden Unexpected Death in Epilepsy (SUDEP). We attempted to identify clinical profiles associated with various (post)ictal cardiac arrhythmias. We conducted a systematic search from the first date available to July 2013 on the combination of two terms: 'cardiac arrhythmias' and 'epilepsy'. The databases searched were PubMed, Embase (OVID version), Web of Science and COCHRANE Library. We attempted to identify all case reports and case series. We identified seven distinct patterns of (post)ictal cardiac arrhythmias: ictal asystole (103 cases), postictal asystole (13 cases), ictal bradycardia (25 cases), ictal atrioventricular (AV)-conduction block (11 cases), postictal AV-conduction block (2 cases), (post)ictal atrial flutter/atrial fibrillation (14 cases) and postictal ventricular fibrillation (3 cases). Ictal asystole had a mean prevalence of 0.318% (95% CI 0.316% to 0.320%) in people with refractory epilepsy who underwent video-EEG monitoring. Ictal asystole, bradycardia and AV-conduction block were self-limiting in all but one of the cases and seen during focal dyscognitive seizures. Seizure onset was mostly temporal (91%) without consistent lateralisation. Postictal arrhythmias were mostly found following convulsive seizures and often associated with (near) SUDEP. The contrasting clinical profiles of ictal and postictal arrhythmias suggest different pathomechanisms. Postictal rather than ictal arrhythmias seem of greater importance to the pathophysiology of SUDEP.

Sudden cardiac arrest in people with epilepsy in the community: Circumstances and risk factors

OBJECTIVE

To ascertain whether characteristics of ventricular tachycardia/fibrillation (VT/VF) differed between people with epilepsy and those without and which individuals with epilepsy were at highest risk.

METHODS

We ascertained 18 people with active epilepsy identified in a community-based registry of sudden cardiac arrest (SCA) with ECG-confirmed VT/VF (cases). We compared them with 470 individuals with VT/VF without epilepsy (VT/VF controls) and 54 individuals with epilepsy without VT/VF (epilepsy controls). Data on comorbidity, epilepsy severity, and medication use were collected and entered into (conditional) logistic regression models to identify determinants of VT/VF in epilepsy.

RESULTS

In most cases, there was an obvious (10/18) or presumed cardiovascular cause (5/18) in view of preexisting heart disease. In 2 of the 3 remaining events, near-sudden unexpected death in epilepsy (SUDEP) was established after successful resuscitation. Cases had a higher prevalence of congenital/inherited heart disease (17% vs 1%, p = 0.002), and experienced VT/VF at younger age (57 vs 64 years, p = 0.023) than VT/VF controls. VT/VF in cases occurred more frequently at/near home (89% vs 58%, p = 0.009), and was less frequently witnessed (72% vs 89%, p = 0.048) than in VT/VF controls. Cases more frequently had clinically relevant heart disease (50% vs 15%, p = 0.005) and intellectual disability (28% vs 1%, p < 0.001) than epilepsy controls.

CONCLUSION

Cardiovascular disease rather than epilepsy characteristics is the main determinant of VT/VF in people with epilepsy in the community. SCA and SUDEP are partially overlapping disease entities.

Seizure Frequencies and Number of Anti-epileptic Drugs as Risk Factors for Sudden Unexpected Death in Epilepsy

The purpose of this study was to investigate the association between clinical variables and sudden unexpected death in epilepsy (SUDEP) and identify risk factors for SUDEP. SUDEP is one of the most frequent causes of death in patients with epilepsy. Previous studies have reported possible risk factors associated with SUDEP, but there need to be elucidated yet. The cases were 26 patients with SUDEP and three control patients were included for each case, matched for age, sex, and date of initial clinical visit. All demographic and clinical characteristics, including age, sex, disease duration, classification of epilepsy, age at seizure onset, kind and number of antiepileptic drugs, were compared between cases and controls. Seizure frequency was higher in SUDEP cases than in controls (P=0.035). Univariate analysis using conditional logistic regression showed that higher seizure frequency (odds ratio [OR]=3.1, P=0.021) and the number of antiepileptic drugs (AEDs) (OR=2.0, P=0.009) were significantly associated with SUDEP. Only the number of AEDs remained significant in multivariate analysis (OR=1.8, P=0.026). Frequent seizures and multi-drug therapy were associated with SUDEP. This may suggest that the severity of epilepsy is associated with SUDEP, regardless of the type of AED used.

Increased prevalence of ECG markers for sudden cardiac arrest in refractory epilepsy

BACKGROUND AND AIM

People with epilepsy are at increased risk of sudden cardiac arrest (SCA) due to ECG-confirmed ventricular tachycardia/fibrillation, as seen in a community-based study. We aimed to determine whether ECG-risk markers of SCA are more prevalent in people with epilepsy.

METHODS

In a cross-sectional, retrospective study, we analysed the ECG recordings of 185 people with refractory epilepsy and 178 controls without epilepsy. Data on epilepsy characteristics, cardiac comorbidity, and drug use were collected, and general ECG variables (heart rate (HR), PQ and QRS intervals) assessed. We analysed ECGs for three markers of SCA risk: severe QTc prolongation (male >450 ms, female >470 ms), Brugada ECG pattern, and early repolarisation pattern (ERP). Multivariate regression models were used to analyse differences between groups, and to identify associated clinical and epilepsy-related characteristics.

RESULTS

People with epilepsy had higher HR (71 vs 62 bpm, p<0.001) and a longer PQ interval (162.8 vs 152.6 ms, p=0.001). Severe QTc prolongation and ERP were more prevalent in people with epilepsy (QTc prolongation: 5% vs 0%; p=0.002; ERP: 34% vs 13%, p<0.001), while the Brugada ECG pattern was equally frequent in both groups (2% vs 1%, p>0.999). After adjustment for covariates, epilepsy remained associated with ERP (ORadj 2.4, 95% CI 1.1 to 5.5) and severe QTc prolongation (ORadj 9.9, 95% CI 1.1 to 1317.7).

CONCLUSIONS

ERP and severe QTc prolongation appear to be more prevalent in people with refractory epilepsy. Future studies must determine whether this contributes to increased SCA risk in people with epilepsy.

Factors Affecting the Occurrence of Out-of-Hospital Sudden Cardiac Arrest

Objective. This paper aims to discover the risk factors for sudden cardiac arrest (out-of-hospital sudden cardiac arrest (OHSCA)) which significantly affect the decision about prioritizing emergency interventions before dispatching medical emergency teams, risk of deterioration of the patient's condition at the scene, and emergency procedures. Methods. A retrospective study taking into account the international classification of diseases ICD-10 based on an analysis of medical records of Emergency Medical Service in Wroclaw (Poland). Results. The main risk factor of OHSCA is coexistence of external cause leading to illness or death (ICD Group V-10) as well as the occurrence of diseases from the group of endocrine disorders (group E), in particular diabetes. The increase in the risk of OHSCA incidence is affected by nervous system diseases (group G), especially epilepsy of various etiologies, respiratory diseases (group J), mainly COPD, and bronchial asthma or mental and behavioral disorders (group F), with particular emphasis on the drugs issue. The procedure for receiving calls for Emergency Notification Centre does not take into account clinical risk factors for sudden cardiac arrest (SCA). Conclusion. Having knowledge of OHSCA risk factors can increase the efficiency of rescue operations from rapid assessment and provision of appropriate medical team, through effective performance of medical emergency treatment and prevention of SCA or finally reducing the costs.