The safety of flecainide treatment of atrial fibrillation: long-term incidence of sudden cardiac death and proarrhythmic events

Propafenone use in coronary artery disease patients undergoing atrial fibrillation ablation

BACKGROUND

Antiarrhythmic drugs (AADs) are frequently used after atrial fibrillation (AF) ablation. Class IC AAD use after AF ablation in patients with coronary artery disease (CAD) is uncertain. The aim was to evaluate propafenone use in CAD patients undergoing AF ablation and to compare propafenone with amiodarone regarding ventricular arrhythmia and mortality.

METHODS

In this retrospective, longitudinal cohort study, consecutive patients with mild to moderate CAD, undergoing AF ablation and receiving either propafenone (study group, n = 263) or amiodarone (control group, n = 499) in the blanking period, were included. After propensity score matching, 212 patients in each group were compared for the primary outcome defined as a composite of ventricular arrhythmic events, which included sudden cardiac death, sustained ventricular tachycardia or fibrillation, or non-sustained ventricular tachycardia (NSVT). Cardiovascular and non-cardiovascular mortality were evaluated as secondary outcomes.

RESULTS

Baseline variables of the study and control groups were well matched after propensity score matching. At 12-month follow up, 20 patients (4.7%) (11 in propafenone group and 9 in amiodarone group) experienced the primary outcome measure of NSVT (Gray test p = 0.645). No sustained ventricular tachycardia, ventricular fibrillation, sudden cardiac death, or cardiovascular mortality were observed. On multivariable competing analysis, age and diabetes but not propafenone use (hazard ratio 1.017; p = 0.804) were found to be independent and significant predictors of the primary outcome measure.

CONCLUSION

Propafenone use after AF ablation in patients with mild to moderate CAD had a safety profile similar to amiodarone and was not associated with major arrhythmic events.

Guideline-Concordant Antiarrhythmic Drug Use in the Get With The Guidelines-Atrial Fibrillation Registry

BACKGROUND

Antiarrhythmic drug (AAD) therapy for atrial fibrillation (AF) can be associated with both proarrhythmic and noncardiovascular toxicities. Practice guidelines recommend tailored AAD therapy for AF based on patient-specific characteristics, such as coronary artery disease and heart failure, to minimize adverse events. However, current prescription patterns for specific AADs and the degree to which these guidelines are followed in practice are unknown.

METHODS

Patients enrolled in the Get With The Guidelines-Atrial Fibrillation registry with a primary diagnosis of AF discharged on an AAD between January 2014 and November 2018 were included. We analyzed rates of prescription of each AAD in several subgroups including those without structural heart disease. We classified AAD use as guideline concordant or nonguideline concordant based on 6 criteria derived from the American Heart Association/American College of Cardiology/Heart Rhythm Society AF guidelines. Guideline concordance for amiodarone was not considered applicable, since its use is not specifically contraindicated in the guidelines for reasons such as structural heart disease or renal function. We analyzed guideline-concordant AAD use by specific patient and hospital characteristics, and regional and temporal trends.

RESULTS

Among 21 921 patients from 123 sites, the median age was 69 years, 46% female and 51% had paroxysmal AF. The most commonly prescribed AAD was amiodarone (38%). Sotalol (23.2%) and dofetilide (19.2%) were each more commonly prescribed than either flecainide (9.8%) or propafenone (4.8%). Overall guideline-concordant AAD prescription at discharge was 84%. Guideline-concordant AAD use by drug was as follows: dofetilide 93%, sotalol 66%, flecainide 68%, propafenone 48%, and dronedarone 80%. There was variability in rate of guideline-concordant AAD use by hospital and geographic region.

CONCLUSIONS

Amiodarone remains the most commonly prescribed AAD for AF followed by sotalol and dofetilide. Rates of guideline-concordant AAD use were high, and there was significant variability by specific drugs, hospitals, and regions, highlighting opportunities for additional quality improvement.

Predicting cardiac electrical response to sodium-channel blockade and Brugada syndrome using polygenic risk scores

Aims

Sodium-channel blockers (SCBs) are associated with arrhythmia, but variability of cardiac electrical response remains unexplained. We sought to identify predictors of ajmaline-induced PR and QRS changes and Type I Brugada syndrome (BrS) electrocardiogram (ECG).

Methods and results

In 1368 patients that underwent ajmaline infusion for suspected BrS, we performed measurements of 26 721 ECGs, dose–response mixed modelling and genotyping. We calculated polygenic risk scores (PRS) for PR interval (PRS_PR), QRS duration (PRS_QRS), and Brugada syndrome (PRS_BrS) derived from published genome-wide association studies and used regression analysis to identify predictors of ajmaline dose related PR change (slope) and QRS slope. We derived and validated using bootstrapping a predictive model for ajmaline-induced Type I BrS ECG. Higher PRS_PR, baseline PR, and female sex are associated with more pronounced PR slope, while PRS_QRS and age are positively associated with QRS slope (P < 0.01 for all). PRS_BrS, baseline QRS duration, presence of Type II or III BrS ECG at baseline, and family history of BrS are independently associated with the occurrence of a Type I BrS ECG, with good predictive accuracy (optimism-corrected C-statistic 0.74).

Conclusion

We show for the first time that genetic factors underlie the variability of cardiac electrical response to SCB. PRS_BrS, family history, and a baseline ECG can predict the development of a diagnostic drug-induced Type I BrS ECG with clinically relevant accuracy. These findings could lead to the use of PRS in the diagnosis of BrS and, if confirmed in population studies, to identify patients at risk for toxicity when given SCB.

Dominant rule of community effect in synchronized beating behavior of cardiomyocyte networks

Exploiting the combination of latest microfabrication technologies and single cell measurement technologies, we can measure the interactions of single cells, and cell networks from "algebraic" and "geometric" perspectives under the full control of their environments and interactions. However, the experimental constructive single cell-based approach still remains the limitations regarding the quality and condition control of those cells. To overcome these limitations, mathematical modeling is one of the most powerful complementary approaches. In this review, we first explain our on-chip experimental methods for constructive approach, and we introduce the results of the "community effect" of beating cardiomyocyte networks as an example of this approach. On-chip analysis revealed that (1) synchronized interbeat intervals (IBIs) of cell networks were followed to the more stable beating cells even their IBIs were slower than the other cells, which is against the conventional faster firing regulation or "overdrive suppression," and (2) fluctuation of IBIs of cardiomyocyte networks decreased according to the increase of the number of connected cells regardless of their geometry. The mathematical simulation of this synchronous behavior of cardiomyocyte networks also fitted well with the experimental results after incorporating the fluctuation-dissipation theorem into the oscillating stochastic phase model, in which the concept of spatially arranged cardiomyocyte networks was involved. The constructive experiments and mathematical modeling indicated the dominant rule of synchronization behavior of beating cardiomyocyte networks is a kind of stability-oriented synchronization phenomenon as the "community effect" or a fluctuation-dissipation phenomenon. Finally, as a practical application of this approach, the predictive cardiotoxicity is introduced.

Flecainide: Electrophysiological properties, clinical indications, and practical aspects

Over the last 35 years, flecainide proved itself one of the most commonly used arrhythmic drugs, expanding its original indication for ventricular arrhythmias and results nowadays as the cornerstone of the rhythm control strategy in atrial fibrillation management of patients without structural heart disease. While the increased mortality associated with flecainide in the Cardiac Arrhythmia Suppression Trial (CAST) still casts his shadow over flecainide clinical profile, this compound has subsequently demonstrated safe and is now used successfully for a plethora of indications, including pharmacological cardioversion of atrial fibrillation, cathecolaminergic polymorphic ventricular tachycardia, supraventricular tachyarrhythmias and ventricular pre-excitation. Moreover, the recent marketing of a controlled release formulation, along with the intravenous and immediate release formulations, increased the armamentarium to the clinician's disposal while improving patients' compliance. In the present paper, we offer a comprehensive review of the anti-arrhythmic effects of flecainide, detailing its electrophysiological properties, its effects on the conduction system, its clinical use and the major side effects and contraindications in clinical practice.

On-chip spatiotemporal electrophysiological analysis of human stem cell derived cardiomyocytes enables quantitative assessment of proarrhythmia in drug development

We examined a simultaneous combined spatiotemporal field potential duration (FPD) and cell-to-cell conduction time (CT) in lined-up shaped human embryonic stem cell-derived cardiomyocytes (hESC-CMs) using an on-chip multielectrode array (MEA) system to evaluate two origins of lethal arrhythmia, repolarization and depolarization. The repolarization index, FPD, was prolonged by E-4031 and astemizole, and shortened by verapamil, flecainide and terfenadine at 10 times higher than therapeutic plasma concentrations of each drug, but it did not change after lidocaine treatment up to 100 μM. CT was increased by astemizol, flecainide, terfenadine, and lidocaine at equivalent concentrations of Nav1.5 IC50, suggesting that CT may be an index of cardiac depolarization because the increase in CT (i.e., decrease in cell-to-cell conduction speed) was relevant to Nav1.5 inhibition. Fluctuations (short-term variability; STV) of FPD and CT, STVFPD and STVCT also discriminated between torsadogenic and non-torsadogenic compounds with significant increases in their fluctuation values, enabling precise prediction of arrhythmogenic risk as potential new indices.

Drug-induced life-threatening arrhythmias and sudden cardiac death: A clinical perspective of long QT, short QT and Brugada syndromes

Sudden cardiac death is a major public health challenge, which can be caused by genetic or acquired structural or electrophysiological abnormalities. These abnormalities include hereditary channelopathies: long QT, short QT and Brugada syndromes. These syndromes are a notable concern, particularly in young people, due to their high propensity for severe ventricular arrhythmias and sudden cardiac death. Current evidence suggests the involvement of an increasing number of drugs in acquired forms of long QT and Brugada syndromes. However, drug-induced short QT syndrome is still a rarely reported condition. Therefore, there has been speculation on its clinical significance, since few fatal arrhythmias and sudden cardiac death cases have been described so far. Drug-induced proarrhythmia is a growing challenge for physicians, regulatory agencies and the pharmaceutical industry. Physicians should weigh the risks of potentially fatal outcomes against the therapeutic benefits, when making decisions about drug prescriptions. Growing concerns about its safety and the need for more accurate predictive models for drug-induced fatal outcomes justify further research in these fields. The aim of this article is to comprehensively and critically review the recently published evidence with regard to drug-induced life-threatening arrhythmias and sudden cardiac death. This article will take into account the provision of data to physicians that are useful in the identification of the culprit drugs, and thus, contribute to the prompt recognition and management of these serious clinical conditions.

Role of abnormal repolarization in the mechanism of cardiac arrhythmia

In cardiac patients, life-threatening tachyarrhythmia is often precipitated by abnormal changes in ventricular repolarization and refractoriness. Repolarization abnormalities typically evolve as a consequence of impaired function of outward K⁺ currents in cardiac myocytes, which may be caused by genetic defects or result from various acquired pathophysiological conditions, including electrical remodelling in cardiac disease, ion channel modulation by clinically used pharmacological agents, and systemic electrolyte disorders seen in heart failure, such as hypokalaemia. Cardiac electrical instability attributed to abnormal repolarization relies on the complex interplay between a provocative arrhythmic trigger and vulnerable arrhythmic substrate, with a central role played by the excessive prolongation of ventricular action potential duration, impaired intracellular Ca²⁺ handling, and slowed impulse conduction. This review outlines the electrical activity of ventricular myocytes in normal conditions and cardiac disease, describes classical electrophysiological mechanisms of cardiac arrhythmia, and provides an update on repolarization-related surrogates currently used to assess arrhythmic propensity, including spatial dispersion of repolarization, activation-repolarization coupling, electrical restitution, TRIaD (triangulation, reverse use dependence, instability, and dispersion), and the electromechanical window. This is followed by a discussion of the mechanisms that account for the dependence of arrhythmic vulnerability on the location of the ventricular pacing site. Finally, the review clarifies the electrophysiological basis for cardiac arrhythmia produced by hypokalaemia, and gives insight into the clinical importance and pathophysiology of drug-induced arrhythmia, with particular focus on class Ia (quinidine, procainamide) and Ic (flecainide) Na⁺ channel blockers, and class III antiarrhythmic agents that block the delayed rectifier K⁺ channel (dofetilide).

The evolving landscape of oral anti-arrhythmic prescriptions for atrial fibrillation in England: 1998-2014

AIMS

An important decision in the management of patients with atrial fibrillation is whether to adopt a rate or rhythm control strategy. Options for the latter include oral membrane-active anti-arrhythmic drugs (AADs) or catheter ablation. Recent prescription trends may have been affected by the introduction of dronedarone and an increasing number of reports suggesting increased mortality in those taking AADs. We describe the trend in oral AAD prescriptions in England in the period 1998-2014.

METHODS AND RESULTS

We conducted a retrospective study using data from the Prescription Cost Analysis system, which holds information on every prescription dispensed in the community in England. We obtained data from 1998 to October 2014 for all Class Ia, Ic, and III AADs. Amiodarone and sotalol remain the most commonly prescribed AADs in England, though the use of both is decreasing. There has been a linear increase in the uptake of flecainide. Dronedarone prescriptions peaked in 2011, and our most recent data show that amiodarone prescriptions are 25-fold those of dronedarone.

CONCLUSION

There is a decline in the use of amiodarone and sotalol consistent with the growing safety concerns with these drugs along with neutral results from landmark trials comparing rate and rhythm control. Dronedarone has failed to make an impact on AAD prescribing. In contrast, flecainide has seen an increase in use during the study period.

Utility of Routine Exercise Testing to Detect Rate-Related QRS Widening in Patients Without Structural Heart Disease on Class Ic Antiarrhythmic Agents (Flecainide and Propafenone)

Class Ic antiarrhythmic agents are effective in the treatment of various atrial tachyarrhythmias. They are known to cause rate-related QRS widening in the presence of structural heart disease, which can lead to life-threatening arrhythmias. The role of routine exercise electrocardiography in patients without structural heart disease is unknown. All patients initiated on class Ic antiarrhythmic agents and who had exercise electrocardiography performed from June 2009 to June 2013 were included. Symptom-limited treadmill electrocardiography was performed to detect significant QRS widening at peak exercise (defined as an increase of >25% of baseline QRS). Fifty-six patients were included in the study. All patients were screened for structural heart disease before initiation of the medication. Significant QRS widening and atrial tachycardia occurred in a single patient, which terminated with cessation of exercise. This patient had a history of tachycardia-mediated cardiomyopathy with normalization of ejection fraction 3 years before being placed on flecainide. In conclusion, routine exercise testing to detect QRS widening is not warranted in patients with no structural heart disease.

Narrow therapeutic index drugs: a clinical pharmacological consideration to flecainide

Purpose

The therapeutic index (TI) is the range of doses at which a medication is effective without unacceptable adverse events. Drugs with a narrow TI (NTIDs) have a narrow window between their effective doses and those at which they produce adverse toxic effects. Generic drugs may be substituted for brand-name drugs provided that they meet the recommended bioequivalence (BE) limits. However, an appropriate range of BE for NTIDs is essential to define due to the potential for ineffectiveness or adverse events. Flecainide is an antiarrhythmic agent that has the potential to be considered an NTID. This review aims to evaluate the literature surrounding guidelines on generic substitution for NTIDs and to evaluate the evidence for flecainide to be considered an NTID.

Methods

A review of recommendations from various regulatory authorities regarding BE and NTIDs, and publications regarding the NTID characteristics of flecainide, was carried out.

Results

Regulatory authorities generally recommend reduced BE limits for NTIDs. Some, but not all, regulatory authorities specify flecainide as an NTID. The literature review demonstrated that flecainide displays NTID characteristics including a steep drug dose–response relationship for safety and efficacy, a need for therapeutic drug monitoring of pharmacokinetic (PK) or pharmacodynamics measures and intra-subject variability in its PK properties.

Conclusions

There is much evidence for flecainide to be considered an NTID based on both preclinical and clinical data. A clear understanding of the potential of proarrhythmic effects or lack of efficacy, careful patient selection and regular monitoring are essential for the safe and rational administration of flecainide.

Electronic supplementary material

The online version of this article (doi:10.1007/s00228-015-1832-0) contains supplementary material, which is available to authorized users.

Sudden death of a horse with supraventricular tachycardia following oral administration of flecainide acetate

OBJECTIVE

To describe a case of supraventricular tachycardia and sudden death in a horse following administration of flecainide acetate.

CASE SUMMARY

An 8-year-old Hanoverian warmblood gelding was treated for chronic, naturally occurring, supraventricular tachycardia with digoxin, procainamide hydrochloride, quinidine sulfate, and flecainide acetate. After oral administration of flecainide, polymorphic ventricular tachycardia (torsades de pointes) and ventricular fibrillation developed, leading to cardiovascular collapse and death.

NEW OR UNIQUE INFORMATION PROVIDED

Atrial fibrillation is the most commonly diagnosed dysrhythmia associated with poor performance in horses, while atrial tachycardia is rarely documented. Here, we describe a case of sudden death in a horse with atrial tachycardia following the oral administration of flecainide acetate, after the lack of response to other antiarrhythmic drugs. Information provided in this case report is new and will make clinicians aware of the potential complications of flecainide alone or in combination with other drugs, in horses with cardiac dysrhythmias.

The efficacy and tolerability of commonly used agents to prevent recurrence of atrial fibrillation after successful cardioversion

A number of therapeutic strategies exist for the restoration and maintenance of sinus rhythm in patients presenting with atrial fibrillation. The acute success rate with electrical cardioversion is high. However, many patients relapse into atrial fibrillation. A major challenge faced by those who care for patients with atrial fibrillation is the long-term maintenance of sinus rhythm whilst avoiding treatment-related adverse effects. This review examines the efficacy and tolerability of conventional anti-arrhythmic drugs for the secondary prevention of atrial fibrillation in the post-cardioversion period.

Cytochrome P450-2D6 Genotype Definition May Improve Therapy for Paroxysmal Atrial Fibrillation A Case of Syncope Following "Pill-in-the-Pocket" Quinidine plus Propafenone

Classes 1A, 1C and III anti-arrhythmics may be ineffective or induce adverse events including potentially fatal arrhythmias when administered in recommended doses. Serum levels of these medications vary widely during conventional dosing due in large part to variations in cytochrome P450-2D6 isoenzyme activity which metabolizes most antiarrhythmics in addition to over 25% of other commonly prescribed medications. 2D6 activity is also profoundly inhibited by some antiarrhythmics and other commonly used medications and varies widely between the individuals of all populations, a pattern which has resulted in separation of subjects into 4 phenotypes and genotypes consisting of poor metabolizers (PM), intermediate metabolizers (IM), efficient metabolizers (EM), and ultra-rapid metabolizers (UM). Patients with a phenotype PM classification almost universally are also genotype PM due to the possession of two inactive 2D6 alleles, with this PM pattern often inducing supratherapeutic and toxic antiarrhythmic blood levels during conventional antiarrhythmic therapy. UM individuals have supranormal levels of 2D6 activity often created by the presence of 3 or more active alleles which often induce subtherapeutic and ineffective drug levels during antiarrhythmic administration in conventional doses. We searched for evidence relating Cytochrome P450-2D6 phenotypes or genotypes to antiarrhythmic metabolism in order to judge whether this analysis might contribute to improved safety and effectiveness of antiarrhythmic medications commonly utilized in the treatment of atrial fibrillation. The available evidence strongly supported these possibilities. We also describe a patient in whom knowledge of his IM/PM CYP2D6 genotype might have prevented the only episode of syncope and myocardial stunning which developed during his 28 years of "Pill-in-a-Pocket" therapy.

CYP2D6 genotype affects age-related decline in flecainide clearance: a population pharmacokinetic analysis

OBJECTIVE

To investigate the association between age-related decline in flecainide clearance and CYP2D6 genotype, we conducted a population pharmacokinetic analysis of flecainide using routine therapeutic drug monitoring data.

METHODS

Population pharmacokinetic analysis was performed on retrospective data from 163 genotyped patients treated with oral flecainide for supraventricular tachyarrhythmias. The CYP2D6 genotype was categorized as CYP2D6 homozygous extensive metabolizers (hom-EMs; n=57), heterozygous extensive metabolizers (het-EMs; n=79), and intermediate metabolizers and poor metabolizers (IMs/PMs; n=27).

RESULTS

Population pharmacokinetic analysis revealed that estimated glomerular filtration rate, body weight, female sex, and aging were important factors for estimating flecainide clearance. The metabolic clearance was decreased age dependently in a curvilinear fashion, where the lower clearance was observed in greater than 60 years for het-EMs and greater than 55 years for IMs/PMs. The reduction in metabolic clearance in elderly (70 years) patients compared with middle-aged (52 years) patients was different among the CYP2D6 genotype groups: 22.1 and 49.5% in CYP2D6 het-EMs and IMs/PMs, respectively, and no change in hom-EMs. A 11.4% reduction in estimated glomerular filtration rate in elderly patients compared with middle-aged patients corresponded to 6.1% decline in flecainide clearance. Overall, the age-related decline in flecainide clearance was 6.1% in hom-EMs, 16.3% in het-EMs, and 28.9% in IMs/PMs groups.

CONCLUSION

This study suggests that CYP2D6 genotype is a determinant factor of age-related decline in flecainide clearance.

Safety of flecainide

Flecainide is a class Ic antiarrhythmic agent that has an important role as part of rhythm control strategies in patients with atrial fibrillation (AF). Early clinical data on the use of flecainide showed an increase in arrhythmias and mortality compared with placebo in patients with a previous myocardial infarction and asymptomatic or mildly symptomatic ventricular arrhythmias. These findings only apply to a specific group of patients with left ventricular dysfunction and ischaemic heart disease, but had a negative impact on the use of class Ic antiarrhythmics across all indications and patient groups. The aim of this review was to evaluate the available safety data for flecainide in the literature and to assess its current use in patients with AF. Current European guidelines now recommend the use of flecainide in carefully selected groups of patients with AF who do not have structural heart disease. This includes for the cardioversion of recent-onset AF, pretreatment prior to direct current cardioversion, out-of-hospital acute oral therapy ('pill-in-the-pocket' approach) and for the ongoing maintenance of sinus rhythm. Potential cardiac adverse effects of flecainide include proarrhythmia, conduction abnormalities and negative inotropic effects. Dizziness is the most frequent non-cardiac side effect, followed by blurred vision and difficulty focusing; these are almost all mild, transient and tolerable. Data from recent clinical trials in patients with supraventricular arrhythmias suggest that flecainide has a good tolerability profile in groups of appropriately selected patients. Caution is required when using flecainide in patients with renal dysfunction, and there are a number of drug interactions, but these are well documented and manageable. Overall, flecainide is a good choice for the pharmacological management of AF. It has a good safety record and low incidence of adverse effects, rare end-organ toxicity and a low risk of ventricular proarrhythmia. To ensure that the benefits of treatment outweigh any potential risks, careful patient selection and monitoring is required.