Safety of flecainide

[Antiarrhythmic drugs in the present day]

Cardiac arrhythmias cause a significant proportion of hospitalizations and physician contacts worldwide. By using antiarrhythmic drugs, cardiac arrhythmias can be effectively treated and the frequency of recurrences reduced. Atrial fibrillation and heart failure represent diseases in which antiarrhythmic drugs are more often used on a long-term basis. The aim of this article is to provide an overview of the most common antiarrhythmic drugs and their uses as well as to provide recommendations for adequate handling and use, especially in the outpatient setting. In addition to long-term use, some antiarrhythmic drugs are also administered for the acute management of supraventricular or ventricular tachycardia. Relevant contraindications, side effects and interactions must be considered, meaning that patients should be followed up when using these potent drugs. This article shows in detail what to consider when using antiarrhythmic drugs in order to ensure not only effective but also safe treatment.

Gut microbiota and cardiac arrhythmia: a pharmacokinetic scope

BACKGROUND

Dealing with cardiac arrhythmia is a difficult challenge. Choosing between different anti-arrhythmic drugs (AADs) while being cautious about the pro-arrhythmic characteristics of some of these drugs and their diverse interaction with other drugs is a real obstacle.

MAIN BODY

Gut microbiota (GM), in our bodies, are now being considered as a hidden organ which can regulate our immune system, digest complex food, and secrete bioactive compounds. Yet, GM are encountered in the pathophysiology of arrhythmia and can affect the pharmacokinetics of AADs, as well as some anti-thrombotics, resulting in altering their bioavailability, therapeutic function and may predispose to some of their unpleasant adverse effects.

CONCLUSIONS

Knowledge of the exact role of GM in the pharmacokinetics of these drugs is now essential for better understanding of the art of arrhythmia management. Also, it will help deciding when to consider probiotics as an adjunctive therapy while treating arrhythmia. This should be discovered in the near future.

A Possible Mechanism for Flecainide Induced Dizziness

OBJECTIVE

Flecainide is an oral class IC antiarrhythmic drug whose most common extracardiac adverse reactions are "dizziness" and "visual disturbances." We describe a case of flecainide associated- bilateral vestibulopathy and a literature review of this drug's effect on the vestibular system.

PATIENT

Sixty-nine-year-old man with a 3-month history of unsteadiness and dizziness after an increase in the dose of flecainide.

INTERVENTIONS

Otologic examination, video head-impulse test, vestibular evoked myogenic potentials, pure tone audiometry and high-resolution magnetic resonance imaging.

RESULTS

Otologic examination, including the head-impulse test, and vestibular testing revealed bilateral vestibulopathy.

CONCLUSIONS

Dizziness is a common extracardiac adverse reaction of Flecainide. Based on the clinical case that we present and the literature review carried out, we hypothesized that a possible mechanism by which flecainide might cause dizziness and visual disturbances is bilateral vestibulopathy.

Increased atrial effectiveness of flecainide conferred by altered biophysical properties of sodium channels

Atrial fibrillation (AF) affects over 1% of the population and is a leading cause of stroke and heart failure in the elderly. A feared side effect of sodium channel blocker therapy, ventricular pro-arrhythmia, appears to be relatively rare in patients with AF. The biophysical reasons for this relative safety of sodium blockers are not known. Our data demonstrates intrinsic differences between atrial and ventricular cardiac voltage-gated sodium currents (INa), leading to reduced maximum upstroke velocity of action potential and slower conduction, in left atria compared to ventricle. Reduced atrial INa is only detected at physiological membrane potentials and is driven by alterations in sodium channel biophysical properties and not by NaV1.5 protein expression. Flecainide displayed greater inhibition of atrial INa, greater reduction of maximum upstroke velocity of action potential, and slowed conduction in atrial cells and tissue. Our work highlights differences in biophysical properties of sodium channels in left atria and ventricles and their response to flecainide. These differences can explain the relative safety of sodium channel blocker therapy in patients with atrial fibrillation.

Flecainide in Ventricular Arrhythmias: From Old Myths to New Perspectives

Flecainide is an IC antiarrhythmic drug (AAD) that received in 1984 Food and Drug Administration approval for the treatment of sustained ventricular tachycardia (VT) and subsequently for rhythm control of atrial fibrillation (AF). Currently, flecainide is mainly employed for sinus rhythm maintenance in AF and the treatment of idiopathic ventricular arrhythmias (IVA) in absence of ischaemic and structural heart disease on the basis of CAST data. Recent studies enrolling patients with different structural heart diseases demonstrated good effectiveness and safety profile of flecainide. The purpose of this review is to assess current evidence for appropriate and safe use of flecainide, 30 years after CAST data, in the light of new diagnostic and therapeutic tools in the field of ischaemic and non-ischaemic heart disease.

Flecainide-induced AV dyssynchrony and atrial latency progression in a patient with a dual-chamber pacemaker

INTRODUCTION

Flecainide is a class 1C antiarrhythmic primarily usedfor the management of supraventricular arrhythmias. Adverse effects in patientswith pacemakers are poorly described in the current literature. We report acase of worsening intracardiac conduction in a patient with baseline atriallatency.

CASE

A patient with paroxysmalatrial fibrillation and recently implanted dual chamber pacemaker withresultant atrial latency underwent flecainide treatment resulting in worseningatrial latency, progressive dyspnea, and pacemaker syndrome physiology. The patientexperienced symptomatic improvement with pacemaker reprogramming to AAI andreduced flecainide dosages.

CONCLUSION

Prudence should be exercised when initiating flecainide therapy, particularly in pacemaker-dependentpatients, who may be at risk for increasedthresholds, inconsistent capture, and latency. In the setting of apparentcapture latency, changing to AAI mode may both confirm the diagnosis andprovide a symptomatic benefit.

Flecainide-induced myalgias and weakness: a rare adverse reaction

Flecainide is a class 1C antiarrhythmic, which is known to cause several cardiac and non-cardiac adverse reactions. We report a case of a 62-year-old woman with atrial fibrillation who presented with generalised myalgias and intermittent chest heaviness after being started on flecainide. She had undergone her third cardiac ablation 1 week prior to presentation and was subsequently started on flecainide 150 mg two times per day. On physical examination, she had diminished reflexes and diffuse calf tenderness. Her blood tests demonstrated an increased erythrocyte sedimentation rate and C reactive protein, but otherwise normal infectious and autoimmune labs. Her ECG showed normal sinus rhythm. A Naranjo score of 7 suggested flecainide as a probable cause of her myalgias. The patient's symptoms started to normalise within 24 hours of discontinuation of flecainide. Our case highlights that myalgias are a potential rare adverse effect that should be considered in patients prescribed flecainide.

Neurological complications of cardiovascular drugs

Cardiovascular drugs are used to treat arterial hypertension, hyperlipidemia, arrhythmias, heart failure, and coronary artery disease. They also include antiplatelet and anticoagulant drugs that are essential for prevention of cardiogenic embolism. Most neurologic complications of the cardiovascular drugs are minor or transient and are far outweighed by the anticipated benefits of treatment. Other neurologic complications are more serious and require early recognition and management. Overtreatment of arterial hypertension may cause lightheadedness or fatigue but often responds readily to dose adjustment or an alternative drug. Other drug complications may be more troublesome as in myalgia associated with statins or headache associated with vasodilators. The recognized bleeding risk of the antithrombotics requires careful calculation of risk/benefit ratios for individual patients. Many neurologic complications of cardiovascular drugs are well documented in clinical trials with known frequency and severity, but others are rare and recognized only in isolated case reports or small case series. This chapter draws on both sources to report the adverse effects on muscle, nerve, and brain associated with commonly used cardiovascular drugs.

Atrial Fibrillation in COVID-19: From Epidemiological Association to Pharmacological Implications

Coronavirus disease 2019 (COVID-19) outbreak is a public health emergency of international concerns because of a highly pathogenic human coronavirus (HCoV), actually named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Despite much emerging data about the epidemiological association between cardiovascular diseases and COVID-19, little is still known about atrial fibrillation and its optimal management in this clinical contest. The aim of our review is to describe the pharmacological interactions between cardiovascular drugs more commonly used in atrial fibrillation management and experimental COVID-19 therapies, based on EU and US summaries of product characteristics.

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.

Anti-arrhythmic therapy in athletes

The spectrum of arrhythmias that may be encountered in athletes ranges from isolated ectopic beats to ventricular tachycardia, usually in the context of a structurally normal heart. Anti-arrhythmic therapy in these individuals may be particularly challenging because of the young age, the hypervagotonic state, the desire to maintain a high physical performance, the reluctance to take medications and the need to avoid molecules included in the list of prohibited drugs of the World Anti-Doping Agency. Furthermore, the possible serious adverse effects of anti-arrhythmic drugs should be balanced against the benign nature of arrhythmias in patients with no underlying heart disease. The review summarizes the most common arrhythmias of athletes and the possible therapeutic options, including anti-arrhythmic drugs and non-pharmacological interventions. Eligibility criteria according to current guidelines are also addressed.

Selective late sodium current inhibitor GS-458967 suppresses Torsades de Pointes by mostly affecting perpetuation but not initiation of the arrhythmia

Background and Purpose

Enhanced late sodium current (late I_Na) in heart failure and long QT syndrome type 3 is proarrhythmic. This study investigated the antiarrhythmic effect and mode of action of the selective and potent late I_Na inhibitor GS‐458967 (GS967) against Torsades de Pointes arrhythmias (TdP) in the chronic atrioventricular block (CAVB) dog.

Experimental Approach

Electrophysiological and antiarrhythmic effects of GS967 were evaluated in isolated canine ventricular cardiomyocytes and CAVB dogs with dofetilide‐induced early afterdepolarizations (EADs) and TdP, respectively. Mapping of intramural cardiac electrical activity in vivo was conducted to study effects of GS967 on spatial dispersion of repolarization.

Key Results

GS967 (IC₅₀~200nM) significantly shortened repolarization in canine ventricular cardiomyocytes and sinus rhythm (SR) dogs, in a concentration and dose‐dependent manner. In vitro, despite addition of 1μM GS967, dofetilide‐induced EADs remained present in 42% and 35% of cardiomyocytes from SR and CAVB dogs, respectively. Nonetheless, GS967 (787±265nM) completely abolished dofetilide‐induced TdP in CAVB dogs (10/14 after dofetilide to 0/14 dogs after GS967), while single ectopic beats (sEB) persisted in 9 animals. In vivo mapping experiments showed that GS967 significantly reduced spatial dispersion of repolarization: cubic dispersion was significantly decreased from 237±54ms after dofetilide to 123±34ms after GS967.

Conclusion and Implications

GS967 terminated all dofetilide‐induced TdP without completely suppressing EADs and sEB in vitro and in vivo, respectively. The antiarrhythmic mode of action of GS967, through the reduction of spatial dispersion of repolarization, seems to predominantly impede the perpetuation of arrhythmic events into TdP rather than their initiating trigger.

β1-Adrenergic receptor Arg389Gly polymorphism affects the antiarrhythmic efficacy of flecainide in patients with coadministration of β-blockers

OBJECTIVE

β1-Adrenergic receptor (β1-AR) stimulation modulates the antiarrhythmic activities of sodium channel blockers. The β1-AR Gly389 variant shows a marked decrease in agonist-stimulated cyclic AMP production compared with that of the wild-type Arg389 in vitro. We investigated whether the Arg389Gly polymorphism affects the efficacy of flecainide, a typical sodium channel blocker, in patients with or without coadministration of β-blockers.

METHODS

The effects of the β1-AR Arg389Gly polymorphism on the antiarrhythmic efficacy of flecainide were compared between with and without coadministered β-blockers in 159 patients with supraventricular tachyarrhythmia. The antiarrhythmic efficacy of flecainide was assessed for at least 2 months by evaluating symptomatology, 12-lead ECGs, and Holter monitoring results.

RESULTS

Genetic differences in the antiarrhythmic efficacy of flecainide were observed in patients with coadministration of β-blockers. Tachyarrhythmia was well controlled in 60% of Arg389-homozygotes, 30% of Gly389-heterozygotes, and 0% of Gly389-homozygotes (P=0.001). In contrast, no difference in the antiarrhythmic efficacy was observed among the three genotypes in the patients without coadministration of β-blockers (64, 70, and 60%, respectively). Heart rate in tachyarrhythmia in patients treated with flecainide was significantly higher in Gly389 carriers than in Arg389-homozygotes (P=0.013).

CONCLUSION

The Gly389 polymorphism decreased the antiarrhythmic efficacy of flecainide when coadministered with β-blockers. The results indicate that the Arg389Gly polymorphism may play an important role in predicting the efficacy of flecainide in patients with coadministration of β-blockers.

A Micropatterned Human Pluripotent Stem Cell-Based Ventricular Cardiac Anisotropic Sheet for Visualizing Drug-Induced Arrhythmogenicity

A novel cardiomimetic biohybrid material, termed as the human ventricular cardiac anisotropic sheet (hvCAS) is reported. Well-characterized human pluripotent stem-cell-derived ventricular cardiomyocytes are strategically aligned to reproduce key electrophysiological features of native human ventricle, which, along with specific selection criteria, allows for a direct visualization of arrhythmic spiral re-entry and represents a revolutionary tool to assess preclinical drug-induced arrhythmogenicity.

Flecainide in Amyotrophic Lateral Sclerosis as a Neuroprotective Strategy (FANS): A Randomized Placebo-Controlled Trial

Background

Abnormalities in membrane excitability and Na⁺ channel function are characteristic of amyotrophic lateral sclerosis (ALS). We aimed to examine the neuroprotective potential, safety and tolerability of the Na⁺ channel blocker and membrane stabiliser flecainide in ALS.

Methods

A double-blind, placebo-controlled, randomised clinical trial of flecainide (200 mg/day) for 32-weeks with a 12-week lead-in phase was conducted in participants with probable or definite ALS recruited from multiple Australian centres (ANZCT Registry number ACTRN12608000338369). Patients were reviewed by a cardiologist to rule out cardiac contraindications. Participants were randomly assigned (1:1) to flecainide or placebo using stratified permuted blocks by a central pharmacy. The primary outcome measure was the slope of decline of the ALS Functional Rating Scale-revised (ALS FRS-r) during the treatment period.

Findings

Between March 11, 2008 and July 1, 2010, 67 patients were screened, 54 of whom were randomly assigned to receive flecainide (26 patients) or placebo (28 patients). Four patients in the flecainide group and three patients in the placebo group withdrew from the study. One patient in the flecainide group died during the study, attributed to disease progression. Flecainide was generally well tolerated, with no serious adverse events reported in either group. There was no significant difference in the rate of decline in the primary outcome measure ALS-FRS-r between placebo and flecainide treated patients (Flecainide 0.65 [95% CI 0.49 to 0.98]; Placebo 0.81 [0.49 to 2.12] P = 0.50). However, the rate of decline of the neurophysiological index was significantly reduced in the flecainide group (Flecainide 0.06 [0.01 to 0.11]; Placebo 0.14 [0.09 to 0.19], P = 0.02). Placebo-treated patients demonstrated greater CMAP amplitude reduction during the course of the study in the subset of patients with a reduced baseline CMAP amplitude (Flecainide: − 15 ± 12%; Placebo − 59 ± 12%; P = 0.03). Flecainide-treated patients maintained stabilized peripheral axonal excitability over the study compared to placebo.

Interpretation

This pilot study indicated that flecainide was safe and potentially biologically effective in ALS. There was evidence that flecainide stabilized peripheral axonal membrane function in ALS. While the study was not powered to detect evidence of benefit of flecainide on ALS-FRS-r decline, further studies may demonstrate clinical efficacy of flecainide in ALS.

•

To determine safety and neuroprotective potential, a double-blind, placebo-controlled, randomised trial of the Na⁺ channel blocking agent flecainide was conducted in ALS.

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Flecainide was well tolerated, with no serious adverse events.

•

Although there was some evidence that flecainide stabilised peripheral axonal membrane function, the study was not powered to provide evidence of benefit on functional decline.

Changes in nerve excitability function occur in patients with amyotrophic lateral sclerosis (ALS). We conducted a double-blind, placebo-controlled, randomised clinical trial to examine the impact of a membrane/nerve stabilizer (flecainide) in ALS patients. Although there was some evidence that flecainide stabilised peripheral axonal membrane function in ALS, the study was not powered to find evidence that flecainide benefited patient function.

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.

Sotalol as first-line treatment for fetal tachycardia and neonatal follow-up

OBJECTIVES

In fetal tachycardia, pharmacological therapy with digoxin, flecainide and sotalol has been reported to be effective. In a recent retrospective multicenter study, sotalol was considered to be less effective than the other drugs in treatment of fetal supraventricular tachycardia (SVT). The aim of this study was to re-evaluate the efficacy and safety of maternally administered sotalol in the treatment of fetal tachycardia.

METHODS

This was a retrospective review of the records of 30 consecutive fetuses with tachycardia documented on M-mode echocardiography between January 2004 and December 2010 at Wilhelmina Children's Hospital, a tertiary referral university hospital. Patients were subdivided into those diagnosed with supraventricular tachycardia and those with atrial flutter (AF) and presence of hydrops was noted. Other variables investigated included QTc interval measured on maternal electrocardiogram before and after initiation of antiarrhythmic therapy, fetal heart rhythm and heart rate pre- and postnatally, oral maternal drug therapy used, time to conversion to sinus rhythm (SR), percentage of fetuses converted following transplacental treatment, maternal adverse effects, presence or absence of tachycardia as noted on postnatal ECG, postnatal therapy or prophylaxis and neonatal outcome. Findings are discussed with reference to the literature.

RESULTS

A total of 28 patients (18 with SVT, 10 with AF) were treated with sotalol as first-line therapy. Fetal hydrops was present in six patients (five with SVT, one with AF). All hydropic patients converted antenatally to SR (67% with sotalol as a single-drug therapy, 33% after addition of flecainide). Of the non-hydropic patients, 91% converted to SR (90% with sotalol only, 10% after addition of flecainide or digoxin). In 9% (with AF) rate control was achieved. There was no mortality. No serious drug-related adverse events were observed. Postnatally, rhythm disturbances were detected in 10 patients, two of whom still had AF. In eight, SVT was observed within 3 weeks postnatally, and in five of these within 72 hours.

CONCLUSIONS

Sotalol can be recommended as the drug of first choice for treatment of fetal AF and has been shown to be an effective and safe first-line treatment option for SVT, at least in the absence of hydrops. Postnatal maintenance therapy after successful prenatal therapy is not necessarily indicated, as the risk of recurrence is low beyond 72 hours of age.