Flecainide to prevent atrial arrhythmia after patent foramen ovale closure Rationale and design of the randomized AFLOAT study

INTRODUCTION

Atrial arrhythmia is the most common complication of patent foramen ovale (PFO) closure. The real incidence of post-PFO closure atrial arrhytmia and whether this complication can be prevented is unknown.

METHODS/DESIGN

The Assessment of Flecainide to Lower the patent foramen Ovale closure risk of Atrial fibrillation or Tachycardia (AFLOAT) trial is a prospective, national, multicentre, randomized, open-label, superiority trial with a blind evaluation of all the endpoints (PROBE design). A total of 186 patients are randomized in a 1:1:1 ratio immediately after PFO closure to receive Flecainide (150 mg per day in a single sustained-release dose) for 6 months (Group 1), Flecainide (150 mg per day in a single sustained-release dose) for 3 months (Group 2), or no additional treatment (standard of care) for 6 months (Group 3). The primary endpoint is the percentage of patients with at least one episode of symptomatic or asymptomatic atrial arrhythmia episode (≥30s) recorded within 3 months after PFO closure on long-term monitoring with an insertable cardiac monitor. Whether 3 months of treatment is sufficient compared to 6 months will be analyzed as a secondary objective of the study.

CONCLUSION

AFLOAT is the first trial to test the hypothesis that a short treatment with oral Flecainide can prevent the new-onset of atrial arrhythmia after PFO closure. Clinical trial registration: NCT05213104 (clinicaltrials.gov).

Can specific ECG markers identify a pharmacologically induced type 1 Brugada pattern? Insights from a large, single-center cohort

BACKGROUND

In patients with a type 2 or 3 Brugada pattern, the pharmacological (IC drugs) induction of a type 1 pattern confirms the diagnosis of Brugada syndrome.

OBJECTIVE

To evaluate the value of various ECG markers in predicting IC drug test results.

METHODS

We retrospectively analysed 443 consecutive patients referred to our Center (from January 2010 to December 2019) to undergo Ajmaline/Flecainide testing; all had a type 2 or 3 Brugada pattern or were relatives with Brugada syndrome. Clinical parameters and ECG markers (r1V1 and SV6 duration and amplitude, QRSV1/QRSV6 duration, V1 and V2 ST amplitude) were independently evaluated for their association to pharmacological test positivity, and a logistic regression model was applied.

RESULTS

The drug test was positive in 151 (34%) patients. On multivariate logistic regression analysis, age > 45 years, female gender, HR >60 bpm, QRSV1/QRSV6 duration >1 and non-isoelectric pattern in V2 were associated with a positive test. The percentage of patients who tested positive increased according to the presence of the above ECG markers (from 11.3% in the absence to 57.6% in the presence of both factors). During long-term follow-up, the clinical event rate was higher in patients with predictive ECG markers and very low in those without.

CONCLUSIONS

In our population we confirmed the ability of QRSV1/QRSV6 duration >1 and of a non-isoelectric pattern in V2 to predict a pharmacologically induced type 1 Brugada pattern. Patients with neither of these ECG markers had a rather low event rate during follow-up.

Flecainide administration in children: dosage, drug levels, and clinical effect

Therapeutic drug monitoring of flecainide in children using plasma concentration measurements is undertaken by some clinicians. There is very little published evidence surrounding factors which influence plasma flecainide concentration, particularly in paediatric populations. We undertook a retrospective study of 45 children receiving flecainide to identify factors that influence its plasma concentration. Patients receiving a dose of 6 mg/kg/day had a higher mean plasma flecainide concentration than those receiving lower doses. Younger age and lighter weight were also associated with higher plasma flecainide concentrations. Children aged younger than 1 year receiving flecainide three times a day had a higher mean plasma flecainide concentration than older children who received flecainide twice a day. All supratherapeutic levels occurred in children aged less than 1 year who were receiving flecainide three times a day. Supratherapeutic levels were more common in those receiving 6 mg/kg/day while subtherapeutic levels were more common in those receiving 2 mg/kg/day. A supratherapeutic level did not correlate with adverse effects or clinical toxicity. Our results would suggest the need for a change of practice from prescribing flecainide at a frequency of three times a day in children aged younger than 1 year to twice a day in line with other ages.

Successful treatment of frequent premature ventricular contractions and non-sustained ventricular tachycardia with verapamil and flecainide in RYR1-related myopathy: a case report

Background

Ryanodine receptor 1 (RYR1)-related myopathies are a group of congenital muscle diseases caused by RYR1 mutations. These mutations may cause centronuclear myopathy, a congenital neuromuscular disorder characterized by clinical muscle weakness and pathological presence of centrally placed nuclei on muscle biopsy. Mutations in RYR2 cause ventricular arrhythmias that can be treated with flecainide; however, reports of ventricular arrhythmias in RYR1-related myopathies are rare. Herein we report a case of centronuclear myopathy with RYR1 mutations who exhibited frequent premature ventricular contractions (PVCs) and non-sustained ventricular tachycardia (NSVT), which was successfully treated with verapamil and flecainide.

Case summary

At 7 months, the patient presented neurological manifestations of hypotonia and delayed motor development. A skeletal muscle biopsy performed at age 4 years led to the diagnosis of centronuclear myopathy. At age 15 years, frequent PVCs and NSVT were identified on the electrocardiogram and 24 h Holter monitoring. Treatment with verapamil was initiated; however, it was not beneficial. Therefore, flecainide was added to the treatment, decreasing the frequency of PVCs and NSVT. Non-sustained ventricular tachycardia disappeared at the age of 21, and PVCs almost disappeared at the age of 22. Genetic testing revealed c.13216delG (p.E4406Rfs*35), c.14874G>C (p.K4958N), and c.9892G>A (p.A3298T) in RYR1, and the compound heterozygosity of variants was confirmed by analysis of the parents.

Discussion

This is the first report of ventricular arrhythmia associated with RYR1-related myopathy that was successfully treated with verapamil and flecainide. The combination of verapamil and flecainide may be a useful treatment option for ventricular arrhythmias in patients with RYR1-related myopathies.

Flecainide for conversion and maintenance of sinus rhythm after mitral valve replacement in rheumatic atrial fibrillation

BACKGROUND

Despite successful mitral valve replacement (MVR), many patients remain in AF. Flecainide can be useful in these patients but has not been used because of underlying structural heart disease.

METHODS

We assessed oral flecainide for conversion and maintenance of SR in 25 patients of chronic rheumatic AF following MVR (age 34.4 yrs, mean AF duration: 3.6 yrs). Non-converters underwent DC cardioversion at 24 h and 4 weeks. Patients received flecainide and bb/diltiazem at discharge.

RESULTS

Single oral dose of Flecainide achieved SR in 6/25 (24%) while 19/25 achieved SR after DCC; at24 h 21/25 (84%) were in SR. With mean flecainide dose (93.10 ± 9.40 mg), successful maintenance of SR at 6 months was seen in 16/23 (69.5%). No significant changes in PR interval, QRS duration or QTc were noted; flecainide was well tolerated. Patients in SR had significantly better functional status, QOL scores and higher LA strain at 6 months (25.25 vs 17.43%, p < .0001). Baseline LA diameter ≤ 61 mm predicted SR at 6 months (sensitivity/specificity 93.7% and 85.71%) while the values for AF duration ≤ 4 years and LA strain > 21% for predicting SR were 87.5/71.43% and 100/85.71% respectively.

CONCLUSION

Oral flecainide was safe and effective in post MVR rheumatic AF patients; maintenance of SR was achieved in 76% of initial converters and 64% of overall population, with better LA strain values. More studies are needed to validate these results.

Mild elevation of extracellular potassium greatly potentiates the effect of sodium channel block to cardiovert atrial fibrillation: The Lankenau approach

BACKGROUND

Cardioversion of atrial fibrillation (AF) is a common clinical necessity, and there is a need for more effective and safe options for acute cardioversion of AF.

OBJECTIVE

The purpose of this study was to test the hypothesis that the efficacy and time course of AF cardioversion by sodium channel current (INa) block can be improved by mild elevation of extracellular potassium ([K+]0).

METHODS

Using a canine acetylcholine (ACh)-mediated AF model (isolated coronary-perfused right atrial preparations with a rim of right ventricle), we evaluated the ability of flecainide to suppress AF in the presence of [K+]0 ranging from 3 to 8 mM.

RESULTS

At [K+]0 of 4 mM (baseline), persistent AF (>1 hour) was induced in 5 of 5 atria in the presence of 0.5 μM ACh. Flecainide alone (1.5 μM) cardioverted 3 of 6 atria at 4 mM [K+]0, 1 of 6 atria at 3 mM [K+]0, 5 of 5 atria at 5 mM and 6 mM [K+]0, and 4 of 4 atria at 8 mM [K+]0. In the absence of flecainide, an increase in [K+]0 from 4 mM to 5, 6, and 8 mM terminated AF in 0 of 5, 2 of 6, and 4 of 4 atria, respectively. The time to conversion was also abbreviated by elevation of [K+]0. After AF termination with flecainide plus elevated [K+]0, AF was either not inducible or brief (<100 seconds). Combined flecainide and elevated [K+]0 (6 mM) caused an atrial preferential depression of excitability.

CONCLUSION

Our findings suggest that a combination of INa block accompanied by mild elevation of serum potassium may be a novel approach to more effectively, rapidly, and safely cardiovert AF and prevent its recurrence in the short term.

Catecholaminergic Polymorphic Ventricular Tachycardia: A Review of Therapeutic Strategies

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmia syndrome characterized by bidirectional or polymorphic ventricular arrhythmia provoked by exercise or emotion. Most cases are caused by pathogenic variants in the gene encoding the cardiac ryanodine receptor (RYR2). The options for treating patients with CPVT have increased during the years, and evidence suggests that these have led to lower arrhythmic event rates. In addition, numerous potential new therapies are being investigated. In this review, we summarize the state of knowledge on both established and potential future treatment strategies for patients with CPVT and describe our approach to their management.

Failure of diltiazem to prevent 1:1 conduction of atrial flutter: a case report

BACKGROUND

Atrial flutter with 1:1 conduction to the ventricles is a dangerous cardiac arrhythmia. Contemporary guidelines recommend atrioventricular nodal blocking agents should be co-administered with class 1C anti-arrhythmics, as prophylaxis against 1:1 flutter. No guidance is provided on the type or strength of atrioventricular nodal blockade required, and in practice, these agents are frequently prescribed at low dose, or even omitted, due to their side effect profile.

CASE PRESENTATION

A 62 year old Caucasian man with a history of paroxysmal atrial fibrillation treated with flecainide, presented with atrial flutter with 1:1 conduction to the ventricles and was cardioverted. Diltiazem was added to prevent this complication and he again presented with atrial flutter with 1:1 conduction to the ventricles, despite prophylaxis with coadministration of diltiazem.

CONCLUSIONS

This case report demonstrates failure of diltiazem to prevent 1:1 flutter in a patient chronically treated with flecainide for paroxysmal atrial fibrillation.

A Case of Flecainide-Induced Hyponatremia

The complex classification for the diagnosis and treatment illustrates that hyponatremia is a very heterogeneous disorder. However, data on hyponatremia induced by flecainide, an often-prescribed antiarrhythmic agent, are scarce in the literature. A 78-year-old man with a recent history of recurrent hyponatremia and symptomatic paroxysmal atrial fibrillation presented with the complaints of dizziness and fatigue. During his repeated hospital admissions, the patient was treated with hypertonic saline, which temporarily improved serum sodium levels, but hyponatremia recurred without sustained clinical improvement. After discontinuation of the drug, the sodium levels remained stable. Doctors should be aware of not only the electrocardiographic changes associated with flecainide, but also the less-often found clinical manifestations linked with hyponatremia.

Maternal, fetal, neonatal and breastmilk flecainide concentration during maternal therapy and lactation: a case report

BACKGROUND

Mothers requiring the antiarrhythmic agent flecainide are often advised not to breastfeed, because of the lack of data concercing neonatal effects and flecainide plasma concentrations following maternal exposure as well as via lactation. This is the first report on combined maternal, fetal, neonatal and breastmilk flecainide concentrations in a breastfed infant of a mother requiring flecainide treatment.

CASE PRESENTATION

A 35-year old Gravida 2 Para 1, known with ventricular arrhythmia, was referred to our tertiary center at 35 + 4 weeks of gestation. Because of an increase of ventricular ectopy, oral metoprolol 11.9 milligrams once daily was switched to oral flecainide 87.3 milligrams twice daily. Weekly collected maternal flecainide plasma trough concentrations fell within the therapeutic range of 0.2 to 1.0 mg/L and no further clinically significant arrhythmias occurred during the study period. A healthy son was born at 39 weeks of gestation and had a normal electrocardiogram. The fetal to maternal flecainide ratio was 0.72 and at three different timepoints, the flecainide concentration was higher in breastmilk than in maternal plasma. The relative infant dose received via breastmilk compared to maternal dose was 5.6%. Neonatal plasma concentrations were not detectable, despite the flecainide passage into breastmilk. All electrocardiograms to assess the neonatal antiarrhytmic effect were normal.

CONCLUSIONS

Our results assume that flecainide can be prescribed safely to lactating mothers. Quantification of drug concentrations in neonatal blood in addition to measurements in maternal and fetal blood, and breastmilk, are helpful to evaluate the effects and safety of maternal medication use during pregnancy and lactation.

Modulation of cardiac ventricular conduction: Impact on QRS duration, amplitude and dispersion

Alterations in cardiac impulse conduction may exert both beneficial and detrimental effects. The assessment of ventricular conduction properties is of paramount importance both in clinical and in experimental settings. Currently the duration of the QRS complex is regarded as hallmark of in-vivo assessment of global ventricular conduction time. In addition, the amplitude of the QRS complex has been suggested to reflect ventricular conduction time in man and in rats. Here, for the first time, we systematically investigated the relationship between QRS duration ("QRS") and QRS amplitude ("RS-height"; RSh) in the murine ECG obtained during anesthesia. In mice harbouring a homozygous knockout of the transmembrane protein podoplanin (PDPN-/-; n = 10) we found both a shorter QRS and a greater RSh than in wild-type animals (n = 13). In both genotypes cumulative i.p. administration of 5 mg/kg and 10 mg/kg of the Na channel blocker flecainide resulted in dose-dependent QRS increase and RSh decrease, whereby the drug-induced changes in RSh were greater than in QRS. In both genotypes the flecainide-induced changes in QRS and in RSh were significantly correlated with each other (R = -0.56, P = 0.004). Whereas dispersion of QRS and RSh was similar between genotypes, dispersion of the ratio QRS/RSh was significantly smaller in PDPN-/- than in wild-types. We conclude that in the murine ECG QRS is inversely related to RSh. We suggest that both parameters should be considered in the analysis of ventricular conduction time in the murine ECG.

Flecainide-induced pneumonitis: a case report

BACKGROUND

We report a case of acute respiratory distress associated with a histological pattern of acute fibrinous and organizing pneumonia, and discuss the possible responsibility of flecainide therapy.

CASE PRESENTATION

A 61-year-old African woman developed a rapidly progressive dyspnea and required admission in the intensive care unit for orotracheal intubation and mechanical ventilation. Chest X-ray examination revealed bilateral infiltrates predominating in the basal part of both lungs. Lung computed tomography disclosed bilateral ground-glass opacities and septal thickening. After exclusion of the most common causes of infectious or immune pneumonia, a toxic origin was investigated and flecainide toxicity was considered. Lung biopsy was consistent with the unusual pattern of acute fibrinous and organizing pneumonia. Clinical and radiological improvement was noted after corticosteroid therapy, but the patient died from septic complications.

CONCLUSION

Flecainide-induced lung injury has rarely been reported in the literature and remains a diagnosis of exclusion. The histological pattern of acute fibrinous and organizing pneumonia has been previously observed with amiodarone. There are no firm guidelines for the treatment of acute fibrinous and organizing pneumonia, but some patients may positively respond to corticosteroids.

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.

at rest: a case report

Background 

Class IC antiarrhythmic drug flecainide is commonly used in the management of atrial arrhythmias and in particular atrial fibrillation (AF). Although previously reported as a potential complication, atrial flutter (AFL) with 1:1 atrioventricular (AV) conduction is rare, with only few cases reported so far, most of which related to physical activity. In all previous reported cases, 1:1 conduction resulted in ventricular rates of >200 b.p.m.

Case summary 

We report the case of a 60-year-old woman, who presented to our local emergency department with palpitations related to acute onset AF. The patient developed symptomatic 1:1 AFL with a rate of 192 b.p.m., shortly after administration of intravenous flecainide, which spontaneously converted back to AF and subsequently to sinus rhythm, with further administration of amiodarone and beta-blocker.

Discussion 

The case raises awareness of this rare but potentially life-threatening complication to those using flecainide for pharmacological cardioversion of AF. QRS complex widening can be seen in the context of very rapid ventricular rates, posing additional diagnostic challenge, especially with rates of <200 b.p.m. Prescribing an AV nodal blocking agent, such as a beta-blocker, together with flecainide reduces significantly the risk of 1:1 conduction and should always be considered.

flecainide in the maintenance of sinus rhythm, following electrocardioversion in adults with persistent atrial fibrillation: a systematic review and meta-analysis

AIMS

To compare flecainide and dronedarone for sinus rhythm (SR) maintenance following electrocardioversion of persistent atrial fibrillation (AF), in patients with minimal or no structural heart disease.

METHODS AND RESULTS

A systematic search of publications using EMBASE, CENTRAL, CINAHL, and MEDLINE (1989-2019), identified a total of 595 articles. No limitations were applied. Nine articles met the inclusion criteria [five randomized controlled trials (RCTs) and four cohort studies], encompassing 1349 persistent AF candidates. Two retrospective studies compared flecainide with dronedarone, indicating a 6% reduced risk of AF recurrence with flecainide; however, results were not statistically significant [risk ratio (RR) 0.94, 95% confidence interval (CI) 0.71-1.24; P = 0.66]. One RCT compared dronedarone to placebo, demonstrating a 28% reduced risk of AF recurrence at 6 months (RR 0.72, 95% CI 0.58-0.90; P = 0.004). Two RCTs compare flecainide to placebo, when a 16% decreased risk of AF recurrence at 6-12 months was indicated; however, these results were not statistically significant (RR 0.84, 95% CI 0.66-1.07; P = 0.16). Within a 6- to 12-month follow-up period, a combined recurrence rate of AF was examined, in which flecainide and dronedarone maintained SR in 50% and 42%, respectively. Four articles satisfied quality appraisal, one of which focused on flecainide data.

CONCLUSION

Dronedarone and flecainide displayed similar efficacy in maintaining SR in patients following electrocardioversion for persistent AF. The SR maintenance was numerically but not statistically significant in the flecainide group. Side effects uncovered similar pro-arrhythmic activity. However, in light of the deficiency of volume and quality of available evidence, the writer acknowledges the requirement for future research.

Safety and efficacy of flecainide associated with beta-blockers in arrhythmogenic right ventricular cardiomyopathy

AIMS

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited cardiomyopathy associated with a high risk of ventricular arrhythmia (VA). Current guidelines recommend beta-blockers as first-line medical therapy and if ineffective, sotalol or amiodarone. We describe our experience, as a tertiary centre for ARVC, with the effectiveness and tolerance of flecainide in addition to beta-blockers to prevent VA in ARVC.

METHODS AND RESULTS

We retrospectively included 100 consecutive ARVC patients who received flecainide with beta-blockers between May 1999 and November 2017. Treatment persistence and related side effects were assessed, as was VA-free survival on treatment, 24-h Holter monitoring and programmed ventricular stimulation (PVS) off- and on-treatment. Tolerance was good, with 10% flecainide discontinuations (lack of efficacy in six, atrial fibrillation in one, and side effects in three). No Brugada-induced electrocardiography pattern on flecainide or haemodynamic impairment was reported. Premature ventricular contraction burden at 24-h Holter monitoring was significantly decreased under treatment [median 415 (interquartile range, IQR 97-730) vs. 2370 (1572-3400) at baseline, P < 0.0001, n = 46]. Among the 33 patients with PVS under treatment, PVS was positive in 40% on-treatment vs. 94% off-treatment (P < 0.001). During a median follow-up of 47 months (IQR 23-73), 22 patients presented sustained VA on treatment, corresponding to an event rate of 5% [95% confidence interval (CI) (0.6-9)] at 1 year and 25% [95% CI (14-35)] at 5 years under treatment. No patient died.

CONCLUSION

This study suggests that flecainide and beta-blockers association is complementary to implantable cardioverter-defibrillator and catheter ablation and is safe for treating persistent symptomatic VA in patients with ARVC.

Wide complex tachycardia in dialysis patients is not always hyperkalemia

BACKGROUND

Flecainide is a commonly used IC antiarrhythmic. Clinical presentations of Flecainide toxicity are not commonly described.

CASE REPORT

A 62 year old man on dialysis presented for evaluation of outpatient bradycardia and hypotension. In the ED, patient had wide-complex rhythm with heart rates ranging from 76 to 127. The previous day, Flecainide and Metoprolol were discontinued and patient was dialyzed and discharged. The patient was treated empirically for possible hyperkalemia. No significant change in ECG was noted with administration of calcium. Sodium bicarbonate produced questionable benefit. Potassium level was 4.6 mmol/L. Cardiac rhythm fluctuated between sinus rhythm and wide complex tachycardia in the ED & ICU. Flecainide level was 2.1 μg/ml (normal <1 μg/ml). Toxicity developed despite previous discontinuation and dialysis prior to presentation because of Flecainide's large volume of distribution and lipopholicity. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Although Flecainide toxicity is uncommon, it has a high mortality rate, requiring early identification and treatment. Flecainide toxicity can develop in patients with hepatic or renal insufficiency, and can manifest with ventricular tachycardia or bradycardia. If suspicion of Flecainide toxicity arises, lidocaine and procainamide should be avoided to prevent further sodium channel blockade. Absence of response to calcium for a very wide complex QRS should raise clinicians' suspicion that WCT is not due to hyperkalemia, emphasizing the importance of reviewing patients' home medications. Sodium bicarbonate should be administered early to treat widened QRS. Amiodarone, intralipid emulsion therapy and ECMO may be considered in severe cases.

Mechanisms of flecainide induced negative inotropy: An in silico study

It is imperative to develop better approaches to predict how antiarrhythmic drugs with multiple interactions and targets may alter the overall electrical and/or mechanical function of the heart. Safety Pharmacology studies have provided new insights into the multi-target effects of many different classes of drugs and have been aided by the addition of robust new in vitro and in silico technology. The primary focus of Safety Pharmacology studies has been to determine the risk profile of drugs and drug candidates by assessing their effects on repolarization of the cardiac action potential. However, for decades experimental and clinical studies have described substantial and potentially detrimental effects of Na⁺ channel blockers in addition to their well-known conduction slowing effects. One such side effect, associated with administration of some Na⁺ channel blocking drugs is negative inotropy. This reduces the pumping function of the heart, thereby resulting in hypotension. Flecainide is a well-known example of a Na⁺ channel blocking drug, that exhibits strong rate-dependent block of I_Na and may cause negative cardiac inotropy. While the phenomenon of Na⁺ channel suppression and resulting negative inotropy is well described, the mechanism(s) underlying this effect are not. Here, we set out to use a modeling and simulation approach to reveal plausible mechanisms that could explain the negative inotropic effect of flecainide. We utilized the Grandi-Bers model [1] of the cardiac ventricular myocyte because of its robust descriptions of ion homeostasis in order to characterize and resolve the relative effects of QRS widening, flecainide off-target effects and changes in intracellular Ca²⁺ and Na⁺ homeostasis. The results of our investigations and predictions reconcile multiple data sets and illustrate how multiple mechanisms may play a contributing role in the flecainide induced negative cardiac inotropic effect.

Flecainide-induced QRS complex widening correlates with negative inotropy

BACKGROUND

The negative inotropic effect of Class IC antiarrhythmic drugs limits their use for acute cardioversion of atrial fibrillation (AF).

OBJECTIVE

The purpose of this study was to examine, in an intact porcine model, the effects of pulmonary and intravenous (IV) administration of flecainide on left ventricular (LV) contractility and QRS complex width at doses that are effective in converting new-onset AF to sinus rhythm.

METHODS

Flecainide (1.5 mg/kg bolus) was delivered by intratracheal administration and compared to 2.0 mg/kg 10-minute IV administration (European Society of Cardiology guideline) and to 0.5 and 1.0 mg/kg 2-minute IV doses in 40 closed-chest, anesthetized Yorkshire pigs. Catheters were fluoroscopically positioned in the LV to monitor QRS complex width and contractility and at the bifurcation of the main bronchi to deliver intratracheal flecainide.

RESULTS

Peak flecainide plasma concentrations (C_max) were similar, but the 30-minute area under the curve (AUC) of plasma levels was 1.4- to 2.8-fold greater for 2.0 mg/kg 10-minute IV infusion than for the lower, more rapidly delivered intratracheal and IV doses. AUC for LV contractility (ie, negative inotropic burden) was 2.2- to 3.6-fold greater for 2.0 mg/kg 10-minute IV dose than for the lower, more rapidly delivered doses. QRS complex widening by flecainide was highly correlated with the decrease in LV contractility (r² = 0.890, P <.0001, for all IV doses; r² = 0.812, P = .01, for intratracheal flecainide).

CONCLUSION

QRS complex widening in response to flecainide is strongly correlated with decrease in LV contractility. Rapid pulmonary or IV flecainide delivery reduces the negative inotropic burden while quickly achieving C_max levels associated with conversion of AF.

Atrial resting membrane potential confers sodium current sensitivity to propafenone, flecainide and dronedarone

BACKGROUND

Although atrial fibrillation ablation is increasingly used for rhythm control therapy, antiarrhythmic drugs (AADs) are commonly used, either alone or in combination with ablation. The effectiveness of AADs is highly variable. Previous work from our group suggests that alterations in atrial resting membrane potential (RMP) induced by low Pitx2 expression could explain the variable effect of flecainide.

OBJECTIVE

The purpose of this study was to assess whether alterations in atrial/cardiac RMP modify the effectiveness of multiple clinically used AADs.

METHODS

The sodium channel blocking effects of propafenone (300 nM, 1 μM), flecainide (1 μM), and dronedarone (5 μM, 10 μM) were measured in human stem cell-derived cardiac myocytes, HEK293 expressing human Na_V1.5, primary murine atrial cardiac myocytes, and murine hearts with reduced Pitx2c.

RESULTS

A more positive atrial RMP delayed I_Na recovery, slowed channel inactivation, and decreased peak action potential (AP) upstroke velocity. All 3 AADs displayed enhanced sodium channel block at more positive atrial RMPs. Dronedarone was the most sensitive to changes in atrial RMP. Dronedarone caused greater reductions in AP amplitude and peak AP upstroke velocity at more positive RMPs. Dronedarone evoked greater prolongation of the atrial effective refractory period and postrepolarization refractoriness in murine Langendorff-perfused Pitx2c^+/- hearts, which have a more positive RMP compared to wild type.

CONCLUSION

Atrial RMP modifies the effectiveness of several clinically used AADs. Dronedarone is more sensitive to changes in atrial RMP than flecainide or propafenone. Identifying and modifying atrial RMP may offer a novel approach to enhancing the effectiveness of AADs or personalizing AAD selection.

Supraventricular tachycardias in the first year of life: what is the best pharmacological treatment? 24 years of experience in a single centre

Background

Supraventricular tachycardias (SVTs) are common in the first year of life and may be life-threatening. Acute cardioversion is usually effective, with both pharmacological and non-pharmacological procedures. However, as yet no international consensus exists concerning the best drug required for a stable conversion to sinus rhythm (maintenance treatment). Our study intends to describe the experience of a single centre with maintenance drug treatment of both re-entry and automatic SVTs in the first year of life.

Methods

From March 1995 to April 2019, 55 patients under one year of age with SVT were observed in our Centre. The SVTs were divided into two groups: 45 re-entry and 10 automatic tachycardias. As regards maintenance therapy, in re-entry tachycardias, we chose to start with oral flecainide and in case of relapses switched to combined treatment with beta-blockers or digoxin. In automatic tachycardias we first administered a beta-blocker, later combined with flecainide or amiodarone when ineffective.

Results

The patients’ median follow-up time was 35 months. In re-entry tachycardias, flecainide was effective as monotherapy in 23/45 patients (51.1%) and in 20/45 patients (44.4%) in combination with nadolol, sotalol or digoxin (overall 95.5%). In automatic tachycardias, a beta-blocker alone was effective in 3/10 patients (30.0%), however, the best results were obtained when combined with flecainide: overall 9/10 (90%).

Conclusions

In this retrospective study on pharmacological treatment of SVTs under 1 year of age the combination of flecainide and beta-blockers was highly effective in long-term maintenance of sinus rhythm in both re-entry and automatic tachycardias.

The Efficacy of Anti-Arrhythmic Drugs in Children With Idiopathic Frequent Symptomatic or Asymptomatic Premature Ventricular Complexes With or Without Asymptomatic Ventricular Tachycardia: a Retrospective Multi-Center Study

The aim of the study is to compare the efficacy of flecainide, beta-blockers, sotalol, and verapamil in children with frequent PVCs, with or without asymptomatic VT. Frequent premature ventricular complexes (PVCs) and asymptomatic ventricular tachycardia (VT) in children with structurally normal hearts require anti-arrhythmic drug (AAD) therapy depending on the severity of symptoms or ventricular dysfunction; however, data on efficacy in children are scarce. Both symptomatic and asymptomatic children (≥ 1 year and < 18 years of age) with a PVC burden of 5% or more, with or without asymptomatic runs of VT, who had consecutive Holter recordings, were included in this retrospective multi-center study. The groups of patients receiving AAD therapy were compared to an untreated control group. A medication episode was defined as a timeframe in which the highest dosage at a fixed level of a single drug was used in a patient. A total of 35 children and 46 medication episodes were included, with an overall change in PVC burden on Holter of -4.4 percentage points, compared to -4.2 in the control group of 14 patients. The mean reduction in PVC burden was only significant in patients receiving flecainide (- 13.8 percentage points; N = 10; p = 0.032), compared to the control group and other groups receiving beta-blockers (- 1.7 percentage points; N = 18), sotalol (+ 1.0 percentage points; N = 7), or verapamil (- 3.9 percentage points; N = 11). The efficacy of anti-arrhythmic drug therapy on frequent PVCs or asymptomatic VTs in children is very limited. Only flecainide appears to be effective in lowering the PVC burden.

A pilot study on the acute conversion and maintenance of sinus rhythm in rheumatic atrial fibrillation using oral flecainide

Background

Achievement of sinus rhythm (SR) is an important goal in rheumatic atrial fibrillation (AF). Studies in rheumatic AF have often used amiodarone for rhythm control. Flecainide has not been studied in these patients due to concerns of underlying structural heart disease.

Methods

Pharmacological cardioversion by oral single loading dose (SLD) of Flecainide (4 mg/kg, ≤300 mg) was tested in 50 patients with rheumatic AF (MVA 1.51 ± 0.19 mm², age 46.2 ± 10.28 yrs, AF duration 3.10 ± 1.7 yrs, LA size: 44.42 ± 7.48 mm). Non-converters underwent DC cardioversion (DCC) at 24 h. All patients received oral flecainide and ββ/diltiazem at discharge.

Results

At 24 h, 38/50 (76%) achieved SR (2 with SLD; 36 after DCC). At 30 days (mean Flecainide dose 116.5 ± 10.5 mg) successful maintenance of SR was noted in 31/38 (89%). At 1 year, 30/38 (79%) of the initial converters and 60% of the overall population maintained SR. Those in SR had significantly better NYHA Class (1.1 ± 0.12 vs 1.3 ± 0.10, p = 0.03) and mean PCS8 score (50.11 ± 5.337 vs 46.84 ± 5.379, p = 0.02). AF duration (OR 0.594 CI 0.375–0.940, p = 0.02) and LA size (OR 0.840, CI 0.757–0.933, p = 0.001) were found to be the only significant predictors of successful outcomes. Patients with AF duration <3.5 years and LA size <51 mm had 85% and 75% chance of maintaining SR at 1 year, respectively.

Conclusion

Flecainide is safe and effective for achieving and maintaining SR in patients of rheumatic AF who are unlikely to have underlying coronary artery disease or ventricular dysfunction.

Flecainide improves cardiac synchronization in an early infant with Wolff-Parkinson-White syndrome with left ventricular dyssynchrony

Recently, cases of pharmacological resynchronization for Wolff-Parkinson-White syndrome (WPWS) in children with left ventricular dyssynchrony (LVD) were reported, but an appropriate pharmacological therapy has not yet been established. A 3-month-old, previously healthy female patient was referred to our hospital due to supraventricular tachycardia (SVT). After resolution of the SVT, 12-lead electrocardiography (ECG) showed ventricular pre-excitation. Transthoracic echocardiography showed LVD with no findings of congenital heart disease or cardiomyopathy. To prevent SVT recurrence, oral propranolol administration was started, but the SVT recurred one month later. To prevent further recurrences, oral flecainide administration was started, as the patient's body weight was insufficient for catheter ablation to be performed safely. When the flecainide dosage was increased to 50 mg/m²/day, the pre-excitation resolved, and the LVD improved. Holter ECG showed that the resolution of pre-excitation depended on the serum concentration of flecainide. There are only few reports on pharmacological resynchronization in WPWS patients with LVD (LVD-WPWS). The present report is the first to examine the efficacy of flecainide in patients with recurrent SVT. Flecainide may be a safe and effective alternative resynchronization therapy for LVD-WPWS patients, especially for children in whom catheter ablation cannot be performed safely due to insufficient body weight. <Learning objective: While cases of pharmacological resynchronization for Wolff-Parkinson-White syndrome (WPWS) in children with left ventricular dyssynchrony (LVD) have been reported, an appropriate pharmacological therapy has yet to be established. Flecainide may be a safe and effective alternative resynchronization therapy for WPWS with LVD, especially for children in whom catheter ablation cannot be performed safely due to insufficient body weight.>.

[A case of systemic sclerosis]

In systemic sclerosis, the presence of an anti-RNA polymerase III antibody (ARNpol3) is associated with an increased risk of cancer. The characteristic picture of this serotype includes severe diffuse cutaneous involvement, a high risk of renal scleroderma crisis and a 10 year survival of only around 30%. Pulmonary involvement is less common. We report the case of a woman initially treated for drug-induced acute interstitial lung disease revealing chronic interstitial pneumonia with autoimmune features. The disease evolved in three stages with the occurrence of a rapidly progressive diffuse skin sclerosis with anti-ARNPol3 antibodies in the context of ovarian cancer remission.

A pharmacological characterization of electrocardiogram PR and QRS intervals in conscious telemetered rats

INTRODUCTION

The conscious telemetered rat is widely used as an early in vivo screening model for assessing the cardiovascular safety of novel pharmacological agents. The current study aimed to identify its utility in assessing electrocardiogram (ECG) PR and QRS interval changes.

METHOD

Male Han-Wistar rats (~250 g) were implanted with radio-telemetry devices for the recording of ECG and haemodynamic parameters. Animals (n = 4-8) were treated with single doses of calcium (nifedipine, diltiazem or verapamil; CCBs) or sodium channel blockers (quinidine or flecainide; SCBs) or their corresponding vehicles in an ascending dose design. Data was recorded continuously up to 24 h post-dose. Pharmacokinetic analysis of blood samples was performed to allow comparison of effects to published data in other species.

RESULTS

Of the CCBs, only diltiazem (300 mg/kg) prolonged the PR interval (49 ± 2 versus vehicle: 43 ± 1 ms), although this was not statistically significant (p = .11). QA interval decreased with nifedipine (30 ± 1 versus 24 ± 0 ms) and diltiazem (34 ± 1 versus 27 ± 1 ms) but increased with verapamil (30 ± 0 versus 37 ± 1 ms) demonstrating pharmacological activity of each agent. Both SCBs, caused statistically significant (p < .05) increases in both intervals - quinidine (100 mg/kg; PR: 50 ± 2 versus 43 ± 1 ms; QRS: 22 ± 2 versus 18 ± 1 ms) and flecainide (9 mg/kg; PR: 56 ± 1 versus 46 ± 1 ms; QRS: 27 ± 1 versus 21 ± 1 ms). Drug plasma exposure was confirmed in all animals.

DISCUSSION

At similar plasma concentrations to other species, the conscious telemetered rat demonstrates limited utility in assessing PR interval prolongation by CCBs, despite significant contractility effects being observed. However, results with SCBs demonstrate a potential application for evaluating drug-induced QRS prolongation.

Mutation-specific differences in arrhythmias and drug responses in CPVT patients: simultaneous patch clamp and video imaging of iPSC derived cardiomyocytes

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited cardiac disease characterized by arrhythmias under adrenergic stress. Mutations in the cardiac ryanodine receptor (RYR2) are the leading cause for CPVT. We characterized electrophysiological properties of CPVT patient-specific induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) carrying different mutations in RYR2 and evaluated effects of carvedilol and flecainide on action potential (AP) and contractile properties of hiPSC-CMs. iPSC-CMs were generated from skin biopsies of CPVT patients carrying exon 3 deletion (E3D) and L4115F mutation in RYR2. APs and contractile movement were recorded simultaneously from the same hiPSC-CMs. Differences in AP properties of ventricular like CMs were seen in CPVT and control CMs: APD90 of both E3D (n = 20) and L4115F (n = 25) CPVT CMs was shorter than in control CMs (n = 15). E3D-CPVT CMs had shortest AP duration, lowest AP amplitude, upstroke velocity and more depolarized diastolic potential than controls. Adrenaline had positive and carvedilol and flecainide negative chronotropic effect in all hiPSC CMs. CPVT CMs had increased amount of delayed after depolarizations (DADs) and early after depolarizations (EADs) after adrenaline exposure. E3D CPVT CMs had the most DADs, EADs, and tachyarrhythmia. Discordant negatively coupled alternans was seen in L4115F CPVT CMs. Carvedilol cured almost all arrhythmias in L4115F CPVT CMs. Both drugs decreased contraction amplitude in all hiPSC CMs. E3D CPVT CMs have electrophysiological properties, which render them more prone to arrhythmias. iPSC-CMs provide a unique platform for disease modeling and drug screening for CPVT. Combining electrophysiological measurements, we can gain deeper insight into mechanisms of arrhythmias.

Longitudinal study of electrical, functional and structural remodelling in an equine model of atrial fibrillation

Background

Large animal models are important in atrial fibrillation (AF) research, as they can be used to study the pathophysiology of AF and new therapeutic approaches. Unlike other animal models, horses spontaneously develop AF and could therefore serve as a bona fide model in AF research. We therefore aimed to study the electrical, functional and structural remodelling caused by chronic AF in a horse model.

Method

Nine female horses were included in the study, with six horses tachypaced into self-sustained AF and three that served as a time-matched sham-operated control group. Acceleration in atrial fibrillatory rate (AFR), changes in electrocardiographic and echocardiographic variables and response to medical treatment (flecainide 2 mg/kg) were recorded over a period of 2 months. At the end of the study, changes in ion channel expression and fibrosis were measured and compared between the two groups.

Results

AFR increased from 299 ± 33 fibrillations per minute (fpm) to 376 ± 12 fpm (p < 0.05) and atrial function (active left atrial fractional area change) decreased significantly during the study (p < 0.05). No changes were observed in heart rate or ventricular function. The AF group had more atrial fibrosis compared to the control group (p < 0.05). No differences in ion channel expression were observed.

Conclusion

Horses with induced AF show signs of atrial remodelling that are similar to humans and other animal models.

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.

An irregular, extremely broad QRS complex rhythm

We report a case of a 74-year-old lady admitted to the emergency department with a very broad QRS complex caused by flecainide intoxication due to acute renal failure. Appropriate recognition of the ECG changes and symptoms provoked by flecainide intoxication permitted quick directed treatment with intravenous administration of high dose sodium bicarbonate, which resolved the QRS elongation.

Specific Therapy Based on the Genotype in a Malignant Form of Long QT3, Carrying the V411M Mutation

Congenital long QT syndrome (LQTS) is a cardiac channelopathy that leads to the prolongation of the QT interval. This prolongation can lead to ventricular tachyarrhythmia, syncope, and sudden cardiac death. There are various types of LQTS. Treatment of LQT1 and LQT2 is mainly based on antiadrenergic therapy. LQT3, on the other hand, is a result of a mutation of the SCN5A gene, which encodes the sodium channels. In this type, patients are sensitive to vagal stimuli and episodes tend to occur at rest. Sodium channel blocking compounds, such as ranolazine, mexiletine, and flecainide, have been found to be effective in selective mutations.In this case report, we report the case of a child with congenital LQT3 (V411M) who presented first with sudden cardiac death and three weeks later with an implantable cardioverter defibrillator storm. Knowing the specific mutation and understanding the mechanism at the molecular level through an in vitro study yielded a clinically meaningful result. The patient's arrhythmia burden was totally eliminated following successful treatment with flecainide.

Flecainide is a safe and effective treatment for pre-excited atrial fibrillation rapidly conducted to the ventricle in pregnant women: a case series

Background

Pregnancy is associated with an increased incidence of cardiac arrhythmias likely due to hormonal, haemodynamic, and autonomic changes. Yet, there is little data available regarding the efficacy and safety of anti-arrhythmic agents to prevent pre-excited atrial fibrillation (AF) in pregnant women.

Case summary

We report on three pregnant women who developed AF rapidly conducted to the ventricle through an overt accessory pathway as the first manifestation of Wolff–Parkinson–White syndrome.

Discussion

All patients were treated with flecainide with neither arrhythmias recurrence nor adverse events of the treatment. Mechanisms of action and clinical efficacy of flecainide are discussed.

Optimizing flecainide plasma concentration profile for atrial fibrillation conversion while minimizing adverse ventricular effects by rapid, low-dose intratracheal or intravenous administration

BACKGROUND

We investigated whether rapid administration of a low dose of flecainide, either intratracheally or intravenously (IV), could accelerate conversion of atrial fibrillation (AF) while reducing adverse ventricular effects.

METHODS

Flecainide was delivered via intratracheal administration at 1.5 mg/kg bolus and compared to IV infusion at 1.0 mg/kg over 2 min (lower-dose, rapid) and 2.0 mg/kg over 10 min (ESC guideline) in closed-chest, anesthetized Yorkshire pigs. Catheters were fluoroscopically positioned in right atrium to measure atrial depolarization (Pa) duration and left ventricle (LV) to measure QRS complex duration and contractility (LV dP/dt) during atrial pacing at 140 beats/min. Flecainide was delivered intratracheally via a catheter positioned at the bifurcation of the main bronchi. AF was induced by intrapericardial administration of acetylcholine followed by burst pacing.

RESULTS

Flecainide reduced AF duration similarly by intratracheal and IV delivery. Peak plasma levels were comparable but Tmax differed and coincided with peaks in Pa prolongation. The area under the curve indicating sustained plasma levels was greater for higher-dose, slow IV flecainide than for either intratracheal instillation (by 32%) or lower-dose, rapid IV infusion (by 88%). As a result, higher-dose, slow IV flecainide caused 58% (p < 0.03) and 48% (p < 0.006) greater increases in QRS complex duration and 61% and 96% (both, p < 0.02) greater reductions in contractility compared to intratracheal and lower-dose, rapid IV flecainide, respectively.

CONCLUSION

Lower-dose, rapid flecainide, delivered either intratracheally or IV, optimizes the plasma concentration profile for effective conversion of AF while minimizing adverse effects on QRS complex duration and LV contractility.

An electrocardiographic series of flecainide toxicity

Anti-arrhythmic drugs (AADs) uniquely affect the various electrolyte channels in the heart and can slow conduction, increase refractoriness, and/or decrease automaticity with the goal of preventing tachyarrhythmias. Due to these properties, these same drugs are by nature pro-arrhythmic. Vaughan-Williams classification Ic AADs belong to a class of medications that inhibit sodium channels, leading to decreased conduction velocity of myocytes and Purkinje fibers as well as to decreased automaticity of pacemaker cells. When present in toxic amounts, this leads to classic changes on the electrocardiogram (ECG) that are harbingers of potentially lethal arrhythmias. Presented is a clinical series of ECGs that occurred in a patient who presented with flecainide toxicity.

Long-term flecainide therapy in type 3 long QT syndrome

Aims

Type 3 long QT syndrome (LQT3) is caused by gain-of-function mutations in the cardiac sodium channel gene (SCN5A). Previous reports on the long-term use of sodium channel blockers in LQT3 are sparse. The objective of the current study was to evaluate the long-term safety and efficacy of flecainide therapy in patients with LQT3 who carry the D1790G SCN5A mutation.

Methods and results

The study population comprised 30 D1790G carriers who were treated with flecainide and followed for 1-215 months (mean 145 ± 54 months, median 140 months). The mean baseline (off-drug) QTc was 522 ± 45 ms, and shortened to 469 ± 36 ms with flecainide therapy, a mean decrease of 53 ms [10.1%] (P < 0.01). A QTc longer than 500 ms was evident in 53% of carriers at baseline, and only in 13% on flecainide. All carriers while being compliant with flecainide therapy had no cardiac events during an average follow up of 83 ± 73 months. Twenty carriers stopped flecainide after an average follow up of 40 ± 42 months without symptoms. Six of them (30%) had cardiac events 1-11 months after stopping flecainide. Flecainide induced the appearance of Brugada pattern in six carriers (20%, 5 males), was stopped in three and was not associated with arrhythmia. Sinus-node dysfunction was evident in six carriers (20%) and was fully corrected by flecainide in three.

Conclusions

These data suggest that long-term flecainide therapy is relatively safe and effective among LQT3 patients who carry the D1790G SCN5A mutation.

Evaluation of cardiac arrhythmic risks using a rabbit model of left ventricular systolic dysfunction

Patients with heart disease have a higher risk to develop cardiac arrhythmias, either spontaneously or drug-induced. In this study, we have used a rabbit model of myocardial infarction (MI) with severe left ventricular systolic dysfunction (LVSD) to study potential drug-induced cardiac risks with N-(piperidin-2-ylmethyl)-2,5-bis(2,2,2-trifluoroethoxy)benzamide (flecainide). Upon ligation of the left circumflex arteries, male New Zealand White rabbits developed a large MI and moderate or severe LVSD 7 weeks after surgery, in comparison to SHAM-operated animals. Subsequently, animals were exposed to escalating doses of flecainide (0.25-4 mg/kg) or solvent. Electrocardiograms (ECG) were recorded before surgery, 1 and 7 weeks after surgery and continuously during the drug protocol. The ECG biomarker iCEB (index of Cardio-Electrophysiological Balance = QT/QRS ratio) was calculated. During the ECG recording at week 1 and week 7 post MI, rabbits had no spontaneous cardiac arrhythmias. When rabbits were exposed to escalating doses of flecainide, 2 out of 5 rabbits with MI and moderate LVSD versus 0 out of 5 solvent-treated rabbits developed arrhythmias, such as ventricular tachycardia/ventricular fibrillation. These were preceded by a marked decrease of iCEB just before the onset (from 4.09 to 2.42 and from 5.56 to 2.25, respectively). Furthermore, 1 out of 5 MI rabbits with moderate LVSD and 1 out of 7 MI rabbits with severe LVSD developed total atrioventricular block after flecainide infusion and died. This rabbit model of MI and severe LVSD may be useful for preclinical evaluation of drug (similar mechanism as flecainide)-induced arrhythmic risks, which might be predicted by iCEB.

Predictors of sinus rhythm after electrical cardioversion of atrial fibrillation: results from a data mining project on the Flec-SL trial data set

Aims

Data mining is the computational process to obtain information from a data set and transform it for further use. Herein, through data mining with supportive statistical analyses, we identified and consolidated variables of the Flecainide Short-Long (Flec-SL-AFNET 3) trial dataset that are associated with the primary outcome of the trial, recurrence of persistent atrial fibrillation (AF) or death.

Methods and results

The 'Ranking Instances by Maximizing the Area under the ROC Curve' (RIMARC) algorithm was applied to build a classifier that can predict the primary outcome by using variables in the Flec-SL dataset. The primary outcome was time to persistent AF or death. The RIMARC algorithm calculated the predictive weights of each variable in the Flec-SL dataset for the primary outcome. Among the initial 21 parameters, 6 variables were identified by the RIMARC algorithm. In univariate Cox regression analysis of these variables, increased heart rate during AF and successful pharmacological conversion (PC) to sinus rhythm (SR) were found to be significant predictors. Multivariate Cox regression analysis revealed successful PC as the single relevant predictor of SR maintenance. The primary outcome risk was 3.14 times (95% CI:1.7-5.81) lower in those who had successful PC to SR than those who needed electrical cardioversion.

Conclusions

Pharmacological conversion of persistent AF with flecainide without the need for electrical cardioversion is a powerful and independent predictor of maintenance of SR. A strategy of flecainide pretreatment for 48 h prior to planned electrical cardioversion may be a useful planning of a strategy of long-term rhythm control.

Probing flecainide block of INa using human pluripotent stem cell-derived ventricular cardiomyocytes adapted to automated patch-clamping and 2D monolayers

Human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) are emerging tools for applications such as drug discovery and screening for pro-arrhythmogenicity and cardiotoxicity as leading causes for drug attrition. Understanding the electrophysiology (EP) of hPSC-CMs is essential but conventional manual patch-clamping is highly laborious and low-throughput. Here we adapted hPSC-CMs derived from two human embryonic stem cell (hESC) lines, HES2 and H7, for a 16-channel automated planar-recording approach for single-cell EP characterization. Automated current- and voltage-clamping, with an overall success rate of 55.0 ± 11.3%, indicated that 90% of hPSC-CMs displayed ventricular-like action potential (AP) and the ventricular cardiomyocytes (VCMs) derived from the two hESC lines expressed similar levels of I_Na, I_CaL, I_kr and I_f and similarly lacked I_to and I_K1. These well-characterized hPSC-VCMs could also be readily adapted for automated assays of pro-arrhythmic drug screening. As an example, we showed that flecainide (FLE) induced I_Na blockade, leftward steady-state inactivation shift, slowed recovery from inactivation in our hPSC-VCMs. Since single-cell EP assay is insufficient to predict drug-induced reentrant arrhythmias, hPSC-VCMs were further reassembled into 2D human ventricular cardiac monolayers (hvCMLs) for multi-cellular electrophysiological assessments. Indeed, FLE significantly slowed the conduction velocity while causing AP prolongation. Our RNA-seq data suggested that cell-cell interaction enhanced the maturity of hPSC-VCMs. Taken collectively, a combinatorial approach using single-cell EP and hvCMLs is needed to comprehensively assess drug-induced arrhythmogenicity.

Flecainide Toxicity: A Case Report and Systematic Review of its Electrocardiographic Patterns and Management

In the setting of flecainide toxicity, supraventricular tachycardia can manifest as a bizarre right or left bundle branch block, sometimes with a northwest axis, and can easily be mistaken for ventricular tachycardia leading to inappropriate therapy. We conducted a comprehensive literature review for cases of flecainide toxicity. We found 21 articles of flecainide toxicity in adult patients in which 22 ECG tracings were published. In patients with flecainide toxicity and QRS duration ≤ 200 ms, the ECGs were more likely to show RBBB, visible P waves (p = 0.03), and shorter QT (p = 0.02) and QTc intervals (p = 0.004). With QRS duration > 200 ms, the ECGs were more likely to show LBBB, loss of P waves, a northwest axis (p = 0.01), and longer QT and QTc intervals. Deaths were reported only in patients with QRS duration >200 ms, and the outcome of death or requirement for mechanical circulatory support was more prevalent in patients with a QRS duration > 200 ms [2/13 (15.4 %) vs. 6/10 (60 %), p = 0.04]. In patients with access to the medication, flecainide toxicity should be suspected with: (1) broad QRS, (2) RBBB morphology with QRS ≤ 200 ms; RBBB or LBBB morphology with QRS ≥ 200 ms (3) HR out of proportion to the degree of hemodynamic instability. The duration of the QRS interval is prognostic, with mortality and the requirement for mechanical circulatory support being more common in patients with a QRS > 200 ms.

Effect of flecainide on atrial fibrillatory rate in a large animal model with induced atrial fibrillation

Background

Atrial fibrillatory cycle length has been considered one of the indices of atrial electrical remodelling during atrial fibrillation (AF), which can be assessed from surface ECG by computer-assisted calculation of atrial fibrillatory rate (AFR). Horses have been suggested as a bona fide model for AF studies since horses too, develop lone AF, however data on AF characteristics in horses are extremely sparse and non-invasive characterization of AF complexity using surface ECG processing has not been reported.

Aim

The aim was to study characteristics of induced AF and its modification by flecainide.

Methods

The study group consisted on 3 horses with spontaneous persistent AF and 13 with pace-induced AF. Seven horses were treated with saline (control) and eight with flecainide (2 mg/kg). ECGs were analysed using spatiotemporal cancellation of QRST complexes and calculation of AFR from the residual atrial signal.

Results

At AF onset, AFR was 295 ± 52 fibrillations per minute (fpm) in the horses with induced AF treated with flecainide, 269 ± 36 fpm in the control group (ns), and 364 ± 26 fpm in the horses with spontaneous persistent AF (P < 0.05 compared to the control group). Flecainide caused a decrease in AFR in all animals and restored sinus rhythm in the animals with induced AF. In the control animals, AFR increased from 269 ± 36 fpm to a plateau of 313 ± 14 fpm before decreasing to 288 ± 28 fpm during the last 10% of the AF episodes preceding spontaneous conversion (P < 0.05).

Conclusion

AFR in horses with induced AF resembles AFR in humans with paroxysmal AF. Flecainide caused a rapid decrease in AFR in all horses, further supporting the method to be a non-invasive technique to study the effect of antiarrhythmic compounds.

Initiation and outcomes with Class Ic antiarrhythmic drug therapy

BACKGROUND

Expert opinion recommends performing exercise testing with initiation of Class Ic antiarrhythmic medication.

OBJECTIVE

To evaluate the rate and reason for discontinuation of Ic agent within the first year of follow up, with particular attention to rate of proarrhythmia and the value of routine treadmill testing.

METHODS

This is a single center retrospective cohort study including consecutive patients with atrial arrhythmias who were initiated on a Class Ic agent from 2011 to 2016. Data was collated from chart review and pharmacy database.

RESULTS

The study population included 300 patients (55% male, mean age 61; mean ejection fraction, 56%) started on flecainide (n = 153; 51%) and propafenone (n = 147; 49%). Drug initiation was completed while hospitalized on telemetry and the staff electrophysiologists directed dosing. There was one proarrhythmic event during initiation (0.3%). The primary reason for not being discharged on Ic agent was due to detection of proarrhythmia (n = 15) or ischemia (n = 1) with treadmill testing (5.3%). Exercise testing was the single significant variable to affect the decision to discontinue Ic drug, p < 0.0001 (95% CI: 1.89-6.08%). During follow up, the primary reason for discontinuation of Ic agent was lack of efficacy, 32%.

CONCLUSIONS

With proper screening, initiation of Class Ic agent is associated with very low rate of proarrhythmia. Treadmill testing is of incremental value and should be completed in all patients after loading Class Ic antiarrhythmic.

The Safety and Effectiveness of Flecainide in Children in the Current Era

This retrospective study sought to determine the safety and effectiveness of flecainide in children with normal hearts and those with congenital heart disease (CHD) or cardiomyopathy (CMO). Baseline and follow-up data at two pediatric cardiology sites were queried (2000-2015); a total of 175 patients (20 with CHD and two with CMO) receiving flecainide were assessed. When comparing patients with CHD to those with normal hearts, patients with CHD were younger at diagnosis (median age 19 days; IQR 3-157.5 days vs normal heart patients median age 21 days; IQR 7-172 days, p = 0.4) and severe cardiac dysfunction was more prevalent (30% in CHD patients vs 8% in normal heart patients, p = 0.009). Treatment duration did not differ between the two groups (CHD patients median duration 52 weeks; IQR 27-91.5 weeks vs normal heart patients median duration 55 weeks; IQR 32-156 weeks, p = 0.5). Cardiac dysfunction resulting in flecainide discontinuation occurred in two patients (1%), one with CHD and one without. Three patients experienced proarrhythmia (2%) and there were no cardiac arrests during follow-up. There was one death in this cohort in a patient with severe CHD and an RSV infection (<1%). Arrhythmia control did not differ between the groups (90% in CHD patients vs 77% in normal heart patients, p = 0.2). Flecainide was well tolerated in this cohort, with fewer than 3% discontinuing medication due to flecainide-associated adverse events. Contrary to adult studies, there was no difference in the incidence of adverse events between patients with normal hearts and patients with CHD. Flecainide is a safe and effective antiarrhythmic medication, even for children with underlying CHD.