Hemodynamic effects of intravenous flecainide relative to the level of ventricular function in patients with coronary artery disease

Wide Spectrum of Flecainide Toxicity: A Case Report and Literature Review

Flecainide toxicity is a rare but serious condition that can present with a wide range of clinical symptoms. We report the case of a 79-year-old female with paroxysmal atrial fibrillation on flecainide therapy who developed altered mental status, visual hallucinations, and bradycardia. Laboratory results revealed an acute kidney injury, which contributed to elevated flecainide levels. Discontinuation of flecainide led to a rapid resolution of symptoms and normalization of ECG findings. This case underscores the critical need for careful monitoring of renal function and potential drug interactions in patients receiving flecainide to prevent toxicity, highlighting the wide range of flecainide toxicity, including rare manifestations such as encephalopathy and visual hallucinations.

The Feasibility and Safety of Flecainide Use Among Patients With Varying Degrees of Coronary Disease

BACKGROUND

Class 1C antiarrhythmic agents are effective for treating atrial tachyarrhythmias, but their use is restricted in patients with coronary artery disease (CAD). Data on the safety of the use of 1C agents in patients with CAD in the absence of recent acute coronary syndromes are lacking.

OBJECTIVE

This study sought to evaluate the safety and feasibility of treatment with 1C agents in patients with varying degrees of CAD in a large serial, real-world cohort.

METHODS

We retrospectively identified all patients at our institution from January 2005 to February 2021 on a 1C agent (n = 3,445) and those on sotalol or dofetilide (n = 2,216) as controls, excluding those with a prior history of ventricular tachycardia, implantable cardioverter-defibrillator placement, or nonrevascularized myocardial infarction. Baseline clinical characteristics included degree of CAD (categorized as none, nonobstructive, or obstructive), other comorbid illness, and medication use. Clinical outcomes, including survival, were ascertained. We performed Cox regression analysis to evaluate the effect of 1C use on event-free survival across varying degrees of CAD.

RESULTS

After adjustment for baseline characteristics, there was an independent association between 1C use and improved mortality. However, there was an interaction between 1C use and degree of CAD (compared to sotalol) demonstrating poorer event-free survival among those with obstructive coronary disease (HR: 3.80; 95% CI: 1.67-8.67; P = 0.002).

CONCLUSIONS

Among select patients with nonobstructive CAD and without a history of ventricular tachycardia, 1C agents are not associated with increased mortality. Therefore, these agents may be an option for some patients in whom they are frequently restricted. Further prospective studies are warranted.

Cardioversion of recent-onset atrial fibrillation using intravenous antiarrhythmics: A European perspective

Pharmacological cardioversion using intravenous antiarrhythmic agents is commonly indicated in symptomatic patients with recent-onset atrial fibrillation (AF). Except in hemodynamically unstable patients who require emergency direct current electrical cardioversion, for the majority of hemodynamically stable patients, pharmacological cardioversion represents a valid option and requires the clinician to be familiar with the properties and use of antiarrhythmic agents. The main characteristics of selected intravenous antiarrhythmic agents for conversion of recent-onset AF, the reported success rates, and possible adverse events are discussed. Among intravenous antiarrhythmics, flecainide, propafenone, amiodarone, sotalol, dofetilide, ibutilide, and vernakalant are commonly used. Antazoline, an old antihistaminic agent with antiarrhythmic properties was also reported to give encouraging results in Poland. Intravenous flecainide and propafenone are the only Class I agents still recommended by recent guidelines. Intravenous new Class III agents as dofetilide and ibutilide have high and rapid efficacy in converting AF to sinus rhythm but require strict surveillance with electrocardiogram (ECG) monitoring during and after intravenous administration because of the potential risk of QT prolongation and Torsades de Pointes, which can be prevented and properly managed. Vernakalant, a partial atrial selective was shown to have a high success rate and to be safe in real-life use.

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.

Flecainide How and When: A Practical Guide in Supraventricular Arrhythmias

Transcatheter ablation was increasingly and successfully used to treat symptomatic drug refractory patients affected by supraventricular arrhythmias. Antiarrhythmic drug treatment still plays a major role in patient management, alone or combined with non-pharmacological therapies. Flecainide is an IC antiarrhythmic drug approved in 1984 from the Food and Drug Administration for the suppression of sustained ventricular tachycardia and later for acute cardioversion of atrial fibrillation and for sinus rhythm maintenance. Currently, flecainide is mostly used for sinus rhythm maintenance in atrial fibrillation (AF) patients without structural cardiomyopathy although recent studies enrolling different patient populations have demonstrated a good effectiveness and safety profile. How should we interpret the results of the CAST after the latest evidence? Is it possible to expand the indications of flecainide, and therefore, its use? This review aims to highlight the main characteristics of flecainide, as well as its optimal clinical use, delineating drug indications and contraindications and appropriate monitoring, based on the most recent evidence.

Use of Flecainide for the Treatment of Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia and is associated with substantial morbidity and impairment of quality of life. Restoration and maintenance of normal sinus rhythm is a desirable goal for many patients with AF; however, this strategy is limited by the relatively small number of antiarrhythmic drugs (AADs) available for AF rhythm control. Although it is recommended in current medical guidelines as first-line therapy for patients without structural heart disease, the use of flecainide has been curtailed since the completion of the Cardiac Arrhythmia Suppression Trial. In clinical trials and real-world use, flecainide has proven to be more effective than other AADs for the acute termination of recent onset AF. Flecainide is also moderately effective and, with the exception of amiodarone, equivalent to other AADs for the chronic suppression of paroxysmal and persistent AF. In patients without structural heart disease, flecainide has been demonstrated to be safe and well tolerated relative to other AADs. Despite this favorable profile, flecainide is underutilized, likely due to a perceived risk of ventricular proarrhythmia, a concern that has not been borne out in patients without underlying structural heart disease. Guidelines for administration and use of flecainide are summarized in this review.

n-3 PUFA and caloric restriction diet alters lipidomic profiles in obese men with metabolic syndrome: a preliminary open study

PURPOSE

For people with metabolic syndrome (MetS), altering the macronutrient composition of their diets might ameliorate metabolic abnormalities. The common method of clinical assessment only measures total lipid concentrations but ignores the individual species that contribute to these total concentrations. Thus, to predict the amelioration of MetS following caloric restriction (CR) and the intake of fish oil, we used lipidomics to investigate changes in plasma lipids and identify potential lipid metabolites.

METHODS

Lipidomics was performed using ultra-high-performance liquid chromatography-tandem mass spectrometry on plasma samples from a clinical trial conducted over 12 weeks. Subjects were randomized into two groups: CR (n = 12) and CR with fish oil (CRF, n = 9). Anthropometric and clinical parameters were measured and correlated with plasma lipidomics data.

RESULTS

Compared with baseline, significant differences were observed in body weight, waist circumference, blood pressure and interleukin-6 in both groups, but triglyceride (TG) levels significantly decreased in only the CRF group (all p < 0.05). A total of 138 lipid species were identified. Levels of species containing long-chain polyunsaturated fatty acids were significantly elevated-greater than twofold-following fish oil intake, these included TG (60:9) and phosphatidylcholine (p40:6) (all q < 0.05). TG (60:9) tended to correlate negatively with body weight, body mass index, blood pressure, and HbA1c following fish oil intake.

CONCLUSION

CR and fish oil can ameliorate MetS features, including anthropometric parameters, blood pressure, and blood lipid concentrations. The levels of particular lipid species such as TG-containing docosapentaenoic acid were elevated post-intervention and negatively associated with MetS features. TG (60:9) may be proposed as a lipid metabolite to predict amelioration in MetS following the intake of CR and fish oil.

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.

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.

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.

Flecainide: Current status and perspectives in arrhythmia management

Flecainide acetate is a class IC antiarrhythmic agent and its clinical efficacy has been confirmed by the results of several clinical trials. Nowadays, flecainide is recommended as one of the first line therapies for pharmacological conversion as well as maintenance of sinus rhythm in patients with atrial fibrillation and/or supraventricular tachycardias. Based on the Cardiac Arrhythmia Suppression Trial study results, flecainide is not recommended in patients with structural heart disease due to high proarrhythmic risk. Recent data support the role of flecainide in preventing ventricular tachyarrhythmias in patients with catecholaminergic polymorphic ventricular tachycardia associated both with ryanodine receptor and calsequestrin mutations. We herein review the current clinical data related to flecainide use in clinical practice and some concerns about its role in the management of patients with coronary artery disease.

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.

Twenty-five years in the making: flecainide is safe and effective for the management of atrial fibrillation

Atrial fibrillation (AF) is the most common arrhythmia in clinical practise and its prevalence is increasing. Over the last 25 years, flecainide has been used extensively worldwide, and its capacity to reduce AF symptoms and provide long-term restoration of sinus rhythm (SR) has been well documented. The increased mortality seen in patients treated with flecainide in the Cardiac Arrhythmia Suppression Trial (CAST) study, published in 1991, still deters many clinicians from using flecainide, denying many new AF patients a valuable treatment option. There is now a body of evidence that clearly demonstrates that flecainide has a favourable safety profile in AF patients without significant left ventricular disease or coronary heart disease. As a result of this evidence, flecainide is now recommended as one of the first-line treatment options for restoring and maintaining SR in patients with AF under current treatment guidelines. The objective of this article is to review the literature pertaining to the pharmacological characteristics, safety and efficacy of flecainide, and to place this drug in the context of current therapeutic management strategies for AF.

Flecainide augments muscle sympathetic nerve activity in humans

The Cardiac Arrhythmia Suppression Trial has shown that treatment with flecainide is associated with an increased incidence of cardiac death in patients following myocardial infarction. It is believed that there is a complex mechanism involving an interaction between flecainide, sympathetic activation, and acute ischemia that is responsible for the increased risk of sudden death. The purpose of this study was to determine the effects of flecainide on muscle sympathetic nerve activity (MSNA) in humans. We measured MSNA using microneurography and cardiac output using the dye dilution method in 30 healthy individuals. Measurements were made at rest and after the oral administration of flecainide (200mg, n=12) or placebo (n=9), or intravenous administration of propranolol (0.2 mg/kg, n=9). Flecainide significantly increased heart rate and decreased the cardiac index (both p<0.01). Flecainide increased the burst rate from 16.7 +/- 3.5 to 23.3 +/- 4.1 bursts/min and the burst incidence from 26.6 +/- 5.1 to 34.7 +/ -5.6bursts/100 heartbeats (both p<0.01). For all of the hemodynamic parameters except heart rate, the effects of propranolol were similar to those of flecainide. Propranolol also increased the burst rate by 52 +/- 34% and the burst incidence by 106 +/- 39%. These results suggest that flecainide suppresses myocardial contractility and produces reflex-mediated increases in sympathetic nerve firing in humans.

Refractory Heart Failure: A Therapeutic Approach

Optimal “triple therapy” for patients with chronic congestive heart failure (CHF) includes diuretics, digoxin, and either angiotensin-converting enzyme inhibitors or hydralazine plus nitrates. Refractory CHF is defined as symptoms of CHF at rest or repeated exacerbations of CHF despite “optimal” triple-drug therapy. Most patients with refractory CHF require hemodynamic monitoring and treatment in the intensive care unit. If easily reversible causes of refractory CHF cannot be identified, then more aggressive medical and surgical interventions are necessary. The primary goal of intervention is to improve hemodynamics to palliate CHF symptoms and signs (i.e., dyspnea, fatigue, edema). Secondary goals include improved vital organ and tissue perfusion, discharge from the intensive care unit, and, in appropriate patients, bridge to cardiac transplantation. Medical interventions include inotropic resuscitation (e.g., adrenergic agents, phosphodiesterase inhibitors, allied nonglycoside inodilators), load resuscitation (e.g., afterload and preload reduction with nitroprusside or nitroglycerin; preload reduction with diuretics and diuretic facilitators, such as dopaminergic agents or ultrafiltration), and electrical resuscitation (e.g., prevention of sudden death, correction of new or rapid atrial fibrillation, or dual chamber pacing in the setting of relative prolongation of the PR interval and diastolic mitral/tricuspid regurgitation). Surgical interventions are temporizing (e.g., intra-aortic balloon pump and other mechanical assist devices) or definitive (e.g., coronary artery revascularization, valvular surgery, and cardiac transplantation). Although these interventions may improve immediate survival in the short term, only coronary artery revascularization and cardiac transplantation have been shown to improve long-term survival.

Sudden death in patients with congestive heart failure: future directions

Sudden, unexpected cardiac death continues to be a major clinical problem in patients with congestive heat failure. This review summarizes the current state of knowledge regarding the identification and management of these patients. The roles of ambulatory ECG monitoring, electrophysiological testing, signal-averaged ECG, and other methods of predicting increased risk of sudden death are discussed. The modes of sudden cardiac death and the potential mechanisms of ventricular arrhythmias in congestive heart failure are reviewed. Current therapeutic options including antiarrhythmic drugs, neurohormonal blockade, and automatic implantable cardioverter defibrillators are discussed. Finally, future directions and ongoing clinical investigations of the management of these complex patients are considered.

Arrhythmias in patients with CHF. Should they be treated?

Ventricular arrhythmias are a major cause of death in patients with congestive heart failure. Dr Ellenbogen and his associates discuss the current thinking, based on recent studies, concerning use of antiarrhythmic agents to prevent sudden cardiac death in these patients. As they point out, the proper antiarrhythmic therapy may be crucial to long-term survival.

Plasma concentration of atrial natriuretic peptide in spontaneous atrioventricular re-entrant tachycardias of childhood

Plasma atrial natriuretic peptide was measured in 13 children between the ages of 1 week and 2 years 9 months during atrioventricular re-entrant tachycardia and 15 minutes after the restoration of sinus rhythm. There was a significant decline in atrial natriuretic peptide during sinus rhythm. Plasma concentrations of the peptide were significantly higher during tachycardia in seven infants under 1 year than in the six older children. The heart rates and the duration of tachycardia were not significantly different in the two age groups. Cardiac failure was present in five of seven children under 18 weeks of age during tachycardia but in none of the older children. The plasma concentration of atrial natriuretic peptide did not significantly correlate with duration of tachycardia or heart rate. If tachycardia occurs in young infants the low functional reserve capacity of the developing heart leads to cardiac failure more frequently and it is likely that this was the cause of the significantly higher plasma concentration of atrial natriuretic peptide in the younger children.

Are antiarrhythmic drugs safe?

The indications for antiarrhythmic therapy are far from clearly defined and the choice of treatment is usually based on empiric strategies. Antiarrhythmic agents can have serious side effects. Systemic adverse effects are usually use-related and reversible with withdrawal of the drug. Impairment of left ventricular function is considerable in patients with heart failure. The most important, life-threatening side effect of antiarrhythmic drugs is their proarrhythmic tendency which gives rise to certain concern about their clinical use. Aggravation of arrhythmia often occurs without symptoms, goes unrecognized by the patient, and is exposed only by monitoring, exercise testing, or invasive electrophysiological testing. Patient monitoring with electrolyte measurement, Holter recording, and electrophysiological reassessment can reveal or reduce the proarrhythmic risk but cannot eliminate the problem completely. The institution of antiarrhythmic therapy should be considered in highly symptomatic or life-threatening arrhythmias after careful consideration of the benefit-risk ratio.

Antiarrhythmic drug therapy for congestive heart failure with focus on moricizine

Many patients who have serious ventricular arrhythmia requiring antiarrhythmic drug therapy have congestive heart failure (CHF). However, the pharmacokinetic and pharmacodynamic properties of the antiarrhythmic drugs are altered in the presence of CHF. It has been reported that some adverse effects, primarily aggravation of arrhythmia and CHF occur more frequently in patients with a history of left ventricular (LV) dysfunction. Moreover, antiarrhythmic drugs are less effective in patients with a history of CHF and a reduced LV ejection fraction (LVEF). Moricizine, a new antiarrhythmic drug, has been undergoing clinical trials for over 13 years in the United States. The data base involving 1,072 patients was analyzed to establish the effect of this agent in patients with CHF. The presence of CHF does not alter the absorption, half-life and clearance of moricizine. The incidence of CHF exacerbation definitely related to moricizine was low (2%) and occurred primarily in patients with a history of CHF. Aggravation of arrhythmia and conduction abnormalities also occurred more often in patients with prior CHF. However, the incidence of all other adverse effects involving other organ systems was the same in patients with and without CHF and was also unrelated to the baseline LVEF. The effect of moricizine for suppressing spontaneously occurring ventricular ectopy was also similar in patients with and without CHF and was independent of LVEF. However, the drug is less effective in preventing sustained ventricular arrhythmia in patients with CHF.

Transcatheter radiofrequency ablation of atrial tissue using a suction catheter

Closed chest ablative technique that avoid barotrauma would be attractive for ablation at thin walled cardiac structures, such as the atrial free wall or coronary sinus. Transcatheter radiofrequency (RF) currents produce tissue necrosis the size of which is dependent on the contact between the tissue and the electrode. In order to assess the effects of transvenous RF ablation of atrial free wall using a suction electrode catheter, we delivered in ten dogs, one single unmodulated RF pulse 1.2 MHz, in a unipolar mode, through the distal electrode of a lumen catheter (USCI 8F) (USCI, Billerica, MA USA) located in the right appendage. During the pulse an 80 KPa vacuum depression was applied to the lumen of the catheter. Each pulse had a 10 seconds duration and the mean delivered power was 4.3 +/- 1.4 W. Aortic pressure and electrocardiogram were monitored during the procedure. A right atrial electrophysiological study was performed at the ablated site, at control, after suction application and after RF pulse delivery. The animals were sacrificed after 14 or 21 days. Atrial pacing threshold values decreased after suction application in comparison to control values after the pulse (0.42 +/- 0.06 vs 0.60 +/- 0.23 mA, P less than O.05) but increased after the pulse delivery (2.60 +/- 1.85 mA, P less than 0.01). In contrast, the atrial effective refractory period did not significantly change after suction, nor after RF pulse delivery. Aortic pressure remained unchanged throughout the procedure. Complex arrhythmias were not observed during or after RF pulse delivery. One dog died suddenly at the first day after ablation, but this death was most probably unrelated to RF ablation. Anatomic lesions had a length of 8.8 +/- 3.3 mm, a width of 4.6 +/- 2.5 mm and a depth of 3.6 +/- 1.1 mm. They were transmural in nine of the ten dogs but without atrial wall perforation in any case. Lesions suggesting tissue volatilization were present in four dogs. These results demonstrate that low energy RF currents delivered with a suction electrode catheter can produce transmural necrosis of free wall, without risk of perforation. Such ablative technique would be of interest for ablation of right sided accessory pathways or atrial ectopic foci. Further experimental data are required in order to define the optimal energy level required to avoid tissue volatilization.

Long term inotropic effects of flecainide and propafenone

This study was undertaken to evaluate the effect of flecainie (Fle) and propafenone (Pro) on rest and exercise myocardial contractility after prolonged oral administration. Standardized, fully automated, gated radionuclide angiograms at rest and during maximum exercise were performed single blinded and prospectively in 19 patients before and after oral treatment with either 150 mg b.i.d. of Fle or 150 mg t.i.d. of Pro. The left ventricular ejection fraction (EF%) as a hemodynamic indicator presented as follows: (Table: see text) In general, there was no significant effect of either drug on resting ventricular function. In only one patient of the Fle group with decreased baseline function did the left ventricular EF fall from 40% to 29%. During exercise, ventricular performance showed deterioration in the Pro group, but, interestingly, improvement in the Fle group. As a result of these opposite changes, the effect of the two drugs on the exercise response of ventricular function was significantly different (P less than 0.05). This study thus gives first evidence that no significant cardiodepressive effects are to be expected after prolonged application of Fle or Pro in normal hearts. There might even be a mild beneficial effect on exercise performance after Fle.

Mortality in heart failure: clinical variables of prognostic value

One hundred and fifty two patients with chronic heart failure caused primarily by left ventricular dysfunction were followed prospectively in an open study for a mean period of 21 months. The effects of several clinical variables on subsequent outcome were examined, including the effects of treatment, which was determined by the clinician caring for the patient and was not randomly allocated. In order of importance, frequent ventricular extrasystoles, non-treatment with amiodarone, low mean arterial pressure, and a diagnosis of coronary artery disease were associated with a poor prognosis, with each of these variables providing extra predictive information independently of the others. Initial serum potassium concentration and treadmill exercise time also carried further weak but independent prognostic information. Neither treatment with angiotensin converting enzyme inhibitors nor digoxin appeared to affect outcome. Left ventricular function (as reflected by M mode echocardiography) and the dose of diuretic also failed to predict outcome. There did, however, appear to be a reduction in the frequency of sudden death when angiotension converting enzyme inhibitors were given. Further studies are required to confirm the adverse prognostic significance of ventricular arrhythmias in patients with heart failure and the possible benefit associated with amiodarone treatment.

Pharmacokinetics and pharmacodynamics of antiarrhythmic agents in patients with congestive heart failure

Changes in the pharmacokinetics of antiarrhythmic agents may be anticipated in patients with congestive heart failure (CHF), although the magnitude or direction of change is not always predictable. Factors complicating antiarrhythmic therapy in patients with CHF include both physiologic changes resulting from the disease state and unwanted effects of drug therapy for CHF. The volume of distribution is often significantly decreased (by as much as 50%) and loading doses should be reduced proportionately. Decreased blood flow to the liver and kidneys and decreased hepatic drug-metabolizing activity serve to diminish drug clearance. In some cases, simultaneous decreases in volume of distribution and clearance may result in little, if any, change in elimination half-life, despite higher plasma concentrations. Conversely, the elimination half-life of antiarrhythmic agents may be doubled in patients with CHF, necessitating a reduction in dosage. In the latter case, the time needed to reach steady state is lengthened, so that premature escalation of dosage may lead to excessive drug accumulation. In terms of their pharmacodynamics, most antiarrhythmic agents have a degree of negative inotropic effect at some concentration, and patients with reduced myocardial reserve are especially vulnerable to these effects. Some of the newer agents (such as tocainide, mexiletine, and encainide) appear to cause only minimal myocardial depression. Potential complications during therapy with all antiarrhythmic agents that are of special concern in patients with CHF include diuretic-induced hypokalemia, proarrhythmia, and possible interactions with cardiac glycosides and other drugs. Therapy for patients with CHF should be initiated with low doses of the agent selected, and the dosage carefully titrated while the patient is monitored, to confirm both efficacy and the absence of adverse effects. During subsequent outpatient therapy the patient should be carefully observed for sign of unexpected reactions, toxicity, or electrolyte imbalance.

Clinical, haemodynamic, and antiarrhythmic effects of long term treatment with amiodarone of patients in heart failure

Twenty two patients with heart failure were studied in a double blind crossover trial to compare amiodarone (200 mg/day) with placebo. Each agent was given for three months. Extrasystoles and complex ventricular arrhythmias were common during ambulatory electrocardiographic monitoring and during exercise testing at entry to the study. Breathlessness and tiredness as assessed by visual analogue scores and duration of treadmill exercise did not become worse during amiodarone treatment. During the placebo and amiodarone phases of the study left ventricular ejection fraction and cardiac index determined by first pass radionuclide ventriculography were similar, both at rest and during upright bicycle exercise. Exercise induced ventricular tachycardia was abolished and simple and complex ventricular arrhythmias observed on 24 hour ambulatory monitoring were greatly diminished during amiodarone treatment. Three patients died, all suddenly, during the placebo phase. In two patients amiodarone was withdrawn after a further myocardial infarction in one and a worsening of symptoms of ventricular arrhythmia in the other. In contrast with other antiarrhythmic agents amiodarone is effective in suppressing ventricular arrhythmias in heart failure without causing adverse haemodynamic effects. Because frequent ventricular arrhythmias are known to be associated with a poor prognosis in heart failure, these data suggest that amiodarone may improve the poor prognosis in patients with heart failure.

Effects of congestive heart failure on the pharmacokinetics and pharmacodynamics of antiarrhythmic agents

Changes in the pharmacokinetics of antiarrhythmic agents should be expected in patients with congestive heart failure (CHF). The direction of the changes, however, is not always predictable. The volume of distribution is often decreased by as much as 40%, and loading doses should, therefore, be appropriately reduced. Drug clearance may also be diminished due to decreased blood flow to the liver and kidneys, as well as decreased hepatic drug-metabolizing activity. Infusion rates should similarly be lowered to avoid toxicity. However, decreases in both volume of distribution and clearance may result in little, if any, change in elimination half-life, despite higher plasma concentrations. On the other hand, the elimination half-life of antiarrhythmic agents that have a large volume of distribution and are highly cleared by the liver may be twice as long in patients with CHF compared with normal subjects. Thus, the total daily dose of drug should also be lower in these patients. In addition, the time necessary to reach steady state is longer, so that premature dose escalation may lead to excessive drug accumulation. In terms of their pharmacodynamic effects, all antiarrhythmic agents have the potential to manifest a degree of negative inotropy, which must be anticipated as a possible side effect in patients with CHF. Some of the newer agents, such as tocainide and encainide, appear to cause only minimal myocardial depression. Other potential complications of all antiarrhythmic therapy include proarrhythmia and possible drug interactions with digitalis and diuretics.

Flecainide: a new class Ic antidysrhythmic

Flecainide acetate is a new orally active antidysrhythmic agent classified in the Ic category. Flecainide is effective in suppressing 88 to 100 percent of abnormal cardiac rhythms in the form of complex ventricular dysrhythmias, including couplets, ventricular tachycardia, reentrant junctional tachycardia, and Wolff-Parkinson-White syndrome. Flecainide appears to have a greater effect on conduction than on repolarization and only minimal effects on hemodynamic parameters. Flecainide is rapidly and completely absorbed after oral administration and has a 13-hour elimination half-life, allowing for twice-daily dosing regimens. Flecainide is generally well tolerated, with dizziness, blurred vision, nausea, and headache the most common side effects. Flecainide has been shown to be superior to quinidine and disopyramide in suppressing ventricular ectopic activity and may be considered a first-line oral agent for this indication. It is believe that flecainide has enough therapeutic advantages to be added to drug formularies.

Flecainide: a new prototype antiarrhythmic agent

Flecainide acetate is the first class IC antiarrhythmic agent marketed in the United States. In vitro, animal and human studies have shown that the drug markedly prolongs conduction and has minimal effect on repolarization. Efficacy trials have shown flecainide to be effective in a wide range of ventricular and selected atrial arrhythmias. The drug is generally well tolerated, although minor adverse effects are common. These generally are related to the central nervous system and respond to a reduction in dosage. Like other antiarrhythmic agents, flecainide may demonstrate proarrhythmic effects. It is excreted in the urine as the parent compound and inactive metabolites. The elimination half-life ranges from 12-27 hours in patients with normal renal function, allowing convenient dosing regimens of 100-200 mg twice daily in most patients. Flecainide has the potential for widespread use.