Flecainide in quinidine-resistant atrial fibrillation

Flecainide-induced Increase in QRS Duration and Proarrhythmia during Exercise

In patients taking flecainide, exercise-induced arrhythmias are believed to be related to QRS widening at rest and during exercise. Our aim was to determine, retrospectively, predictive factors of flecainide-induced (a) QRS widening at rest and during exercise, and (b) proarrhythmia (PA) during exercise. Flecainide was administered to 119 patients for atrial and/or ventricular arrhythmias who performed a maximal treadmill test. A total of 63 patients had a normal heart (defined by the absence of structural heart disease and an ejection fraction ≥ 55% by echocardiography and/or cardiac catheterisation), 26 had coronaropathy, 18 valvulopathy and 3 had both, and 7 had dilated and 2 hypertrophic cardiomyopathy. The mean dosage of flecainide was 190 or 200 ± 10 mg/day. Previous myocardial infarction (MI) was a predictive variable of flecainide-induced QRS widening at rest (p = 0.04). During exercise, the risk factors of QRS widening were previous MI (p = 0.008), angina without previous MI (p = 0.009), structural heart disease (p = 0.001) and a bundle branch block at rest (p = 0.01). PA on exercise occurred in 7 patients. Structural heart disease (p = 0.04) and an impaired left ventricular ejection fraction (LVEF) [p = 0.02] were predictive variables of PA. All patients with left ventricular dysfunction and PA had a QRS widening with flecainide at rest ≥ 25%. The risk factors of QRS widening at rest and during exercise with flecainide were distinct from those of PA on exercise. In patients with an impaired LVEF, a flecainide-induced QRS widening of 25% at rest was the threshold value beyond which there was a high risk of PA during exercise. This study was retrospective and not a double-blind trial, therefore the results need to be corroborated in a prospectively designed trial.

Impact of informed consent requirements on cardiac arrest research in the United States: exception from consent or from research?

INTRODUCTION

Research in patients with life-threatening illness such as cardiac arrest is challenging since they can not consent. The Food and Drug Administration addressed research under emergency conditions by publishing new criteria for exception from informed consent in 1996. We systematically reviewed randomized trials over a 10-year period to assess the impact of these regulations.

METHODS

Case-control study of published trials for cardiac arrest (cases) and atrial fibrillation (controls.) Studies were identified by using structured searches of MEDLINE and EMBASE from 1992 to 2002. Included were studies using random allocation in humans with cardiac arrest or atrial fibrillation prior to enrollment. Excluded were duplicate publications. Number of American trials, foreign trials and proportion of trials of American origin were compared by using regression analysis. Changes in cardiac arrest versus atrial fibrillation trials were calculated as risk differences.

RESULTS

Of 4982 identified cardiac arrest studies, 57 (1.1%) were randomized trials. The number of American cardiac arrest trials decreased by 15% (95% CI: 8, 22%) annually (P = 0.05). The proportion of cardiac arrest trials of American origin decreased by 16% (95% CI: 10, 22%) annually (P = 0.006). Of 5596 identified atrial fibrillation studies, 197 trials (3.5%) were randomized trials. The risk difference between cardiac arrest versus atrial fibrillation trials being of American origin decreased significantly (annual difference -5.8% (95% CI: -10, -0.1%), P = 0.03).

INTERPRETATION

Fewer American cardiac arrest trials were published during the last decade, when federal consent requirements changed. Regulatory requirements for clinical trials may inhibit improvements in care and threaten public health.

Syncope in patients with atrial flutter during treatment with class Ic antiarrhythmic drugs

We describe 2 atrial flutter (AFL) patients with syncope during treatment with class Ic antiarrhythmic drugs. During the syncope, 1:1 atrioventricular (AV) conduction during AFL preceded a wide QRS tachycardia. The class Ic drugs, flecainide and pilsicainide, slowed the atrial rate, resulting in AFL with 1:1 AV conduction, and the width of the QRS complexes became wider during the tachycardia. Syncope was abolished after successful radiofrequency catheter ablation of the AFL. These potential proarrhythmic effects of the class Ic drugs should be taken into account in AFL patients, and concomitant use of beta-blocking agents would be critical to prevent proarrhythmias.

Optimal management with Class I and Class III antiarrhythmic drugs should be done in the outpatient setting: protagonist

It has been suggested that patients be admitted for the initiation of Class I and Class III antiarrhythmic drugs to avoid serious proarrhythmic consequences. The most clinically significant proarrhythmic response to Class IC agents is likely due to an interaction with acute ischemia, and hospitalization for initiation of drug therapy has little predictive or preventive value. Amiodarone has a low risk of proarrhythmia, and any proarrhythmic reactions are generally delayed. Class IA and Class III antiarrhythmic drugs cause acquired long QT syndrome arrhythmias, which can occur soon after initiation of therapy; however, only about half of the arrhythmic events occur within 3 days of initiation of therapy. It could be argued that all patients should be hospitalized to begin Class IA or Class III drugs; however, this approach has a low yield and is extremely expensive. An alternative is to use Class IA and Class III drugs for patients at low risk of torsades de pointes (e.g., males without heart failure, ventricular tachyarrhythmias, or active coronary disease), in whom hospitalization for drug initiation is not warranted. Higher risk patients are probably better treated with other agents, such as Class IC drugs or amiodarone for women without organic heart disease and amiodarone for patients with heart failure, a history of ventricular tachycardia, or active coronary disease. When a Class IA or Class III drug is required for patient with an increased risk of torsades de pointes, hospital admission for drug initiation may be indicated.

Selecting an antiarrhythmic agent for atrial fibrillation should be a patient-specific, data-driven decision

Selecting an antiarrhythmic agent for atrial fibrillation (AF) should be a patient-specific decision. When possible, it should be based on sound rationale and available clinical data. This article details many of the thought processes that must go into this decision process and offers some suggested algorithmic starting points based on these considerations. With a patient's first episode of AF, termination is appropriate, but antiarrhythmic therapy should usually be withheld in order to assess the recurrence pattern. However, if severe hemodynamic or ischemic intolerance would make recurrence a serious risk, or if an early symptomatic recurrence is highly likely, antiarrhythmic therapy would be appropriate. Acute AF may terminate spontaneously or may be terminated iatrogenically. The latter may be achieved by direct current or pharmacologic approaches. The risks, benefits, and optimum utility of these approaches are addressed in the article. Infrequent recurrences may be treated with cardioversion; frequent or severely symptomatic episodes are best treated with attempts at suppression with chronic antiarrhythmic drug administration. Since the therapeutic efficacy of maintaining sinus rhythm is similar for the currently available agents, the drug selection process should be based in large part on safety and convenience considerations. The factors underlying this selection process and one suggested algorithm for drug choice are provided in this article.

Rhythm management in atrial fibrillation--with a primary emphasis on pharmacologic therapy: Part 3

Atrial fibrillation (AF) is the most common, sustained, symptomatic tachyarrhythmia that clinicians are called upon to manage. Management strategies include ventricular rate control coupled with anticoagulation, versus restoration and maintenance of sinus rhythm. Rate control may be achieved pharmacologically, with agents that impair AV nodal conduction directly and/or by increasing parasympathetic/sympathetic balance, or by modifying or ablating the AV nodal region anatomically. Rhythm control may be achieved by electrical or pharmacologic conversion followed by maintenance of sinus rhythm by pharmacologic (or occasionally ablative) therapies. This article will present current approaches to rate and rhythm control issues in atrial fibrillation. Parts 1 and 2, published previously, dealt with rate control and with the restoration of sinus rhythm. Part 3, the current article, details the selection process of choosing a therapy to maintain sinus rhythm, including the likelihood of success, the risks of therapy, and individualization of therapy as dependent upon the nature of the structural heart disease present. It also discusses nonpharmacologic approaches that have been recently developed or are undergoing development. One suggested drug selection algorithm is provided.

Antiarrhythmic drug therapy in the treatment of atrial fibrillation

Treatment of atrial fibrillation is often unsatisfactory because no available drug has been shown to be clearly superior for maintaining patients in sinus rhythm, and all agents have significant potential for toxicity. Selection of an antiarrhythmic drug is more likely to be based on the drug's potential for toxicity, rather than its demonstrated superior efficacy in the treatment of atrial fibrillation. Careful assessment of each patient for contraindications to individual agents and the likelihood of treatment success needs to be done before initiating antiarrhythmic therapy.

Safety of long-term flecainide and propafenone in the management of patients with symptomatic paroxysmal atrial fibrillation: report from the Flecainide and Propafenone Italian Study Investigators

To compare the relative safety of flecainide acetate to propafenone HCl during long-term treatment (12 months), we conducted a randomized, open-label, comparative, parallel, multicenter trial in 200 patients with paroxysmal atrial fibrillation (AF) and no history of heart disease. Initial daily doses were flecainide 200 mg (n = 97) or propafenone 450 mg (n = 103). Dose escalations up to a maximum of flecainide 300 mg/day or propafenone 900 mg/day were permitted after > or = 2 attacks of paroxysmal AF. Patients were assessed for safety and drug tolerance at designated intervals over the 12-month study unless discontinued for adverse experience or inadequate response. Ten patients on flecainide reported 14 cardiac adverse experiences; 4 discontinued the drug. Seven propafenone patients reported 8 cardiac adverse experiences; 5 discontinued the drug. Three proarrhythmic events occurred: 1 propafenone patient developed ventricular tachycardia and 2 flecainide patients experienced AF with a rapid ventricular response. An intention-to-treat analysis showed that the probability of safe and effective treatment after 12 months was 77% for flecainide-treated patients and 75% for the propafenone-treated patients. There was an acceptable risk-benefit profile in patients with paroxysmal AF and no evidence of clinically significant heart disease who were treated with flecainide or propafenone for 12 months. Further, there was no statistically significant difference in safety or efficacy between flecainide and propafenone in this study.

Safety and utility of flecainide acetate in the routine care of patients with supraventricular tachyarrhythmias: results of a multicenter trial. The Flecainide Supraventricular Tachycardia Study Group

Patients with supraventricular arrhythmias have been safely and effectively treated with flecainide. We conducted an open-label, 20-center trial to define further the safety and efficacy profile of oral flecainide in patients with supraventricular arrhythmias, including atrial tachycardias (ectopic or multifocal), atrial-ventricular tachycardias (reentrant), paroxysmal atrial fibrillation/flutter (PAF), and chronic atrial fibrillation (CAF). Our study population of 151 patients with documented supraventricular arrhythmias requiring treatment included 67 with paroxysmal supraventricular tachycardia (PSVT), 67 with PAF (symptoms < 15 days), and 17 with CAF (symptoms > of = 15 days)> The initial flecainide dose of 100 mg twice daily could be increased by 50 mg bid every 4 days to a maximum of 200 mg twice daily. Patients who were effectively treated could receive flecainide for 1 year. The study was terminated April 26, 1989, in response to interim results reported by the Cardiac Arrhythmia Suppression Trial (CAST). All patients were removed from the study by August 1989. At study termination 87% of PSVT, 73% of PAF, and 56% of CAF patients had improved symptomatically while on flecainide therapy. Eleven patients experienced cardiac adverse experiences: proarrhythmic events (3 patients), new or worsened congestive heart failure (7 patients), sinus pauses (1 patient). Cardiac side effects appeared to be more frequent in patients in the CAF group (5/17 patients), all of whom had structural heart disease. Overall, 45 (67%) PSVT, 43 (64%) PAF, and 9 (56%) CAF patients reported at least 1 noncardiac adverse experience; the most common were abnormal vision, dizziness, and headaches. One patient from the CAF group died; the death was considered to be unrelated to flecainide. Flecainide appears to be safe and effective treatment for patients with supraventricular arrhythmias of a variety of mechanisms and appears particularly effective for patients with PSVT. The efficacy is lowest and side effects most frequent in patients with CAF, as seen with other trials of antiarrhythmic medication in these patients. In the context of the CAST experience and other trials of antiarrhythmic drugs in patients with CAF, the balance of risk and benefit of therapy should be considered carefully before initiating treatment.

Prospective comparison of flecainide versus quinidine for the treatment of paroxysmal atrial fibrillation/flutter. The Flecainide Multicenter Atrial Fibrillation Study Group

In order to compare the efficacy and long-term tolerability of flecainide acetate versus quinidine, 239 patients with paroxysmal atrial fibrillation were prospectively treated with flecainide (n = 122) or quinidine (n = 117) in an open-label, randomized trial. All patients were followed for 1 year after initiation of therapy unless their antiarrhythmic drug was discontinued due to an inadequate therapeutic response or intolerable side effects. Although both drugs were equally effective in adequately controlling recurrences of atrial fibrillation (difference, p = 0.282; not significant), fewer flecainide patients had to have their therapy discontinued due to adverse experiences (p = 0.012). Based on both endpoints (efficacy and tolerability), an estimated 70.5% of flecainide versus 55.4% of quinidine patients would remain effectively treated at the end of 1 year on therapy (p < or = 0.007). The findings of this prospective study suggest that in the treatment of paroxysmal atrial fibrillation (1) flecainide and quinidine are equally effective in the acceptable suppression of symptomatic paroxysmal atrial fibrillation; (2) flecainide is better tolerated than quinidine and is less likely to be discontinued due to adverse effects; and (3) given the overall endpoint of efficacy and tolerability, more patients are likely to continue long-term therapy with flecainide than with quinidine.

Efficacy and safety of long-term oral flecainide acetate in patients with responsive supraventricular tachycardia

In 102 patients with inducible supraventricular tachycardia (SVT), 56 women and 46 men aged 20-86 (mean, 52) years, underwent electrophysiologic study. SVTs observed at electrophysiologic study were atrial flutter or atrial fibrillation (32%), the "slow-fast" form of atrioventricular (AV) nodal reentrant tachycardia (45%), orthodromic AV reentrant tachycardia (25%), and atrial tachycardia (9%). More than 1 SVT occurred in some patients. Spontaneous symptomatic SVT frequency prior to oral flecainide varied from 3/day to 1/3 months (mean, 3/month). At electrophysiologic study and during SVT, intravenous flecainide, 2 mg/kg body weight, was given at an infusion rate of 10 mg/min up to a maximum dose of 150 mg. Patients were commenced on oral flecainide if SVT termination occurred during intravenous flecainide administration and if reinitiation was not possible after the total dose of flecainide had been given. In patients with AV nodal reentrant tachycardia and AV reentrant tachycardia further criteria for commencing oral flecainide were SVT termination by ventricular-atrial conduction block and persistent ventricular-atrial block after intravenous flecainide administration. Initial oral flecainide dosage was determined by assessing ability to reinitiate SVT after 50 mg, 100 mg, and the total dose of intravenous flecainide had been given. Eighty-nine patients (87%) remained free of symptomatic SVT over a mean follow-up period of 3.9 years (range, 3 months to 6.5 years). Two thirds were still taking the original dosage of flecainide and the rest were SVT-free on a higher dosage. Oral dosages ranged from 50 to 300 mg/day (median dosage, 100 mg twice daily) Nine patients experienced minor side effects, including, lethargy, dizziness, headache, and blurred vision. There were no deaths and no reports of major proarrhythmic events or other major adverse effects.

Flecainide acetate for paroxysmal supraventricular tachyarrhythmias. The Flecainide Supraventricular Tachycardia Study Group

Flecainide has been shown to be effective in short-term, controlled studies for prevention of paroxysmal supraventricular tachycardia (SVT) and paroxysmal atrial fibrillation (AF). However, it is unknown whether this beneficial response is maintained during long-term chronic therapy. Forty-nine patients were studied who enrolled in double-blind, placebo-controlled, short-term studies of safety and efficacy and subsequently received long-term, open-label therapy for > or = 6 months (mean duration of therapy, 17 months). To evaluate chronic efficacy, events during long-term therapy were documented by a transtelephonic monitor for either 4 or 8 weeks, comparable to the corresponding 4- or 8-week placebo-baseline periods in the same patients. Results during chronic therapy were compared with those at baseline and after the initial (short-term) treatment period. Compared with placebo-baseline results, the number of patients free of arrhythmic attacks increased significantly for both patients with SVT (from 24% to 82%, p = 0.013, n = 17) and patients with AF (from 12% to 68%, p < 0.001, n = 25). Mean time to first attack and mean number of days between attacks also showed significant and parallel increases during the chronic efficacy period. In patients with paired short- and long-term efficacy evaluations with the same dose of flecainide, end points were maintained at equivalent levels or showed further improvement (i.e., mean rate of AF attacks decreased further with chronic therapy, p = 0.036). No proarrhythmic events, death, or myocardial infarction occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

1:1 atrioventricular conduction in atrial flutter with digoxin and flecainide

A 65-year-old man with paroxysmal atrial flutter was treated with digoxin and flecainide. The atrial flutter rate was slowed to 190 beats per minute but at times 1:1 AV conduction occurred.