Sotalol versus quinidine for the maintenance of sinus rhythm after direct current conversion of atrial fibrillation

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.

Atrial fibrillation: prevalence and management in an acute general medical unit

BACKGROUND

Atrial fibrillation (AF) is a common comorbid condition in patients admitted to hospital. In managing patients with AF, recent research has highlighted the importance of heart rate control, cardioversion, maintenance of sinus rhythm and anticoagulation for the prevention of thromboembolism.

AIM

To determine the prevalence of AF in patients admitted acutely to the general medical service at Auckland Hospital and to assess the adequacy of heart rate control, the number cardioverted and the use of warfarin to prevent thromboembolism.

METHODS

Prospective review of all acute admissions to the general medical service over a 12 week period. Information was collected from hospital notes on the patients' present and past medical conditions, admission and discharge cardiac medication and the use of investigations, particularly thyroid function tests and echocardiography. The heart rate on discharge, number cardioverted either during the admission or after discharge and the number given warfarin and aspirin were recorded.

RESULTS

One hundred and forty-seven patients (aged 38-96, mean age 76 years and 52% male) were admitted in AF 165 times out of the 1637 admissions over the study period (a prevalence of 10.4%, 95% CI 8.6-11.5%). The main causes of admission were heart failure (23%), pneumonia or sepsis (17%), cerebrovascular accident (CVA) or transient ischaemic attack (TIA) (14%) and ischaemic heart disease (11%). Past medical history included hypertension (46%), ischaemic heart disease (39%), congestive heart failure (58%), valvular heart disease (12%), chronic obstructive airways disease (24%), CVA, TIA or thromboembolic event (24%) and diabetes (17%). Thyroid function tests were performed in 50% of patients and echocardiograms in 38%. Heart rate control at discharge could not be assessed, as this was not recorded prior to any patient's discharge. Seventy-eight per cent of patients were discharged on digoxin but only 29% on drugs that control the heart rate with exercise. Five patients out of 11 considered for cardioversion had a successful cardioversion in hospital and two were later cardioverted as outpatients. Twenty-eight per cent were discharged on warfarin, 33% on aspirin and one patient on both. Fifty-two per cent were considered to have contraindications to warfarin therapy. Prescribing rates for warfarin did not vary according to the patients' clinical risk for thromboembolism.

CONCLUSION

AF is a common comorbid condition in the acute general medical ward. Standard investigations were under-utilised. Attention needs to be paid to the recording and control of heart rate at rest and on exercise. Cardioversion is considered infrequently. This patient group had a high risk for thromboembolism and after excluding the large group in whom warfarin was contraindicated, warfarin was still under-utilised.

Current antiarrhythmic drugs: an overview of mechanisms of action and potential clinical utility

Reorientation in drug therapy to control cardiac arrhythmias continues to evolve in the wake of ongoing refinements in techniques and indications for radiofrequency ablation and the use of implantable devices for atrial and ventricular arrhythmias. The role of sodium channel blockers continues to be questioned, and data from clinical trials indicate that the use of this class of drugs should be limited to control symptoms in patients who have arrhythmias and either no or minimal heart disease. The decline in the use of sodium channel blockers has led to greater use of beta blockers and complex Class III agents, such as sotalol and amiodarone, as both primary therapy and adjunctive therapy with implantable defibrillators in patients with cardiac disease of varying degrees of ventricular dysfunction. Success with these Class III agents in the context of their side effects has led to the synthesis and characterization of compounds with simpler ion channel-blocking properties. The need for such compounds stemmed from the observation that atrial fibrillation (AF) as an arrhythmia is, for the most part, still not amenable to curative therapy by interventional procedures. The isolated block of the rapid component of the delayed rectifier current (IKr) has been found to have either a neutral (e.g., dofetilide) or deleterious (e.g., d-sotalol) effect on mortality in survivors of myocardial infarction. Thus, the objective of drug development should be the appropriate match between the substrate and an antiarrhythmic drug. The so-called pure Class III agents have been shown to have beneficial antifibrillatory effects in patients with AF. They are effective in inducing acute chemical conversion, preventing paroxysmal AF, and maintaining sinus rhythm in patients with persistent AF restored to sinus rhythm with DC cardioversion. AF is a complex arrhythmia, undoubtedly a result of multifaceted derangement of atrial ionic currents. Attention has therefore focused on newer compounds that have the propensity to block more than one ion channel. Examples of such agents are tedisamil and azimilide, the latter having been studied extensively in humans. It is the first of the Class III agents that block both components (IKr and IKs) of the delayed rectifier current, which results in a spectrum of electrophysiologic properties that includes lack of rate or use dependency in terms of effect on repolarization and refractoriness of atrial and ventricular myocardium. Available but unpublished clinical data indicate that azimilide may be effective over a wide range of tachycardia cycle lengths with a low incidence of torsades de pointes. In these respects, its properties, at least in terms of its use in AF, resemble those of amiodarone. However, the drug has little or no effect on AV conduction, which precludes the modulation of ventricular response in patients relapsing to AF.

Sotalol: Current Status and Expanding Indications

BACKGROUND: The role of antiarrhythmic drug therapy continues to undergo major changes. The change is necessitated by the advent of invasive interventional procedures, such as catheter ablation of arrhythmias and the use of implantable devices for sensing and terminating life-threatening ventricular arrhythmias and symptomatically traublesome supraventricular arrhythmias. Many conventional and time-honored drugs, such as sodium channel blockers, have been found either to be ineffective or to have the potential to produce serious proarrhythmic reactions. Attention is therefore focused on compounds that prolong repolarization and reduce sympathetic stimulation. Two compounds, amiodarone and sotalol, have emerged as prototypes of drugs of the future. METHODS AND RESULTS: This review focuses on sotalol for controlling supraventricular and ventricular tachyarrhythmias. Sotalol is a major antiarrhythmic agent that combines potent class III action with nonselective beta-blocking properties. The drug's pharmacokinetics is simple. Its elimination half-life is 10-15 hours, the drug being excreted almost exclusively by the kidneys. Sotalol's pharmacokinetics allows development of optimal dosing for initiation of therapy relative to changes in creatinine clearance with further dose adjustment by monitoring the QT interval on the surface electrocardiogram. The compound exerts broad-spectrum antiarrhythmic actions in supraventricular and ventricular arrhythmias. It prevents inducible ventricular tachycardia (VT) and ventricular fibrillation (VF) in approximately 30% of patients with a higher figure for the suppression of spontaneously occurring arrhythmias documented on Holter recordings. CONCLUSIONS: The major role of sotalol is in the management of VT/VF often in conjunction with an implantable cardioverter/defibrillator, in which context it lowere the defibrillation threshold. Sotalol is superior to class I agents, especially in VT/VF and in survivors of cardiac arrest. Sotalol has emerged as a major antifibrillatory compound for the control of life-threatening ventricular arrhythmias as the main indication. Data have indicated its potential for the maintenance of stability of sinus rhythm in patients with atrial fibrillation and flutter after electrical conversion and in preventing their occurrence in a variety of clinical settings.

Initial experience with a new balloon-guided single lead catheter for internal cardioversion of atrial fibrillation and dual chamber pacing

BACKGROUND

Based on the observation that internal cardioversion (IntCV) of atrial fibrillation is effective with electrodes in the right atrium and pulmonary artery, a new balloon-guided catheter and external defibrillation device with optional dual chamber pacing was evaluated.

METHODS

IntCV was attempted in 27 patients (age: 57 +/- 10 years, duration: 14 +/- 18 months, left atrial diameter 56 +/- 8 mm) using a new defibrillation device (Alert, EP MedSystems, Inc., NJ, USA) that allows the delivery of biphasic shocks (0.5-15 J, variable tilt), atrial and ventricular pacing, and online signal recording. Pacing and defibrillation shocks were applied via a 7.5 Fr balloon-guided catheter (EP MedSystems, Inc.). Pacing, sensing, and triggering were established through the proximal atrial array and an electrode ring between both defibrillation arrays and a single ventricular electrode ring. Catheters were inserted from the antecubital vein.

RESULTS

In 25 of 27 patients sinus rhythm was restored with a mean energy of 6.7 +/- 4.5 J. In five patients, atrial postshock pacing was required for bradycardia and atrial premature beats. The mean fluoroscopy time was 2.0 +/- 1.3 minutes.

CONCLUSION

The high success rate, ease of application, and backup dual chamber pacing suggest that this system is an alternative to established methods of cardioversion. In certain indications, such as failure of prior external cardioversion and situations in which a standard pulmonary balloon catheter is needed, this system would be advantageous.

Long-term outcome of patients with drug-refractory atrial flutter and fibrillation after single- and dual-site right atrial pacing for arrhythmia prevention

OBJECTIVES

An initial crossover study comparing dual- and single-site right atrial pacing was performed followed by a long-term efficacy and safety evaluation of dual-site right atrial pacing in patients with drug-refractory atrial fibrillation (AF). Also examined was the efficacy of two single-site right atrial pacing modes (high right atrium and coronary sinus ostium) and the long-term need for cardioversion, antithrombotic and antiarrhythmic drug therapies during dual-site atrial pacing.

METHODS

Thirty consecutive patients with drug-refractory symptomatic AF and documented primary or drug-induced bradycardia were implanted with a dual chamber rate-responsive pacemaker and two atrial leads. Single-site atrial pacing was performed at the high right atrium or the coronary sinus ostium. Continuous atrial pacing was maintained.

RESULTS

Mean arrhythmia-free intervals increased from 9+/-10 days in the control period preceding implant to 143+/-110 days (p < 0.0001) in single-site right atrial pacing and 195+/-96 days in dual-site right atrial pacing (p < 0.005 versus single-site pacing and p < 0.0001 versus control). Dual-site right atrial pacing significantly increased the proportion of patients free of AF recurrence (89%) as compared to single-site right atrial pacing (62%, p = 0.02). High right atrial pacing and coronary sinus ostial pacing had similar efficacy for AF prevention. Effective rhythm control was achieved in 86% of patients during dual right atrial pacing. Seventy-eight percent of patients at 1 year and 56% at 3 years remained free of symptomatic AF. The need for cardioversion was reduced after pacemaker implant (p < 0.05) and antithrombotic therapy was reduced (p < 0.06) without any thromboembolic event. Coronary sinus ostial lead dislodgement was not observed after discharge.

CONCLUSIONS

Atrial pacing in combination with antiarrhythmic drugs eliminates or markedly reduces recurrent AF. Prevention of AF is enhanced by dual-site right atrial pacing. High right atrial and coronary sinus ostial pacing do not differ in efficacy. Dual-site right atrial pacing is safe, achieves long-term rhythm control in most patients, decreases the need for cardioversion, and antithrombotic therapy can be selectively reduced.

Propafenone for the treatment of supraventricular tachycardia and atrial fibrillation: a meta-analysis

The purpose of this study was to determine propafenone's effectiveness in terminating and suppressing supraventricular arrhythmias using meta-analytic techniques. Published abstracts and manuscripts with these goals were selected and data abstracted on conversion and maintenance of sinus rhythm. Data were pooled using standard meta-analytic techniques and analyzed according to observation times, trial design (randomized versus nonrandomized), and route of drug administration. Propafenone successfully terminated 83.8% (95% confidence interval 78.1-89.7%) of supraventricular tachycardias. For supraventricular tachycardias, the proportion of patients remaining in sinus rhythm without recurrent arrhythmia was 64.6% (58.1-71.1%) at 1 year. The likelihood of converting a paroxysm of atrial fibrillation (AF) increased over time, with 76.1% (72.8-79.4%) of patients in sinus rhythm 24 hours after initiation of therapy. Patients receiving intravenous therapy were more likely to convert to sinus rhythm in the first 4 hours after drug administration. The treatment benefit of propafenone versus placebo in converting sinus rhythm was greatest in the first 8 hours after treatment (treatment benefit of 31.5% [24.5-38.5%] at 4 hours and 32.9% [24.3-41.5%] at 8 hours, p <0.01). This treatment benefit decreased to 1 1.0% (-0.6-22.4%) after 24 hours. Propafenone was effective in suppressing recurrences of AF in 55.4% (51.3-59.7%) at 6 months and 56.8% (52.3-61.3%) at 12 months. Thus, propafenone is effective in terminating supraventricular tachycardias and AF in the vast majority of patients. Suppression of arrhythmia recurrences is feasible in most patients, although its effectiveness decreases over time.

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.

The peri-operative management of atrial fibrillation

Atrial fibrillation is a common arrhythmia frequently seen in surgical patients. The onset of new atrial fibrillation during the peri-operative period is less common. There are many possible precipitating factors, although volatile agents themselves may have an antifibrillatory action. The management of atrial fibrillation includes removal of any precipitating factors and treatment of the arrhythmia itself. Immediate management of acute-onset atrial fibrillation is usually direct current cardioversion. Alternatively, anti-arrhythmic drugs can be used to achieve cardioversion. In patients with rapid, chronic atrial fibrillation or those refractory to cardioversion, priority is given to control of the ventricular rate. Thrombo-embolism is a significant risk if atrial fibrillation is paroxysmal or persists for more than 48 h.

Significance of Supraventricular Tachyarrhythmias After Coronary Artery Bypass Graft Surgery and Their Prevention by Low-Dose Sotalol: A Prospective Double-Blind Randomized Placebo-Controlled Study

BACKGROUND: The single most frequent complication after coronary artery bypass graft surgery is the occurrence of supraventricular tachyarrhythmias leading to a prolonged hospital stay. Although several drugs have been used to treat these arrhythmias, effective prevention was only possible with beta-blocking drugs in selected patients. It was, therefore, the aim of the present study to evaluate the significance of supraventricular tachyarrhythmias in presence of today's cardioprotective management in a broad spectrum of patients and to assess the possible preventive effect and safety of low-dose sotalol after coronary artery bypass graft surgery. METHODS AND RESULTS: In a prospective randomized double-blind placebo-controlled trial, 220 consecutive patients referred for elective coronary artery bypass graft surgery were randomized to 80 mg sotalol twice daily (n = 110) or matching placebo (n = 110) for 3 months with the first dose given 2 hours before surgery. There were no significant differences in baseline characteristics between the two groups. Low-dose sotalol reduced the rate of supraventricular arrhythmias from 43% (placebo) to 25% (sotalol, P <.01), which was atrial fibrillation in 83%, flutter in 7%, and other supraventricular arrhythmias in 10%. Only 7% of all arrhythmias were observed after day 9. Hospital stay was 11 +/- 4 days in patients with supraventricular arrhythmias versus 9 +/- 2 days (P <.001) in patients without. On the fourth postoperative day, heart rate was lower in the sotalol group (75 +/- 12 versus 86 +/- 14 beats per min; P <.0001), but QTc was not significantly prolonged (sotalol, 0.44 +/- 0.03; placebo, 0.43 +/- 0.03; P, ns). Study medication had to be discontinued due to side effects in 6.4% of sotalol and 3.6% of placebo patients (P, ns), but relevant side effects occurred only in two sotalol patients late after surgery. CONCLUSIONS: These data show that without antiarrhythmic therapy the incidence of supraventricular arrhythmias after coronary artery bypass graft surgery is high (43%) and that supraventricular arrhythmias were associated with a prolonged hospital stay (+/-2 days). Prophylactic treatment with low-dose sotalol reduced the incidence of supraventricular arrhythmias significantly (by 40%), thereby reducing overall hospital stay in treated patients. Because more than 90% of all supraventricular arrhythmic episodes occurred within 10 days after surgery and considering the small proarrhythmic effect of sotalol late after surgery, prophylactic treatment with sotalol may be recommended for the first 10 postoperative days to safely reduce supraventricular tachyarrhythmias.

Prospective comparison of flecainide versus sotalol for immediate cardioversion of atrial fibrillation

This study sought to compare the efficacy and safety of intravenous flecainide and sotalol for immediate cardioversion of atrial fibrillation. We performed a prospective, randomized, single-blind, multicenter trial, including 106 hemodynamically stable patients with atrial fibrillation, stratified according to duration of the arrhythmia. Exclusion criteria included severely reduced left ventricular systolic function, recent antiarrhythmic therapy, and hypokalemia. Patients were randomly assigned to receive either intravenous flecainide or intravenous sotalol. Trial medication was given at a dose of 1.5 mg/kg body weight (maximum 150 mg). Overall, 28 of 54 patients (52%) given flecainide and 12 of 52 patients (23%) given sotalol converted to sinus rhythm during the first 2 hours after start of the infusion (p = 0.003). Multivariate analysis confirmed that treatment allocation to flecainide, an arrhythmia duration of < or = 24 hours, higher plasma magnesium level at baseline, higher age for men, and lower age for women independently increases the probability of conversion. The frequency of adverse effects was not significantly different in the 2 treatment groups.

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.

Low-dose amiodarone versus sotalol for suppression of recurrent symptomatic atrial fibrillation

To compare the safety and efficacy of amiodarone and sotalol in the treatment of patients with recurrent symptomatic atrial fibrillation (AF), 70 patients were entered into a randomized, double-blind study. Of these, 35 received amiodarone and 35 sotalol. There were no significant differences in baseline clinical characteristics between groups. Patients with ejection fraction < 40% or clinically significant heart disease were excluded. Patients randomized to amiodarone began with 800 to 1,600 mg/day for 7 to 14 days orally. After the initial loading phase, the drug dose was tapered to maintenance levels over 7 to 12 days; thereafter, therapy was generally maintained at a dosage of 200 mg/day. The sotalol dosage was 80 to 360 mg twice daily, as tolerated. Follow-up clinical evaluations were conducted at 1, 2, 4, 6, 9, and 12 months. The proportion of patients remaining in sinus rhythm on each agent was calculated for the 2 groups using the Kaplan-Meier method. Ten of the 35 patients who were taking amiodarone developed AF during the 12-month observation period, compared with 21 of the 35 who were taking sotalol (p = 0.008). No significant effect of sex, age, left atrial size, or type of AF could be detected that increased the risk of development of AF. We conclude that both amiodarone and sotalol can be used for the maintenance of normal sinus rhythm in patients with recurrent symptomatic AF but that amiodarone is the more effective of the 2 drugs for this purpose.

Impact of structural heart disease on the selection of class III antiarrhythmics for the prevention of atrial fibrillation and flutter

Antiarrhythmic agents may be beneficial or harmful. Among the harmful effects, or risks, is proarrhythmia. One of several factors that underlie proarrhythmic risk is the presence and nature of any underlying structural heart disease at the time of antiarrhythmic drug administration. The structural disease-antiarrhythmic drug interaction has been best studied and clearly delineated for class I antiarrhythmics. This review provides information to suggest that structural disease can enhance proarrhythmic risk with class III drugs as well, although this is least evident with amiodarone. Particularly pertinent are disorders that prolong action potential duration (such as ventricular hypertrophy or chronic dilatation), inhomogeneous dispersion of refractoriness (including conditions with cellular uncoupling), and reduced ventricular fibrillation threshold. These issues must be considered when choosing an antiarrhythmic drug for atrial and for ventricular arrhythmias and when selecting the dosing and monitoring protocol to be used.

Update on Atrial Fibrillation: Restoration of Sinus Rhythm or Ventricular Rate Control?

In patients with persistent atrial fibrillation, two therapeutic alternatives exist, namely restoration and maintenance of sinus rhythm versus ventricular rate control combined with anticoagulation. Currently, the selection of the best therapeutic strategy in an individual patient relies for the most part on clinical judgement and personal experience. At present, there are no prospective scientific data to support the superiority of one treatment over the other with respect to overall survival or quality of life. This review summarizes the present knowledge on this important clinical problem with particular emphasis on issues such as efficacy of antiarrhythmic drugs to prevent recurrent atrial fibrillation, proarrhythmic hazards of these compounds, or efficacy and safety of anticoagulation in nonrheumatic atrial fibrillation. These data serve as the basis of ongoing clinical trials prospectively comparing the merits and demerits of the two therapeutic strategies in the most common arrhythmia encountered in clinical practice.

Effects of antiarrhythmic drugs on variability of ventricular rate and exercise performance in chronic atrial fibrillation complicated with ventricular arrhythmias

For conversion of atrial fibrillation to sinus rhythm and management of ventricular arrhythmias, antiarrhythmic drugs were frequently used. However, the effects of antiarrhythmic drugs on exercise performance and on the variability of ventricular rate were not available. This study included 37 patients who had chronic atrial fibrillation complicated with symptomatic ventricular arrhythmias. The patients were divided into three groups and received sotalol, propafenone, and procainamide, respectively. Before and after taking the drugs for 14 days, these patients received treadmill exercise test, 24 h Holter electrocardiogram, and tilt table test for evaluation of the exercise performance and the variability of ventricular rate (including the mean RR intervals, mRR, the standard deviation of RR intervals, SDRR, and the root mean square of the difference in successive RR intervals, rMSSD). All these antiarrhythmic drugs could suppress ventricular arrhythmia but only sotalol could significantly increase the exercise duration (374+/-50 to 476+/-55 s, P=0.02), and reduce the maximal heart rate (186+/-23 to 136+/-16 beats/min, P=0.01) during exercise test. Furthermore, only sotalol increased the mRR (777+/-60 to 885+/-66 ms, P=0.02), SDRR (190+/-40 to 216+/-48 ms, P=0.04) and rMSSD (223+/-48 to 253+/-40 ms, P=0.03) during 24 h Holter electrocardiogram. With head-up tilt, the mRR, SDRR and rMSSD all decreased significantly before drug therapy, and these changes were still present only after propafenone therapy. Therefore, comparisons among sotalol, propafenone and procainamide showed that sotalol increased the exercise performance and the variability of ventricular rate in patients who had chronic atrial fibrillation complicated with symptomatic ventricular arrhythmias.

Acute treatment of atrial fibrillation

Atrial fibrillation (AFib) is a common clinical entity, responsible for significant morbidity and mortality, but it also accounts for a large percentage of healthcare dollar expenditures. Efforts to treat this arrhythmia in the past have focused on subacute antithrombotic therapy and eventually use of antiarrhythmic drugs for maintenance of sinus rhythm. However, there has been a growing interest in the concept of acute electrical and pharmacologic conversion. This treatment strategy has a number of benefits, including immediate alleviation of patient symptoms, avoidance of antithrombotic therapy, and prevention of electrophysiologic remodeling, which is thought to contribute to the perpetuation of the arrhythmia. There is also increasing evidence that this is a cost-effective strategy in that it may obviate admission to the hospital and the cost of long-term therapy. This article represents a summary of the treatments that may be used acutely to control the ventricular response to AFib, prevent thromboembolic events, and provide for acute conversion either pharmacologically or electrically. It includes information on modalities that are currently available and those that are under active development. We anticipate that an active, acute treatment approach to AFib and atrial flutter will become the therapeutic norm in the next few years, especially as the benefits of these interventions are demonstrated in clinical trials.

Likelihood of spontaneous conversion of atrial fibrillation to sinus rhythm

OBJECTIVES

We sought to determine the likelihood and predictors of spontaneous conversion to sinus rhythm of recent-onset atrial fibrillation (symptoms <72 h).

BACKGROUND

Although spontaneous conversion of recent-onset atrial fibrillation is common, the likelihood and clinical and echocardiographic predictors have not been fully defined. Such data would be important for management of patients in whom early cardioversion is desired: Cardioversion could be delayed in patients with a high likelihood of spontaneous conversion, and it could be expeditiously pursued if spontaneous conversion is unlikely.

METHODS

We screened 1,822 consecutive adults admitted to the hospital with atrial fibrillation and prospectively identified 356 patients (45% male, mean age +/- SD 68 +/- 16 years) with atrial fibrillation of <72-h duration. The occurrence of spontaneous conversion to sinus rhythm and clinical and echocardiographic data were identified through retrospective chart review.

RESULTS

Spontaneous conversion to sinus rhythm occurred in 68% of the study group (n = 242; 95% confidence interval [CI] 63% to 73%). Among patients with spontaneous conversion, the total duration of atrial fibrillation was <24 h in 159 (66%), 24 to 48 h in 42 (17%) and >48 h in 41 (17%) (p < 0.001). Logistic regression analysis of clinical data identified presentation <24 h from onset of symptoms as the only predictor of spontaneous conversion (odds ratio 1.8, 95% CI 1.4 to 2.4, p < 0.0001). Normal left ventricular systolic function was more common among patients with spontaneous conversion (p = 0.03), but it was not an independent predictor of conversion. Left atrial dimension was similar between groups.

CONCLUSIONS

Spontaneous conversion to sinus rhythm occurs in almost 70% of patients presenting with atrial fibrillation of <72-h duration. Presentation with symptoms of <24-h duration is the best predictor of spontaneous conversion.

Treatment strategies for atrial fibrillation

Atrial fibrillation is the most common arrhythmia observed in clinical practice, occurring in 0.4% of the general population and in up to 4% of people greater than 60 years old. It is often associated with other cardiovascular disorders, such as hypertension, coronary artery disease, or cardiomyopathy. Critical evaluation and management of patients with atrial fibrillation requires knowledge of etiology, prognosis, and treatment options of this arrhythmia. On initial presentation, emergency electrical cardioversion should be performed if the patient is hemodynamically unstable. If the patient is stable, initial rate control is recommended, using atrioventricular nodal blocking agents. Further treatment mainly depends upon the duration of the episode. Patients who are in atrial fibrillation <48 hours can be safely cardioverted. Patients who are in atrial fibrillation for >48 hours are commonly anticoagulated for 3 to 4 weeks before and after cardioversion because of the risk of thromboembolism formation in the left atrial appendage. An alternate strategy, which is especially attractive when immediate cardioversion is desired, is transesophageal echocardiography to exclude left atrial thrombus followed by prompt cardioversion. After cardioversion, sinus rhythm can be maintained with class I and III drugs, such as flecainide and propafenone or amiodarone and sotalol. New treatment options, such as atrial defibrillation, atrioventricular junctional ablation, or modification of atrial pacing to prevent atrial fibrillation, are currently under investigation. Although atrial fibrillation is so common in clinical practice, it still remains difficult to treat. Conversion and maintenance to sinus rhythm with antiarrhythmic drug therapy has not shown any improvement in mortality, and some patients may benefit more from ventricular rate control. This review article discusses different treatment strategies for patients with atrial fibrillation.

Efficacy of a new balloon catheter for internal cardioversion of chronic atrial fibrillation without anaesthesia

OBJECTIVE

To compare a new internal cardioversion system incorporated into a balloon guided catheter with a conventional two electrode system in patients with atrial fibrillation (AF).

DESIGN

Prospective study.

PATIENTS

74 patients with chronic AF treated by internal cardioversion.

MATERIALS

A 7.5 F balloon catheter with high energy electrode arrays each consisting of six 0.5 cm platinum rings. Brachial vein access enables one electrode array to be placed in the left pulmonary artery (distal pole) and the other at the lateral right atrial wall (proximal pole). The conventional two electrode system consists of 6 F electrodes placed in the proximal left pulmonary artery (anode) and the lower right atrium.

INTERVENTIONS

Internal cardioversion was performed by shocks delivered in 40 V incremental steps from an external defibrillator. Shocks were applied by the new device to 32 patients (group A) and by the conventional system to 42 patients (group B).

RESULTS

The groups differed with respect to system positioning (9.2 (7.3) upsilon 12.3 (8.1) minutes, p < 0.05) and fluoroscopy times (1.7 (1.0) v 3.3 (2.1) minutes, p < 0.01). Sinus rhythm was restored in 30 patients of group A and in 39 of group B (NS) with mean (SD) energy requirements of 8.4 (3.1) J and 7.2 (3.1) J, respectively (NS).

CONCLUSIONS

This new method of internal cardioversion has comparably high primary success rates and low sedation requirements with single and two lead systems.

Factors influencing long term persistence of sinus rhythm after a first electrical cardioversion for atrial fibrillation

It is conventionally thought that electrical cardioversion in patients with atrial fibrillation (AF) of longstanding duration or with a large left atrial diameter, only seldom results in long term success. Recurrence is common, although antiarrhythmic drugs often effectively decrease the number and duration of recurrent AF episodes. We analysed clinical, functional and pharmacological variables which could possibly influence the long term outcome after a first electrical cardioversion for AF in a retrospective study on 85 patients. Univariate and multivariate analysis was used to identify factors predicting maintenance of sinus rhythm at 100 days, and absence of recurrence during the entire follow-up. In univariate analysis, the only significant predictor for maintenance of sinus rhythm at 100 days was the duration of the preceding AF episode. Multivariate analysis with persistence of sinus rhythm at 100 days as endpoint confirmed this as a prognostic factor (p < 0.03), but sotalol treatment also contributed to maintenance of sinus rhythm (p < 0.05). When considering the entire observation period, class III antiarrhythmic drugs, i.e. sotalol and amiodarone, were useful in preventing recurrence (p < 0.01 and < 0.02). High age (above 75 years) was a predictor of recurrence. In conclusion, class III antiarrhythmic drugs, the duration of atrial fibrillation and high age were the most important determinants of long term outcome, while echocardiographic parameters and the presence of heart disease played no role.

Early recurrences of atrial fibrillation after electrical cardioversion: a result of fibrillation-induced electrical remodeling of the atria?

OBJECTIVES

We sought to investigate whether, in humans, the timing and incidence of a relapse of atrial fibrillation (AF) during the first month after cardioversion indicates the presence of electrical remodeling and whether this could be influenced by prevention of intracellular calcium overload during AF.

BACKGROUND

Animal experiments have shown that AF induces shortening of the atrial refractory period, resulting in an increased vulnerability for reinduction of AF. This electrical remodeling was completely reversible within 1 week after cardioversion of AF and was presumably related to intracellular calcium overload.

METHODS

Using transtelephonic monitoring in 61 patients cardioverted for chronic AF, we evaluated the daily incidence of recurrence of AF and determined, by Cox regression analysis, the influence of patient characteristics and medication on relapse of AF.

RESULTS

During 1 month of follow-up, 35 patients (57%) had a relapse of AF, with a peak incidence during the first 5 days after cardioversion. Furthermore, in patients with a recurrence of AF, there was a positive correlation between the duration of the shortest coupling interval of the premature atrial beats after cardioversion and the timing of the recurrence of AF (p = 0.0013). Multivariate analysis revealed that the use of intracellular calcium-lowering drugs during AF was the only significant variable related to maintenance of sinus rhythm after cardioversion (p = 0.03).

CONCLUSIONS

The daily distribution of recurrences of AF suggests a temporary vulnerable electrophysiologic state of the atria. Use of intracellular calcium-lowering medications during AF appeared to reduce recurrences, possibly due to a reduction of electrical remodeling during AF.

Cost effectiveness of inpatient initiation of antiarrhythmic therapy for supraventricular tachycardias

This study assessed the cost effectiveness of inpatient antiarrhythmic therapy initiation for supraventricular tachycardias using a metaanalysis of proarrhythmic risk and a decision analysis that compared inpatient to outpatient therapy initiation. A MEDLINE search of trials of antiarrhythmic therapy for supraventricular tachycardias was performed, and episodes of cardiac arrest, sudden or unexplained death, syncope, and sustained or unstable ventricular arrhythmias were recorded. A weighted average event rate, by sample size, was calculated and applied to a clinical decision model of therapy initiation in which patients were either hospitalized for 72 hours or treated as outpatients. Fifty-seven drug trials involving 2,822 patients met study criteria. Based on a 72-hour weighted average event rate of 0.63% (95% confidence interval, 0.2% to 1.2%), inpatient therapy initiation cost $19,231 per year of life saved for a 60-year-old patient with a normal life expectancy. Hospitalization remained cost effective when event rates and life expectancies were varied to model hypothetical clinical scenarios. For example, cost-effectiveness ratios for a 40-year-old without structural heart disease and a 60-year-old with structural heart disease were $37,510 and $33,310, respectively, per year of life saved. Thus, a 72-hour hospitalization for antiarrhythmic therapy initiation is cost effective for most patients with supraventricular tachycardias.

The medical management of atrial fibrillation

Atrial fibrillation is an extremely common arrhythmia that is associated with significant sequelae. Certain aspects of therapy, such as anticoagulation, are studied in well-constructed randomized trials. Other therapy, such as the maintenance of sinus rhythm with antiarrhythmic agents, is supported by limited evidence. This article reviews the epidemiology and medical treatment of this arrhythmia, addressing anticoagulation, ventricular rate control, and restoration and maintenance of sinus rhythm. Randomized trials in progress that attempt to answer important questions in the management of atrial fibrillation are also discussed.

Atrial fibrillation: antiarrhythmic therapy versus rate control with antithrombotic therapy

Atrial fibrillation is a major health problem in the United States, but the best strategies for treating it have not been rigorously determined in clinical studies. Specifically, there is a paucity of data comparing the approach of maintaining sinus rhythm using prophylactic antiarrhythmic drug therapy with the approach of controlling the ventricular response to atrial fibrillation while reducing embolic events with concomitant antithrombotic therapy. Until ongoing randomized trials are completed, which patients benefit most from a specific approach cannot be determined with certainty. In general, the most reasonable strategies include (1) the restoration of sinus rhythm (without prophylactic antiarrhythmic therapy) after the patient's first episode of atrial fibrillation; and (2) the maintenance of sinus rhythm (including the use of prophylactic antiarrhythmic therapy) in patients who remain symptomatic despite adequate rate control, and who are not at high risk for proarrhythmia and/or are unlikely to maintain sinus rhythm. The risks and benefits need to be carefully weighed in patients with truly asymptomatic atrial fibrillation. Many patients may require multiple attempts to maintain sinus rhythm. Current investigative treatment modalities (e.g., ablation techniques, atrial implantable cardioverter-defibrillators, new antiarrhythmic agents) are likely to alter the current approaches to atrial fibrillation.

The side effect profile of class III antiarrhythmic drugs: focus on d,l-sotalol

Class III antiarrhythmic drugs have been under extensive clinical investigation as safer, more effective alternatives to class I drugs, which have recognized risks in selected populations. Class III drugs prolong the action potential duration of myocardial cells, resulting in a lengthening of the effective refractory period. This pharmacologic activity has antiarrhythmic properties, but it may induce a distinctive form of proarrhythmia known as torsades de pointes. Amiodarone and d,l-sotolol are class III drugs that have been available for many years. In addition to their ability to prolong refractoriness, these drugs have other pharmacodynamic properties. Recent antiarrhythmic drug discovery has focused on the identification and development of selective or so-called pure class III drugs that are devoid of additional actions. Investigators have hoped that these drugs would be as effective as sotalol and amiodarone but have fewer adverse effects. Accumulating data, however, indicate that complex compounds exhibiting antiadrenergic and other electrophysiologic properties may be superior to pure class III agents.

Controlling cardiac arrhythmias: an overview with a historical perspective

During the past decade, several developments in our knowledge of antiarrhythmic drugs have had a major influence on our approach to their use. These developments may be summarized as follows: (1) it has become clear that arrhythmias merit treatment only for the relief of symptoms, with improved quality of life, and for prolongation of survival by reducing arrhythmic deaths; (2) suppression of arrhythmias--symptomatic or asymptomatic--may not necessarily decrease mortality, the net impact on mortality being agent-specific; (3) antiarrhythmic drugs have the propensity to decrease as well as to increase cardiac arrhythmias (producing proarrhythmias); (4) the most important determinant of arrhythmia mortality is the degree and nature of ventricular dysfunction; and (5) only controlled trials have the potential to establish the effect of treatment on mortality in patients with cardiac arrhythmias. To these considerations must be added the advances in nonpharmacologic approaches to controlling cardiac arrhythmias. These include catheter ablation of cardiac arrhythmias, certain surgical techniques that in selected patients offer prospects of cure, and the development of implantable ventricular and atrial cardioverter defibrillators, which allow the evaluation of drugs versus placebo against the background of the defibrillator. This is particularly germane in the case of life-threatening symptomatic ventricular arrhythmias such as sustained ventricular tachycardia and ventricular fibrillation. Antiarrhythmic drugs and implantable devices in the control of arrhythmias cannot be considered in isolation. Their role in mortality reduction needs to be defined alone as well as in combination by controlled clinical trials.

Cardioversion of atrial fibrillation and subsequent maintenance of sinus rhythm

This article gives an overview of electrical cardioversion of AF and includes the discussion of newer strategies. DC external cardioversion is highly effective and carries a low risk of complications. Other approaches, like transesophageal cardioversion and high energy internal cardioversion, may improve the acute success rate but do not enhance long-term maintenance of sinus rhythm compared to external cardioversion. An atrial defibrillator may have important advantages which relate to the fact that the duration and possibly also the number of AF episodes become reduced. Supposedly, shortening the attacks of AF may exert an antiarrhythmic effect by limiting electrical, anatomical, and neurohumoral remodeling. So far, low energy biatrial defibrillation using an atrial defibrillator seems to be effective and safe (i.e., does not induce ventricular arrhythmias). However, discomfort limits its tolerability in clinical practice. Future improvement of leads and light sedation that is easy to administer may overcome this problem. In the second part of this overview, the probability of AF recurrence using a serial cardioversion approach is discussed. In middle-aged patients with a fair exercise tolerance and an arrhythmia duration < than 36 months this approach may be worthwhile. Young patients (age < 57 years) with an arrhythmia duration < 3 months and without hypertension may be cured from the arrhythmia with a single shock and without the institution of antiarrhythmic drugs. However, the serial electrical cardioversion approach is unlikely to succeed in elderly patients with a duration of AF exceeding 36 months and a poor exercise tolerance (NYHA Functional Class III or IV).

Antiarrhythmic drug therapy in the management of atrial fibrillation

Antiarrhythmic drugs have been used for the acute conversion of atrial fibrillation to sinus rhythm, as well as for the long-term maintenance of sinus rhythm. In recent years, concerns regarding antiarrhythmic drug efficacy as well as safety have prompted a re-examination of the indications for antiarrhythmic therapy in patients with atrial fibrillation. This review will focus on the safety and efficacy of antiarrhythmic therapy in the acute and chronic management of patients with atrial fibrillation.

A comparison of transvenous atrial defibrillation of acute and chronic atrial fibrillation and the effect of intravenous sotalol on human atrial defibrillation threshold

The comparative efficacy and safety of transvenous defibrillation for acute and chronic AF and the effect of antiarrhythmic agents on this therapy have not been evaluated. Transvenous atrial defibrillation was performed in 25 patients with chronic AF and 13 patients with acute AF by delivering R wave synchronized, biphasic shocks between the right atrium and coronary sinus. The lowest energy and voltage resulting in successful defibrillation were considered to be atrial defibrillation threshold (ADFT). Intravenous sotalol (1.5 mg/kg) was then given over 15 minutes and ADFT was determined again. The mean ADFT was 1.5 J and 3.6 J for acute and chronic AF, respectively, and the threshold was highly reproducible. Sotalol reduced ADFT in patients with acute AF while the reduction in chronic AF group was not significant. There was no significant increase in creatinine kinase nor reduction in blood pressure, but prolonged pause after successful defibrillation required ventricular supporting pacing. We conclude that transvenous atrial defibrillation is a safe and effective means for defibrillating both acute and chronic AF. ADFT was lower in acute AF than in chronic AF. ADFT was highly reproducible during repeated defibrillation. Sotalol reduced ADFT in acute AF and to a lesser extent in chronic AF, and increased the defibrillation success rate. Ventricular pacing will often be required because of prolonged pause after successful defibrillation.

Sotalol Is More Powerful Than Propranolol in Suppressing Complex Ventricular Arrhythmias

BACKGROUND: Sotalol has combined type II and type III antiarrhythmic properties. Although the beta-blocking action of sotalol is thought to contribute to its antiarrhythmic actions, few data are available from direct comparative clinical trials with pure beta-blocking drugs. METHODS AND RESULTS: In this double-blind, randomized, multicenter, placebo-controlled, parallel study, we have compared the antiarrhythmic efficacy and safety of treatment with sotalol vs propranolol in 181 patients with organic heart disease and frequent (>30 ventricular premature complexes [VPCs]/h) repetitive ventricular premature complexes. Eighty-seven were randomized to receive sotalol and 94 received propranolol. The demographic and clinical characteristics of the two groups were identical, and the majority of patients had coronary artery disease or hypertensive heart disease. Most patients had a long-standing history (>5 years) of ventricular arrhythmias and, in a significant proportion, antiarrhythmic therapy with other drugs had failed in the past. After withdrawal of all antiarrhythmic drugs and 1 week of placebo, qualified patients were randomized to sotalol (320 mg/day) or propranolol (120 mg/day). patients not achieving adequate response were given higher doses of sotalol (640 mg/day) or propranolol (240 mg/day)At baseline, both groups had comparable frequency of total VPCs/hour (274/h and 255/h for sotalol and propranolol groups, respectively) which was reduced to 71 VPCs/h and 109/VPCs/h, respectively, at the end of phase 1. At final evaluation there was a significantly greater response to sotalol as demonstrated by 80% reduction in VPCs/hour with sotalol compared with only 50% reduction noted in the propranolol group. Adequate therapeutic response was also achieved in a significantly greater percentage of patients on sotalol compared with propranolol (56% vs 29%, P =.02). Sotalol was also superior to propranolol in suppressing the VT events/day during phase 1 (89% vs 78% reduction in VT events/day, P <.05). Sotalol was more effective than propranolol in all subgroups and in patients with heart rate <75 beats per minute. CONCLUSIONS: Sotalol is more powerful than propranolol in suppressing ventricular arrhythmias documented on Holter recordings. The superiority of sotalol appears to be related to its combined class II and class III antiarrhythmic actions.

Patient characteristics and underlying heart disease as predictors of recurrent atrial fibrillation after internal and external cardioversion in patients treated with oral sotalol

The aim of this study was to identify predictors for recurrent atrial fibrillation after internal and external cardioversion in 157 patients. After cardioversion, patients were treated orally with sotalol (174 +/- 54 mg/day). Univariate predictors for recurrence included coronary artery disease (p < 0.05) and advanced age (p < 0.05). Multivariate adjusted risk for relapse increased with the presence of coronary artery disease (odds ratio [OR] 3.4, 95% confidence interval [CI] 1.6 to 8.0), presence of atrial fibrillation > 2 months before cardioversion (OR 2.3; 95% CI 1.4 to 4.5), left atrial diameter > 60 mm (OR 2.1; 95% CI 1.2 to 3.1), and age > 65 years (OR 1.6; 95% CI 1.3 to 3.3). In 26% of patients with lone atrial fibrillation, recurrence was observed compared with 51% of patients with underlying structural heart disease (p < 0.05). The mode of conversion, internal or external, had no impact on the recurrence rate. These findings might be useful for selection of the most appropriate therapy for the individual patient.

Efficacy and safety of sotalol in patients with refractory atrial fibrillation or flutter

Sotalol's usefulness in treatment of atrial fibrillation and atrial flutter is unproven. This study evaluated (1) the efficacy of sotalol in preventing recurrences of paroxysmal atrial fibrillation or atrial flutter and controlling ventricular rate (in chronic atrial fibrillation or relapse of paroxysmal atrial arrhythmias), (2) the safety of sotalol, and (3) predictors of sotalol efficacy. Thirty-three patients, 28 with paroxysmal and five with chronic atrial fibrillation or atrial flutter, received an average dose of 265 +/- 119 mg of oral sotalol per day. During a 10 +/- 12 month follow-up, recurrence rate for paroxysmal arrhythmia was 64%, with a 50% recurrence at 4.6 months. For patients with chronic atrial fibrillation, ventricular rates were well controlled with sotalol administration (136 +/- 33 beats/min versus 88 +/- 23 beats/min; p = 0.04). No patient with chronic atrial fibrillation converted to sinus rhythm during the study. Side effects necessitated sotalol discontinuation in three patients. By multivariate analysis, younger age, higher ejection fraction, and absence of hypertension independently predicted sotalol efficacy.

Sotalol for atrial tachycardias after surgery for congenital heart disease

Atrial tachycardias, in particular atrial flutter after surgery for congenital heart disease, is associated with a high mortality. Treatment with various antiarrhythmic drugs and/or antitachycardia pacemakers is not very successful. Sotalol, a Class III drug, has shown to be a promising drug in adults with atrial tachycardias. However, the experience with sotalol in children after surgery for congenital heart disease is limited. Therefore, we describe our results here. Between December 1990 and February 1997, 26 children with atrial tachycardias, most of them with atrial flutter or fibrillation (n = 20), after surgery for congenital heart disease were treated with sotalol orally. The age of the children at the start of treatment was 7.5 +/- 5.8 years (mean +/- SD). The time interval between surgery and the start of atrial tachycardia ranged from 1 day to 14.3 years (3.8 +/- 3.8 years). Conversion to sinus rhythm was achieved in 16 out of 22 hemodynamically stable children with a dosage of 4.0 +/- 1.6 mg/kg per day. The six children without sinus rhythm on sotalol and four hemodynamically unstable patients were treated prophylactically with sotalol after DC cardioversion for their tachycardias. Two children complained of mild transient fatigue. Heart rate decreased during therapy (95 +/- 33 vs 81 +/- 21 beats/min; P = 0.01). QTc-intervals did not change. Proarrhythmias such as torsades de pointes were not encountered. Two children with a preexistent sick sinus syndrome showed aggravation of bradycardia and needed pacemaker implantation. The percentage of children with a recurrence-free interval of 1 and 2 years was 96% and 81%, respectively, for all atrial tachycardias, and 92% and 66% for atrial flutter. The recurrences of atrial tachycardias during the follow-up period, which ranged from 0.1-6.1 years (2.5 +/- 1.8 years) could be treated with only an increase of the dosage of sotalol in all but one patient. We conclude that sotalol is an effective drug for the treatment and prevention of atrial tachycardia in children after surgery for congenital heart disease.

Comparisons of oral propafenone and sotalol as an initial treatment in patients with symptomatic paroxysmal atrial fibrillation

The main goal of this study is to evaluate the safety and efficacy of propafenone versus sotalol as an initial choice of treatment in patients with symptomatic paroxysmal atrial fibrillation (AF), according to a double-blind randomized system. In the oral propafenone group (n = 41), 2 patients (5%) discontinued therapy because of gastrointestinal discomfort in 1 and dizziness in the other. Thirty-one (79%) of the 39 patients who continued the treatment had effective response to oral propafenone (>75% reduction of symptomatic arrhythmic attacks) on a mean dose of 663 +/- 99 mg/day with a decrease in attack frequency from 10 +/- 3 to 2 +/- 1 times per week. In the oral sotalol group (n = 38), 4 patients (11%) discontinued treatment because of dizziness in 2 and symptomatic bradycardia in 2. Twenty-six of the 34 patients (76%) who continued the treatment had effective response to oral sotalol on a mean dose of 200 +/- 57 mg/day with a decrease in attack frequency from 11 +/- 3 to 2 +/- 1 times per week. Comparisons of the results between propafenone and sotalol groups showed a similar incidence of intolerable (2 of 41 vs 4 of 38, p = 0.42) and tolerable side effects (10 of 39 vs 8 of 34, p = 1.0). The attack frequency at baseline (11 +/- 3 vs 10 +/- 4 times per week, p = 0.23) and after treatment (3 +/- 1 vs 3 +/- 2 times per week, p = 0.85) did not differ significantly between the 2 groups. The incidence of effective response to drugs was also similar (31 of 39 vs 26 of 34, p = 0.78). Furthermore, the decrease of symptom scores (-32 +/- 8% vs -29 +/- 7%, p = 0.18) and percentage decrease of ventricular rate (-15 +/- 4% vs -18 +/- 4%, p = 0.10) during AF were also similar between the 2 groups. In conclusion, oral propafenone and sotalol are equally effective and safe in preventing attacks and alleviating symptoms of paroxysmal AF.

Long-term management of atrial fibrillation

In the past decade, catheter ablation techniques and implantable devices have revolutionized the treatment of ventricular arrhythmias, junctional arrhythmias, and atrial flutter. For most patients presenting with atrial fibrillation (AF), the treatment available today is similar to that used a century ago, although nonpharmacologic strategies of therapy have begun to emerge for selected cases. There have been important recent advances in our understanding of the pathophysiology of AF and its complications, and it may be possible to improve patient management by refinement of the way in which current drugs are used.

Effect of electrode position on outcome of low-energy intracardiac cardioversion of atrial fibrillation

The aim of this study was to evaluate the new method of low-energy, catheter-based intracardiac cardioversion in patients with chronic atrial fibrillation (AF) and to compare 2 different lead positions. Accordingly, we prospectively studied 80 consecutive patients with chronic AF (9.8 +/- 7.9 months) who were randomly assigned to undergo internal cardioversion either via defibrillation electrodes placed in the right atrium and coronary sinus (coronary sinus group) or via defibrillation electrodes placed in the right atrium and left pulmonary artery (pulmonary artery group). Intracardiac shocks were delivered by an external defibrillator synchronized to the QRS complex. After conversion, all patients were treated orally with sotalol (mean daily dose, 189 +/- 63 mg/day). For conversion to sinus rhythm, the overall mean energy requirement was 5.6 +/- 3.1 J. In the coronary sinus group, cardioversion was achieved in 35 of 38 patients at a mean energy level of 4.1 +/- 2.3 J (range 1.0 to 9.9), and in the pulmonary artery group in 39 of 42 patients with 7.2 +/- 3.1 J (range 2.5 to 14.8). Although there was no difference with regard to success rate, the energy differed significantly between the 2 groups (p < 0.01). Mean lead impedance was 56.4 +/- 7.0 omega and 54.6 +/- 8.5 omega, respectively (p = NS). No serious complications were observed in either lead group. At a mean follow-up of 14.2 +/- 7.0 months, 54% and 56%, respectively, of patients who had been converted successfully remained in sinus rhythm. Thus, low-energy biphasic shocks delivered between the right atrium and coronary sinus or pulmonary artery are equally effective for cardioversion of patients with chronic AF. The energy requirements for conversion from a pulmonary artery electrode position are higher than for the coronary sinus position.

Pain threshold for low energy intracardiac cardioversion of atrial fibrillation with low or no sedation

Recent studies have shown that internal cardioversion of atrial fibrillation is safe and effective. In this randomized prospective study, we have tried to evaluate the influence of different waveforms on the perception of pain during internal cardioversion in patients with chronic atrial fibrillation.

METHODS

Internal cardioversion was performed with minimal or no sedation in 31 consecutive patients. R wave triggered, biphasic shocks of 6 ms/6 ms or 3 ms/3 ms duration (randomly selected) and approximately 65% tilt were used starting with a 50-V test shock. The shock intensity was increased in 40-V steps up to a maximum voltage of 520 V Shocks were applied via two custom-made catheters (Elecath, Rahway, NJ). In 16 patients (3 females, age 61 +/- 11 years, left atrium diameter 58 +/- 5 mm, duration of atrial fibrillation 4 +/- 4 months), 6/6 waveforms were used, and in 15 patients (1 female, age 62 +/- 5 years, left atrium diameter 59 +/- 4 mm, duration of atrial fibrillation 5 +/- 2 months), 3/3 waveforms were used. After cardioversion, each patient was asked to quantify their pain on a scale from 0-10 (0 = no pain, 10 = intolerable). Fourteen of the 15 patients in the 3/3 ms and 15 of the 16 patients in the 6/6 ms group were successfully cardioverted. Patients from the 6/6 waveform group were cardioverted with a lower mean voltage of 254/92 versus 355/127 V (P < 0.02), at lower pain score 1.8 +/- 1.3 versus 4.2 +/- 2.2 (P < 0.05) with equivalent energy (6.8 +/- 2.8 versus 6.2 +/- 1.5 J, n.s.) and required lower doses of midazolam of 2.2 +/- 1.9 versus 4.0 +/- 1.8 mg IV (P < 0.02). The waveform used in internal cardioversion seems to have a major impact on the patients' perception of pain. These results imply that energy determines the success of a shock, but voltage determines the pain perceived by the patient. The use of waveforms that deliver greater energy at lower peak voltages offers the possibility of internal cardioversion with less sedation and greater patient tolerance.

Prediction of outcome of electrical cardioversion by left atrial appendage flow velocities in atrial fibrillation

We evaluated the usefulness of left atrial appendage (LAA) flow velocity during atrial fibrillation as an objective measure for prediction of the outcome of electrical cardioversion. Left atrial appendage peak velocities were measured by transesophageal echocardiography before cardioversion in 56 patients. Left atrial thrombus was demonstrated in 6 (11%) of these patients. Cardioversion was then performed in the 50 patients who did not have a thrombus and in 1 patient whose left atrial thrombus disappeared after anticoagulant therapy (n = 51). Thirty-eight patients converted to sinus rhythm which remained stable until discharge (initial success group). Of these, long-term (> 6 months) maintenance of sinus rhythm was achieved in 31 patients (82%). Five patients with almost no detectable appendage contractions during atrial fibrillation were classified in the initial failure group. The peak LAA flow velocity was significantly higher in patients with the initial success group compared with the patients in the initial failure group (25.6 +/- 12.0 vs 15.3 +/- 10.7 cm/s, respectively; p < 0.01). Left atrial appendage flow velocity during atrial fibrillation may be useful for identifying candidates for electrical cardioversion.

Effectiveness of sotalol for atrial flutter in children after surgery for congenital heart disease

This study describes the efficacy of oral sotalol in the treatment and prevention of atrial flutter in children after surgery for congenital heart disease. In 11 of 13 children (85%), conversion to sinus rhythm was achieved, and in 8 of 11 within 24 hours.

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.

Pharmacologic control of heart rate in atrial fibrillation

Atrial fibrillation is associated with a resting heart rate in excess of age-matched subjects in sinus rhythm, and there is an additional steep rise in rate during exertion. This article reviews the factors responsible for this tachycardia, the pharmacologic agents commonly used for heart rate control, and the effects of atrial antiarrhythmic agents on the heart rate during paroxysmal atrial fibrillation.

Therapeutic strategies for atrial fibrillation. The value of decision analysis

In the absence of randomized, controlled trials of low-dose amiodarone in atrial fibrillation or a randomized, controlled trial of ventricular rate control versus antifibrillatory therapy, a Markov decision analysis is useful in comparing different therapeutic strategies for atrial fibrillation. The decision analysis described compared warfarin, quinidine, and low-dose amiodarone in patients with asymptomatic or minimally symptomatic chronic, persistent atrial fibrillation. This model suggests that electrical cardioversion followed by low-dose amiodarone is a relatively safe, effective alternative to long-term warfarin therapy.

The management of atrial fibrillation

Atrial fibrillation affects approximately one million persons in the United States, making it the most common cardiac arrhythmia seen in clinical practice. Its prevalence increases with age, and occurs in up to 10% of the population in the eighth decade of life. Unlike coronary heart disease, atrial fibrillation affects men and women approximately equally and, in an increasingly elderly population, will become an increasing burden to the health care system. The management of atrial fibrillation has undergone significant change in recent years. Large randomized controlled trials have shown that anticoagulation markedly reduces the risk of stroke, and a number of new antiarrhythmic agents are available for the restoration and maintenance of sinus rhythm. Furthermore, physicians have become more aware of the potential proarrhythmic side effects of all antiarrhythmic drugs. Finally, new procedures such as radiofrequency ablation of the atrioventricular junction and permanent pacing are playing increasing roles in the management of this arrhythmia. In this review, the identification of underlying causes and/or precipitating factors of atrial fibrillation, methods to control the ventricular response with atrioventricular nodal blocking drugs, the questions of whether restoration of sinus rhythm is a possible or desirable goal and how best to maintain sinus rhythm, should sinus rhythm be restored, and the importance of long-term anticoagulation with warfarin or antiplatelet therapy with aspirin are discussed.