Efficacy of intravenous procainamide infusion in converting atrial fibrillation to sinus rhythm. Relation to left atrial size

Efficacy and safety of dronedarone versus placebo in patients with atrial fibrillation stratified according to renal function: Post hoc analyses of the EURIDIS-ADONIS trials

BACKGROUND

The use of antiarrhythmic drugs (AADs) in patients with chronic kidney disease (CKD) is complex because impaired renal clearance can cause increased drug levels, and risk of intolerance or adverse events. Due to the propensity for CKD to occur alongside atrial fibrillation/atrial flutter (AF/AFL), it is essential that AAD safety and efficacy are assessed for patients with CKD.

HYPOTHESIS

Dronedarone, an approved AAD, may present a suitable therapeutic option for patients with AF/AFL and concomitant CKD.

METHODS

EURIDIS-ADONIS (EURIDIS, NCT00259428; ADONIS, NCT00259376) were identically designed, multicenter, double-blind, parallel-group trials investigating AF/AFL control with dronedarone 400 mg twice daily versus placebo (randomized 2:1). In this post hoc analysis, the primary endpoint was time to first AF/AFL. Patients were stratified according to renal function using the CKD-Epidemiology Collaboration equation and divided into estimated glomerular filtration rate (eGFR) subgroups of 30-44, 45-59, 60-89, and ≥90 ml/min. Time-to-events between treatment groups were compared using log-rank testing and Cox regression.

RESULTS

At baseline, most (86%) patients demonstrated a mild or mild-to-moderate eGFR decrease. Median time to first AF/AFL recurrence was significantly longer with dronedarone versus placebo for all eGFR subgroups except the 30 to 44 ml/min group, where the trend was similar but statistical power may have been limited by the small population. eGFR stratification had no significant effect on serious adverse events, deaths, or treatment discontinuations.

CONCLUSIONS

This analysis suggests that dronedarone could be an effective therapeutic option for AF with an acceptable safety profile in patients with impaired renal function.

Electrical versus pharmacological cardioversion for emergency department patients with acute atrial fibrillation (RAFF2): a partial factorial randomised trial

BACKGROUND

Acute atrial fibrillation is the most common arrythmia treated in the emergency department. Our primary aim was to compare conversion to sinus rhythm between pharmacological cardioversion followed by electrical cardioversion (drug-shock), and electrical cardioversion alone (shock-only). Our secondary aim was to compare the effectiveness of two pad positions for electrical cardioversion.

METHODS

We did a partial factorial trial of two protocols for patients with acute atrial fibrillation at 11 academic hospital emergency departments in Canada. We enrolled adult patients with acute atrial fibrillation. Protocol 1 was a randomised, blinded, placebo-controlled comparison of attempted pharmacological cardioversion with intravenous procainamide (15 mg/kg over 30 min) followed by electrical cardioversion if necessary (up to three shocks, each of ≥200 J), and placebo infusion followed by electrical cardioversion. For patients having electrical cardioversion, we used Protocol 2, a randomised, open-label, nested comparison of anteroposterior versus anterolateral pad positions. Patients were randomly assigned (1:1, stratified by study site) for Protocol 1 by on-site research personnel using an online electronic data capture system. Randomisation for Protocol 2 occurred 30 min after drug infusion for patients who had not converted and was stratified by site and Protocol 1 allocation. Patients and all research and emergency department staff were masked to treatment allocation for Protocol 1. The primary outcome was conversion to normal sinus rhythm for at least 30 min at any time after randomisation and up to a point immediately after three shocks. Protocol 1 was analysed by intention to treat and Protocol 2 excluded patients who did not receive electrical cardioversion. This study is registered at ClinicalTrials.gov, number NCT01891058.

FINDINGS

Between July 18, 2013, and Oct 17, 2018, we enrolled 396 patients, and none were lost to follow-up. In the drug-shock group (n=204), conversion to sinus rhythm occurred in 196 (96%) patients and in the shock-only group (n=192), conversion occurred in 176 (92%) patients (absolute difference 4%; 95% CI 0-9; p=0·07). The proportion of patients discharged home was 97% (n=198) versus 95% (n=183; p=0·60). 106 (52%) patients in the drug-shock group converted after drug infusion only. No patients had serious adverse events in follow-up. The different pad positions in Protocol 2 (n=244), had similar conversions to sinus rhythm (119 [94%] of 127 in anterolateral group vs 108 [92%] of 117 in anteroposterior group; p=0·68).

INTERPRETATION

Both the drug-shock and shock-only strategies were highly effective, rapid, and safe in restoring sinus rhythm for patients in the emergency department with acute atrial fibrillation, avoiding the need for return to hospital. The drug infusion worked for about half of patients and avoided the resource intensive procedural sedation required for electrical cardioversion. We also found no significant difference between the anterolateral and anteroposterior pad positions for electrical cardioversion. Immediate rhythm control for patients in the emergency department with acute atrial fibrillation leads to excellent outcomes.

FUNDING

Heart and Stroke Foundation of Canada and the Canadian Institutes of Health Research.

Treatment of Acute Atrial Fibrillation: Ventricular Rate Control and Restoration of Sinus Rhythm

Atrial fibrillation (AF) is a familiar arrhythmia seen in the emergency department and the general population. In the past it was treated in the majority of cases by controlling the ventricular rate, whether the AF is acute or chronic. However, ventricular rate control alone does not address the underlying problem and the patients still remain in AF, cardiac output and symptoms have not been optimally corrected. There is definite risk of thromboembolism. Restoration of sinus rhythm is the only way of resuming the normal conduction physiology of the heart and correcting these problems This article provides a review of the two major principles of rhythm treatment of acute AF: rate control and restoration of sinus rhythm. Transthoracic electrical cardioversion is the mainstay of treatment in haemodynamically unstable AF, whereas in stable AF, there is a choice between rate control and restoration of sinus rhythm, or they can be carried out in conjunction with each other.

The Past, Present, and Potential Future of Sodium Channel Block as an Atrial Fibrillation Suppressing Strategy

Despite major advances in arrhythmia therapy, atrial fibrillation (AF) remains a challenge. A significant limitation in AF management is the lack of safe and effective drugs to restore and/or maintain sinus rhythm. The rational design of a new generation of AF-selective Na(+) channel blockers (NCBs) is emerging as a promising AF-suppressing strategy. Recent theoretical and experimental advances have generated insights into the mechanisms underlying AF maintenance and termination by antiarrhythmic drugs. Our understanding of antiarrhythmic drug-induced proarrhythmia has also grown in sophistication. These discoveries have created new possibilities in therapeutic targeting and renewed interest in improved NCB antiarrhythmic drugs. Recently described differences in atrial versus ventricular electrophysiology can be exploited in the prospective design of atrial-selective NCBs. Furthermore, state-dependent block has been shown to be an important modulator of NCB rate selectivity. Together, differential atrial-ventricular electrophysiological actions and state-dependent block form the backbone for the rational design of an AF-selective NCB. Synergistic combinations incorporating both NCB and block of K(+) currents may allow for further enhancement of AF selectivity. Future work on translating these basic research advances into the development of an optimized AF-selective NCB has the potential to provide safer and more effective pharmacotherapeutic options for AF, thereby fulfilling a major unmet clinical need.

Atrial fibrillation

Atrial fibrillation is the most common arrhythmia affecting patients today. Disease prevalence is increasing at an alarming rate worldwide, and is associated with often catastrophic and costly consequences, including heart failure, syncope, dementia, and stroke. Therapies including anticoagulants, anti-arrhythmic medications, devices, and non-pharmacologic procedures in the last 30 years have improved patients' functionality with the disease. Nonetheless, it remains imperative that further research into AF epidemiology, genetics, detection, and treatments continues to push forward rapidly as the worldwide population ages dramatically over the next 20 years.

Accelerated AV nodal conduction with use of procainamide in atrial fibrillation

BACKGROUND

Atrial fibrillation is a common dysrhythmia seen in the emergency department (ED). Chemical or electrical cardioversion may be performed on patients who have had atrial fibrillation for < 48 h duration and who are at low risk for thromboembolic events. Multiple studies suggest that intravenous procainamide is an appropriate agent in the treatment of acute atrial fibrillation due to its relatively low risk profile and high conversion rate.

OBJECTIVES

A case is presented that demonstrates an adverse reaction to the use of intravenous procainamide for chemical cardioversion of atrial fibrillation in an otherwise hemodynamically stable patient.

CASE REPORT

We report a case of lone paroxysmal atrial fibrillation in a patient with a structurally normal heart who suffered paradoxical accelerated atrioventricular nodal conduction and secondary hypotension in response to procainamide administration.

CONCLUSION

When administering procainamide for chemical cardioversion of atrial fibrillation, a low threshold should be maintained for administration of a complementary rate-controlling agent, and facilities for immediate electrical cardioversion always must be available.

Emergency department use of intravenous procainamide for patients with acute atrial fibrillation or flutter

OBJECTIVES

Acute atrial fibrillation and flutter are very common arrhythmias seen in emergency department (ED) patients, but there is no consensus for their optimal management. The objective of this study was to examine the efficacy and safety of intravenous (IV) procainamide for acute atrial fibrillation or flutter.

METHODS

This health records review included a consecutive cohort of ED patients with acute-onset atrial fibrillation or atrial flutter who received IV procainamide at one university hospital ED during a five-year period. The standard clinical protocol involved IV infusion of 1 g of procainamide over 60 minutes, followed by electrical cardioversion if necessary. A trained observer extracted data from the original clinical records. Outcome measurements included conversion to sinus rhythm, adverse events, and relapse up to seven days.

RESULTS

The 341 study patients had a mean age of 63.9 years (SD +/- 15.5 years), and 56.6% were male. The conversion rates were 52.2% (95% confidence interval = 47% to 58%) for 316 atrial fibrillation cases and 28.0% (95% confidence interval = 13% to 46%) for 25 atrial flutter cases. Mean dose given was 860.7 mg (SD +/- 231.2 mg), and median time to conversion was 55 minutes. Adverse events occurred in 34 cases (10.0%): hypotension, 8.5%; bradycardia, 0.6%; atrioventricular block, 0.6%; and ventricular tachycardia, 0.3%. There were no cases of torsades de pointes, cerebrovascular accident, or death. Most patients (94.4%) were discharged home, but 2.9% of patients returned with a recurrence of atrial fibrillation within seven days.

CONCLUSIONS

This study of acute atrial fibrillation or flutter patients treated in the ED with IV procainamide suggests that this treatment is safe and effective in this setting. Procainamide should be prospectively compared with other ED strategies.

A randomized, controlled trial of RSD1235, a novel anti-arrhythmic agent, in the treatment of recent onset atrial fibrillation

OBJECTIVES

The purpose of this study was to determine the efficacy and safety of intravenous RSD1235 in terminating recent onset atrial fibrillation (AF).

BACKGROUND

Anti-arrhythmic drugs currently available to terminate AF have limited efficacy and safety. RSD1235 is a novel atrial selective anti-arrhythmic drug.

METHODS

This was a phase II, multi-centered, randomized, double-blinded, step-dose, placebo-controlled, parallel group study. Fifty-six patients from 15 U.S. and Canadian sites with AF of 3 to 72 h duration were randomized to one of two RSD1235 dose groups or to placebo. The two RSD1235 groups were RSD-1 (0.5 mg/kg followed by 1 mg/kg) or RSD-2 (2 mg/kg followed by 3 mg/kg), by intravenous infusion over 10 min; a second dose was given only if AF was present. The primary end point was termination of AF during infusion or within 30-min after the last infusion. Secondary end points included the number of patients in sinus rhythm at 0.5, 1, and 24 h post-last infusion and time to conversion to sinus rhythm.

RESULTS

The RSD-2 dose showed significant differences over placebo in: 1) termination of AF (61% vs. 5%, p < 0.0005); 2) patients in sinus rhythm at 30 min (56% vs. 5%, p < 0.001); 3) sinus rhythm at 1 h (53% vs. 5%, p = 0.0014); and 4) median time to conversion to SR (14 vs. 162 min, p = 0.016). There were no serious adverse events related to RSD1235.

CONCLUSIONS

RSD1235, a new atrial-selective anti-arrhythmic agent, appears to be efficacious and safe for converting recent onset AF to sinus rhythm.

Conversion of recent-onset atrial fibrillation with intravenous amiodarone: a meta-analysis of randomized controlled trials

STUDY OBJECTIVE

To evaluate efficacy and safety of intravenous amiodarone for conversion of recent-onset atrial fibrillation.

DATA SOURCES

MEDLINE search of published, randomized, controlled trials assessing the efficacy and safety of intravenous amiodarone in recent-onset (< 7 days) atrial fibrillation, supplemented with searches of reference lists of identified articles and bibliographies of secondary and tertiary review articles.

STUDY SELECTION

The identified trials were eligible for meta-analysis if they met the following criteria: patients had recent-onset atrial fibrillation; patients were randomized to intravenous amiodarone, placebo, or another antiarrhythmic agent; no other antiarrhythmic agent except digoxin was administered simultaneously with intravenous amiodarone or other active treatments; the number and percentage of conversions to sinus rhythm after treatment began were reported; and the number and type of adverse drug reactions occurring after treatment began were reported.

RESULTS

Eighteen randomized controlled trials, including active control cohorts and placebo cohorts, met inclusion criteria. Atrial fibrillation was spontaneous in 13 trials, postoperative in 4, and combined spontaneous and postoperative in 1. A total of 550 patients received intravenous amiodarone, 451 received other antiarrhythmic therapy, and 202 received placebo. Unadjusted averages for cardioversion were as follows: intravenous amiodarone, 417 (76%) of 550 patients; other antiarrhythmics, 324 (72%) of 451 patients; and placebo, 121 (60%) of 202 patients. Pooled estimates of cardioversion for active cohort studies were 72.1% for intravenous amiodarone and 71.9% for other antiarrhythmics (p=0.84). Pooled estimates of cardioversion for placebo cohort studies were 82.4% for intravenous amiodarone and 59.7% for placebo (p=0.03). Unadjusted averages for adverse event rates were intravenous amiodarone, 94 (17%) of 550 patients; other antiarrhythmics, 63 (14%) of 451 patients; and placebo, 23 (11%) of 202 patients. Pooled estimates of adverse event rates for active cohort studies were 12.2% for intravenous amiodarone and 14.0% for other antiarrhythmics (p=0.64). Pooled estimates of adverse event rates for placebo cohort studies were 26.8% for intravenous amiodarone and 10.8% for placebo (p=0.02). The most common adverse drug reactions reported with intravenous amiodarone were infusion phlebitis, bradycardia, and hypotension.

CONCLUSION

The efficacy and safety profile of intravenous amiodarone is similar to that of other antiarrhythmics for cardioversion of recent-onset atrial fibrillation. Intravenous amiodarone is significantly more effective than placebo but is associated with significantly higher frequency of adverse events, although most were not considered to be dose limiting.

Pharmacologic conversion of atrial fibrillation: a systematic review of available evidence

This report reviews the efficacy of currently available antiarrhythmic agents for conversion of atrial fibrilation (AF) to normal sinus rhythm (NSR). A systematic search of literature in the English language was done on computerized databases, such as MEDLINE, EMBASE, and Current Contents, in reference lists, by manual searching, and in contact with expert informants. Published studies involving humans that described the use of antiarrhythmic therapy for conversion of AF to NSR were considered and only studies that examined the use of agents currently available in the United States were included. Studies exclusively describing antiarrhythmic therapy for conversion of postsurgical AF were excluded. The methodology and results of each trial were assessed and attempts were made to acquire additional information from investigators when needed. Assessment of methodological quality was incorporated into a levels-of-evidence scheme. Eighty-eight trials were included, of which 34 (39%) included a placebo group (level I data). We found in recent-onset AF of less than 7 days, intravenous (i.v.) procainamide, high-dose i.v. or high-dose combination i.v. and oral amiodarone, oral quinidine, oral flecainide, oral propafenone, and high-dose oral amiodarone are more effective than placebo for converting AF to NSR. In recent-onset AF of less than 90 days, i.v. ibutilide is more effective than placebo and i.v. procainamide. In chronic AF, oral dofetilide converts AF to NSR within 72 hours, and oral propafenone and amiodarone are effective after 30 days of therapy. We conclude than for conversion of recent-onset AF of less than 7 days, procainamide may be considered a preferred i.v. agent and propafenone a preferred oral agent. For conversion of recent-onset AF of longer duration (less than 90 days), i.v. ibutilide may be considered a preferred agent. For patients with chronic AF and left ventricular dysfunction, direct current cardioversion is the preferred conversion method. Larger, well-designed randomized controlled trials with clinically important endpoints in specific populations of AF patients are needed.

Pilsicainide for conversion and maintenance of sinus rhythm in chronic atrial fibrillation: a placebo-controlled, multicenter study

BACKGROUND

Pilsicainide is a newly synthesized antiarrhythmic agent with class Ic properties. Various antiarrhythmic agents have been used to convert atrial fibrillation (AF) to sinus rhythm or decrease the rate of relapse of AF.

METHODS

We randomly assigned 62 patients with chronic AF to oral treatment of either a placebo (10 patients) or 150 mg/day of pilsicainide (52 patients) for 4 weeks before electrical cardioversion. Before oral administration of pilsicainide, 41 patients underwent transesophageal echocardiography to investigate whether there was thrombus formation in the heart chambers. Patients without pharmacologic defibrillation underwent direct current cardioversion to restore sinus rhythm. After successful cardioversion, all patients continued to receive pilsicainide and were monitored for up to 2 years.

RESULTS

Before cardioversion, 11 patients in the pilsicainide group (21%) reverted to sinus rhythm. No patients in the placebo group reverted to sinus rhythm. Direct current cardioversion was performed in 51 patients; however, 8 patients were not converted to sinus rhythm (5 patients receiving pilsicainide, 3 patients receiving placebo), and 3 patients needed intracardiac cardioversion to convert to sinus rhythm. Asymptomatic bradyarrhythmias were observed in 5 patients in the pilsicainide group. During the follow-up period, 33 patients (71%) in the pilsicainide group remained in sinus rhythm at 1 month; this number decreased to 23 patients (49%) at 3 months, 20 (43%) at 6 months, 16 (34%) at 12 months, 16 (34%) at 18 months, and 16 (34%) at 24 months. All patients receiving placebo continued to receive placebo after the cardioversion, and AF recurred a few days after cardioversion in all cases. No independent discriminant variables were identified in the groups between maintenance and nonmaintenance of sinus rhythm. Although no serious side effects regarding pilsicainide have been documented, one patient died of acute myocardial infarction, most likely not related to pilsicainide administration.

CONCLUSIONS

Pilsicainide is effective in restoring or maintaining sinus rhythm in patients with chronic AF lasting longer than an average duration of 22 months. No major adverse effects were observed.

Cost-effective strategies in the acute management of atrial fibrillation

Atrial fibrillation is the most common sustained arrhythmia likely to be encountered in clinical practice. It is associated with significant morbidity and mortality. The treatment of patients with atrial fibrillation can be complex and costly, especially when patients are hospitalized for acute management of this arrhythmia. In this review, we summarize current approaches to the acute management of atrial fibrillation with an emphasis on the most cost-effective approaches. We review acute methods of heart rate control and cardioversion, including pharmacologic and other minimally invasive strategies. We believe that the most cost-effective approaches may require the use of standardized clinical pathways. This may help to ensure that patients with acute atrial fibrillation receive the most effective and efficient care.

Comparison of propafenone versus procainamide for the acute treatment of atrial fibrillation after cardiac surgery

A prospective, randomized, double-blind study to compare the efficacy in terminating postoperative atrial fibrillation of the class Ic drug propafenone versus class Ia drug procainamide was conducted. Intravenous propafenone was superior to procainamide in achieving rapid cardioversion and a better rate control with a lower incidence of symptomatic hypotension.

Dynamic effects of intravenous procainamide infusion on the electrophysiological properties during atrial fibrillation

Although the mechanism of atrial fibrillation (AF) is still controversial, multiple wandering reentry is considered the primary mechanism in most AF. It has been suggested that prolongation of the wavelength would make it impossible for the reentry to continue and would lead to the termination of the AF. In the present study a dynamic fluctuation in the electrophysiological properties was observed with procainamide infusion during AF. In 12 patients, both the local electrogram and monophasic action potentials (MAP) during AF were recorded from the right atrium before, during and after infusion of procainamide (10 mg/kg). The minimum AF cyclelength (CLmin), MAP duration at 90% repolarization (MAPD90) and widths of the intraatrial potentials (WAP) were measured with custom-made computer software. The conduction velocity index (CVI) was determined from the WAP. The wavelength index (WLI=CVIxCLmin) and postrepolarization refractoriness (PRR= CLmin-MAPD90) were calculated. In 6 patients, AF was terminated by procainamide infusion (group A), but not in the other 6 patients (group B). Group A patients showed a biphasic change in the parameters following procainamide infusion. In phase I, the CLmin, MAPD90 and PRR increased, while the CVI decreased, and the WLI remained unchanged. In phase II, the PRR, CVI and WLI increased and the AF was terminated. No restoration of the CVI nor increase in the WLI were observed in group B. The biphasic fluctuation in the CVI and the remarkable increase of the PRR and WLI were observed before termination of AF by procainamide infusion.

Ibutilide: an antiarrhythmic agent for the treatment of atrial fibrillation or flutter

OBJECTIVE

To discuss the clinical pharmacology of the antiarrhythmic drug ibutilide in patients with atrial fibrillation (AF) or atrial flutter (AFl).

DATA SOURCES

A MEDLINE search (January 1983-December 1997) was used to identify pertinent English-language articles on ibutilide. Key search terms included ibutilide, AF, AFl, cardioversion, and sinus rhythm. The MEDLINE search was supplemented by references included in the bibliographies of comprehensive review articles and studies.

STUDY SELECTION

Studies and review articles describing the chemistry, pharmacology, and pharmacokinetics of ibutilide were selected. All abstracts and published clinical trials evaluating the efficacy and safety were reviewed.

DATA EXTRACTION

Pertinent information on the pharmacology and mechanism of action of ibutilide was summarized. Data were extracted from the clinical trials describing trial design, patient population, interventions, methods of evaluation, outcomes, and statistical significance.

DATA SYNTHESIS

Ibutilide is a Vaughan-Williams class III antiarrhythmic agent approved for intravenous use for the rapid termination of recent-onset AF or AFl. The drug is extensively metabolized by the liver, has a volume of distribution of 11-15 L/kg, is 40% protein bound, and has an elimination half-life of 6 hours (range 2-12). Data from two placebo-controlled trials demonstrated the efficacy of ibutilide for converting AF or AFl of short duration (< or = 90 d) to normal sinus rhythm. A third placebo-controlled trial demonstrated efficacy in patients who developed AF or AFl following cardiac surgery. Comparative trials with procainamide and sotalol have shown at least similar and perhaps superior efficacy with ibutilide. There are no comparative trials with other antiarrhythmic drugs or with direct current cardioversion (DCC). In 586 clinical trial patients receiving ibutilide, the most significant adverse effect was the development of torsade de pointes in 25 patients (4.3%) including 10 cases (1.7%) in which the rhythm was sustained. All cases of torsade de pointes were terminated electrically and none resulted in death or severe morbidity. No prospective cost-effectiveness studies are available; however, results from two decision models suggest that ibutilide may have advantages over other drugs and first-line electrical cardioversion.

CONCLUSIONS

Ibutilide appears to be an effective alternative method for rapid conversion of recent-onset AF or AFl. The drug may be particularly useful in patients who have undergone recent cardiac surgery or those who are not ideal candidates for DCC. Although studies suggest that the risk of proarrhythmia and in particular torsade de pointes is relatively low, caution is advised until additional experience is gained in clinical practice.

Is there a future for antiarrhythmic drug therapy?

Drug therapy has traditionally been the mainstay of treatment for both ventricular and supraventricular arrhythmias. However, increasing knowledge about the potentially significant adverse effects of these medications, together with the emergence of new, nonpharmacological approaches to the treatment of arrhythmias, has led some to question the future of antiarrhythmic drug therapy. Antiarrhythmic drugs are quite effective in terminating a variety of arrhythmias, including atrioventricular (AV) node re-entrant and AV tachycardias (particularly calcium antagonists and adenosine), atrial flutter (class III agents) and atrial fibrillation (class IA and IC drugs. The chronic use of antiarrhythmic drugs has been increasingly limited by a fear of adverse effects (especially proarrhythmia) and the availability of highly effective nonpharmacological alternatives (particularly ablation for re-entrant tachycardias involving the AV node and bypass tracts and cardiovertor/defibrillators for malignant ventricular arrhythmias. Atrial fibrillation (AF) continues to be a therapeutic challenge for which there is no safe and curative nonpharmacological therapy. Antiarrhythmic drugs of classes IA, IC and III show efficacy in preventing recurrence of AF but there are concerns about possible pro-arrhythmic complications. In the future, antiarrhythmic agents will continue to be used acutely to terminate a broad range of sustained arrhythmias. Chronic use is likely to depend on the development of safer and/or more effective compounds, as well as on improved ways of predicting which patients are likely to develop pro-arrhythmic reactions. The development of molecular electrophysiology will allow for the identification of agents with selected ion channel blocking profiles which may prove efficacious with a lower risk of complications. Finally, an improved understanding of arrhythmia substrates may permit the identification of therapy that prevents arrhythmias by acting on the underlying substrate, rather than simply trying to modify the electrical end product.

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.

Intravenous propafenone for converting recent onset atrial fibrillation in emergency departments: a randomized placebo-controlled multicenter trial. FAPS Investigators Study Group

Atrial fibrillation (AF) is one of the most frequent dysrhythmias in patients coming to emergency departments (EDs), and pharmacological treatment is frequently performed. The aim of this randomized placebo-controlled multicenter trial was to compare propafenone (a class 1C antidysrhythmic agent), administered i.v. in the ED, with placebo in the treatment of recent-onset AF (<72 h). We randomly allocated 156 patients (88 males; 68 females) from 18 to 80 years old, with recent-onset AF, to receive i.v. propafenone (2 mg/kg for 10 min) or the matching placebo. The patients were followed for 2 h. Exclusion criteria were the presence of one of the following: lack of informed consent, clinical evidence of heart failure, clinical hyperthyroidism, recent acute myocardial infarction, atrioventricular block, cardiac valve dysfunction, a history of bronchial asthma, and current treatment with antidysrhythmic agents including digitalis. The two groups did not differ significantly in terms of sex, age, body weight, or estimated time elapsed since the beginning of atrial fibrillation. Conversion to sinus rhythm occurred in 13 of the 75 patients who received the placebo (17.3%) and in 57 of the 81 patients who were given propafenone (70.3%). In conclusion, intravenous propafenone administration in the ED can be considered a safe and effective approach for converting AF to sinus rhythm.

Conversion efficacy and safety of intravenous ibutilide compared with intravenous procainamide in patients with atrial flutter or fibrillation

OBJECTIVES

This multicenter study compared the efficacy and safety of ibutilide versus procainamide for conversion of recent-onset atrial flutter or fibrillation.

BACKGROUND

Ibutilide fumarate is an intravenous (IV) class III antiarrhythmic agent that has been shown to be significantly more effective than placebo in the pharmacologic conversion of atrial flutter and fibrillation to sinus rhythm. Procainamide is commonly used for conversion of recent-onset atrial fibrillation to normal sinus rhythm.

METHODS

One hundred twenty-seven patients (age range 22 to 92 years) with atrial flutter or fibrillation of 3 h to 90 days' (mean 21 days) duration were randomized to receive either two 10-min IV infusions of 1 mg of ibutilide fumarate, separated by a 10-min infusion of 5% dextrose in sterile water, or three successive 10-min IV infusions of 400 mg of procainamide hydrochloride.

RESULTS

Of the 127 patients, 120 were evaluated for efficacy: 35 (58.3%) of 60 in the ibutilide group compared with 11 (18.3%) of 60 in the procainamide group had successful termination within 1.5 h of treatment (p < 0.0001). Seven patients were found to have violated the protocol and were not included in the final evaluation. In the patients with atrial flutter, ibutilide had a significantly higher success rate than procainamide (76% [13 of 17] vs. 14% [3 of 22], p=0.001). Similarly, in the atrial fibrillation group, ibutilide had a significantly higher success rate than procainamide (51% [22 of 43] vs. 21% [8 of 38], p=0.005). One patient who received ibutilide, which was found to be a protocol violation, had sustained polymorphic ventricular tachycardia requiring direct current cardioversion. Seven patients who received procainamide became hypotensive.

CONCLUSIONS

This study establishes the superior efficacy of ibutilide over procainamide when administered to patients to convert either atrial fibrillation or atrial flutter to sinus rhythm. Hypotension was the major adverse effect seen with procainamide. A low incidence of serious proarrhythmia was seen with the administration of ibutilide occurring at the end of infusion.

Rhythm management in atrial fibrillation--with a primary emphasis on pharmacological therapy: Part 2

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 pharmacological conversion followed by maintenance of sinus rhythm by pharmacological (or occasionally ablative) therapies. This article will present current approaches to rate and rhythm control issues in AF. Part 1, published previously, dealt with rate control. Part 2, the current article, details approaches to the restoration of sinus rhythm by electrical and pharmacological means. The former may use transthoracic or catheter-based energy delivery systems. The latter may use intravenous or oral drug approaches. Part 3, to be published in a subsequent edition of PACE will deal with the maintenance of sinus rhythm.

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.

Comparison of right atrial and peripheral procainamide infusion levels in patients with spontaneous or induced atrial fibrillation

As part of a new effort to develop an implantable drug infusion/pacing system to treat atrial fibrillation, this study examined the effects of rapid intracardiac procainamide infusion in humans with pacing-induced atrial fibrillation. Twenty patients with atrial fibrillation for > 5 minutes during an EP study received 500 mg of procainamide either via a peripheral venous infusion (n = 5) or directly in the right atrium (n = 15). Peak coronary sinus and femoral vein procainamide blood levels (mean +/- SEM) during 10, 5, and 3.3 minute central infusions were 17.0 +/- 4.1, 25.1 +/- 4.5, 45.6 +/- 5.1 and 11.3 +/- 3.2, 17.1 +/- 6.4, 18.7 +/- 5.0, respectively. In contrast, peak coronary sinus and femoral procainamide levels following the 5 minute intravenous infusion were 17.7 +/- 5.1 and 9.3 +/- 2.1. Changes in QT, QTc, QRS, and RI intervals were similar at each infusion rate. Systolic blood pressures (BP) decreased more with higher procainamide infusion rates but similar when comparing intravenous versus central drug administration at the same rate. The mean +/- SEM decreases in blood pressure with the 10, 5, and 3.3 min procainamide infusions were 12f5, 20f11, and 39f14, respectively. Conversion to sinus rhythm was not a primary endpoint given the often transient nature of acute atrial fibrillation in this setting. We conclude that significantly higher femoral vein and coronary sinus procainamide levels can be achieved by central rather than peripheral drug infusion. These data support that concept that rapid central infusion of anti-arrhythmic therapy can result in high intracardiac levels of antifibrillatory agents for the treatment of paroxysmal atrial fibrillation.

Antiarrhythmic actions of intravenous ibutilide compared with procainamide during human atrial flutter and fibrillation: electrophysiological determinants of enhanced conversion efficacy

BACKGROUND

The selective class III antiarrhythmic agent ibutilide prolongs action potential duration and terminates atrial flutter (AFL) and fibrillation (AF), but the mechanism of its antiarrhythmic efficacy in humans has not been fully characterized. This study compared the antiarrhythmic effects of ibutilide with the class IA agent procainamide in humans during AFL and AF. Antiarrhythmic drug actions and electrophysiological characteristics of AFL and AF that enhanced pharmacological termination were investigated.

METHODS AND RESULTS

Right atrial monophasic action potentials were recorded during 148 episodes of AFL (n=89) or AF (n=59) in 136 patients treated with intravenous ibutilide (n=73) or placebo (n=22) as participants in randomized, double-blinded comparative studies or intravenous procainamide (n=53) in a concurrent open-label study. The conversion rates in AFL with ibutilide, procainamide, and placebo were 64% (29 of 45 patients), 0% (0 of 33), and 0% (0 of 11), respectively, whereas in AF the rates were 32% (9 of 28), 5% (1 of 20), and 0% (0 of 11), respectively. In AFL, ibutilide increased atrial monophasic action potential duration (MAPD) more (30% versus 18%, P<.001) and prolonged atrial cycle length (CL) less (16% versus 26%, P<.001) than procainamide. Ibutilide shortened and procainamide prolonged action potential diastolic interval during AFL (-12% versus 51%, P<.001). Ibutilide increased MAPD/CL ratio, whereas procainamide tended to decrease this ratio (13% versus -6%, P<.01). In AF, ibutilide and procainamide induced similar increases in atrial CL (48% versus 45%), but ibutilide induced a greater increase in MAPD (52% versus 37%, P<.05). Independent electrophysiological predictors of pharmacological arrhythmia termination were increase in MAPD/CL ratio (P=.005) in AFL and longer baseline mean MAPD (P=.011) in AF. Termination of AFL with ibutilide was characterized by significant increases in beat-to-beat atrial CL, MAPD, and diastolic interval variability. Ibutilide was significantly more effective in converting AF when the mean atrial CL was > or = 160 ms (64% versus 0%, P<.001) or MAPD was > or = 125 ms (57% versus 0%, P=.002) at baseline.

CONCLUSIONS

Enhanced conversion efficacy of ibutilide compared with procainamide in AFL is correlated with a relatively greater prolongation of atrial MAPD than atrial CL, and termination of AFL by ibutilide is characterized by oscillations in atrial CL and MAPD. Conversion of AF by ibutilide is enhanced by a longer baseline mean atrial CL or MAPD.

Intravenous Propafenone for Conversion of Atrial Fibrillation or Flutter to Sinus Rhythm: A Randomized, Placebo-controlled, Crossover Study

BACKGROUND: Propafenone has been claimed to be effective in converting atrial fibrillation and flutter to sinus rhythm; however, controlled clinical trials have reported variable results, and data about the safety of propafenone in the setting of heart failure are lacking. The aim of the present study was to evaluate the efficacy and safety of intravenous propafenone in converting atrial fibrillation and flutter to sinus rhythm. METHODS: Sixty patients with acute (<72 h) or chronic atrial fibrillation or flutter were included in a randomized, placebo-controlled, conditional cross-over study. Twenty eight patients, of whom 12 were in New York Heart Association class III and IV, had heart failure. Patients received intravenous propafenone (2 mg/kg in 10 minutes) and placebo subsequently at 1 hour intervals if sinus rhythm was not achieved. The patients' rhythms were continuously monitored for 1 hour and a 12-lead electrocardiogram, a 1-minute continuous rhythm strip and vital signs were recorded at baseline and at 15, 30, 45, and 60 minutes after the administration of each drug. RESULTS: Twenty of teh 59 patients (34%) treated with propafenone converted to sinus rhythm, while only 4 of the 50 patients (8%) treated with placebo converted (P <.001). Propafenone was more effective in patients with acute (<72 h) atrial fibrillation (64.5%). The conversion rate with propafenone was not significantly different from placebo in patients with atrial flutter and chronic atrial fibrillation (>72 h). Propafenone significantly decreased (P <.005 vs placebo) mean ventricular rate in nonresponders with a baseline heart rate of more than 100 beats/min. No clinically significant adverse effect occurred. CONCLUSIONS: We conclude that intravenous propafenone treatment is effective for converting acute atrial fibrillation; however, it seems unlikely to be beneficial in atrial flutter and chronic atrial fibrillation. Propafenone decreases ventricular rate in nonresponders, and a single dose of propafenone is relatively safe even in moderate-to-severe heart failure.

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.

Pharmacologic management of atrial fibrillation

In an era when many electrophysiologic problems are routinely treated with invasive procedures or implantable devices, drugs remain the cornerstones of treatment for atrial fibrillation. Atrial fibrillation may present as an episodic rhythm in patients who are primarily in sinus rhythm or it may be manifested as rhythm disorder that is permanent. Patients who appear to have an episodic rhythm disorder may be found to be in atrial fibrillation permanently when followed for long periods of time, and prognosis in the two forms is similar. It is, therefore, useful to consider them different manifestations in the same spectrum of disease. This review will address pharmacologic approaches designed to: (1) slow ventricular response; (2) restore sinus rhythm; (3) reduce occurrences of atrial fibrillation; and (4) prevent thromboembolic complications. Nonpharmacologic approaches to treating atrial fibrillation will be briefly reviewed.

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.

Role of echocardiography in the evaluation and management of atrial fibrillation

This article reviews the utility of transthoracic echocardiography and transesophageal echocardiography for patients with atrial fibrillation and focuses on evidence that these diagnostic techniques can aid in the achievement of these goals. Following a brief review of common findings from each of these techniques, the relevance of specific results to the management of atrial fibrillation is assessed.

Efficacy of ibutilide for termination of atrial fibrillation and flutter

The clinical utility of ibutilide fumarate (Corvert) for the acute conversion of atrial tachyarrhythmias to normal sinus rhythm has been demonstrated in several randomized, placebo-controlled clinical trials. The efficacy of intravenous ibutilide for rapid conversion of atrial flutter is in the range of 50-70%, whereas its efficacy for conversion of atrial fibrillation is 30-50%. Approximately 80% of atrial tachyarrhythmias that terminate do so within 30 minutes from the initiation of the intravenous infusion. Ibutilide is more effective than either intravenous procainamide or intravenous sotalol for conversion of atrial fibrillation and atrial flutter to sinus rhythm. Age, presence of structural heart disease, gender and concomitant medication do not appear to influence the efficacy of ibutilide; however, shorter duration of atrial fibrillation is a strong predictor of successful termination. Plasma concentration of ibutilide and QTc interval prolongation are not directly correlated with the success rate for conversion of atrial tachyarrhythmias. Ibutilide's greater efficacy compared with other antiarrhythmic drugs may be related to its ability to cause greater prolongation of atrial monophasic action potential duration relative to atrial cycle length. Termination of atrial flutter with ibutilide was preceded by increased atrial cycle length variability. Ibutilide rapidly and effectively converts atrial fibrillation and atrial flutter to sinus rhythm when administered as a 1-mg total dose followed by a second 1-mg dose. It should be used in conjunction with continuous electrocardiographic monitoring for at least 4 hours after the termination of the infusion, or until the QTc interval returns to baseline. Hypokalemia and hypomagnesemia should be corrected before the start of the infusion. An external cardiac defibrillator, intravenous magnesium, and an external transcutaneous cardiac pacemaker should be readily available for immediate use in the event that palymorphic ventricular tachyarrhythmias occur. Ibutilide is a new intravenous agent that safely and rapidly converts atrial fibrillation and atrial flutter to sinus rhythm.

Efficacy and safety of repeated intravenous doses of ibutilide for rapid conversion of atrial flutter or fibrillation. Ibutilide Repeat Dose Study Investigators

BACKGROUND

Currently available antiarrhythmic drugs have limited efficacy for acute termination of atrial fibrillation and flutter, especially if the arrhythmia is not of recent onset. The purpose of this multicenter study was to determine the efficacy and safety of repeated doses of intravenous ibutilide, a class III antiarrhythmic drug, in terminating atrial fibrillation or flutter.

METHODS AND RESULTS

Two hundred sixty-six patients with sustained atrial fibrillation (n = 133) or flutter (n = 133), with an arrhythmia duration of 3 hours to 45 days, were randomized to receive up to two 10-minute infusions, separated by 10 minutes, of ibutilide (1.0 and 0.5 mg or 1.0 and 1.0 mg) or placebo. The conversion rate was 47% after ibutilide and 2% after placebo (P < .0001). The two ibutilide dosing regimens did not differ in conversion efficacy (44% versus 49%). Efficacy was higher in atrial flutter than fibrillation (63% versus 31%, P < .0001). In atrial fibrillation but not flutter, conversion rates were higher in patients with a shorter arrhythmia duration or a normal left atrial size. Arrhythmia termination occurred a mean of 27 minutes after start of the infusion. Of 180 ibutilide-treated patients, 15 (8.3%) developed polymorphic ventricular tachycardia during or soon after the infusion. The arrhythmia required cardioversion in 3 patients (1.7%) and was nonsustained in 12 patients (6.7%).

CONCLUSIONS

Intravenous ibutilide given in repeated doses is effective in rapidly terminating atrial fibrillation and flutter and under monitored conditions is an alternative to current cardioversion options.

Electrophysiologic effects of a class I antiarrhythmic agent, cibenzoline, on the refractoriness and conduction of the human atrium in vivo

We investigated the effects of a class I antiarrhythmic drug, cibenzoline, on human atrial muscle in vivo. Electrophysiologic measurements were performed in 44 patients (mean age 49 +/- 15 years), before and after an intravenous infusion of cibenzoline 1.4 mg/kg in 5 min. Extrastimuli at a basic cycle length (BCL) of 500 ms were delivered from the right atrial appendage. The effective refractory period of the right atrium (ERP-A), the conduction time from the high right atrium to the coronary sinus, maximum conduction delay (Max. CD), repetitive atrial firing zone (RAFZ), fragmented atrial activity zone (FAAZ), and conduction delay zone (CDZ) were measured. Patients were divided into two groups according to whether repetitive atrial firing (RAF) was induced (group A, n = 18) or not (group B, n = 26). Cibenzoline increased ERP-A from 198 +/- 25 to 214 +/- 26 ms (p < 0.05) and decreased Max. CD from 55 +/- 23 to 43 +/- 19 ms (p < 0.05). There were significant decreases in the RAFZ (10 +/- 17 to 4 +/- 10 ms, p < 0.05), the FAAZ (20 +/- 25 to 12 +/- 18, ms p < 0.05), and the CDZ (41 +/- 21 to 32 +/- 19 ms, p < 0.05). Cibenzoline significantly increased ERP.A (186 +/- 25 to 212 +/- 26 ms, p < 0.05) in group A, but not in group B. There were significant decreases in the RAFZ [25 +/- 19 to 9 +/- 15 ms (p < 0.05) and FAAZ 22 +/- 29 to 11 +/- 21 ms, (p < 0.05)] in group A, but not in group B. The results suggest that cibenzoline can suppress paroxysmal atrial fibrillation by prolongation of ERP-A and may also have preferential effects on the substrate of atrial fibrillation and RAF.

Efficacy of intravenous ibutilide for rapid termination of atrial fibrillation and atrial flutter: a dose-response study

OBJECTIVES

Currently available antiarrhythmic drugs have limited efficacy for short-term, rapid termination of atrial fibrillation and atrial flutter.

BACKGROUND

Ibutilide fumarate is an investigational class III antiarrhythmic agent that prolongs repolarization by increasing the slow inward sodium current and by blocking the delayed rectifier current. It can be administered intravenously and has a rapid onset of electrophysiologic effects.

METHODS

The efficacy and safety of ibutilide were studied in 200 patients with atrial flutter > 3 h in duration or atrial fibrillation 3 h to 90 days in duration. Patients were randomized to receive a single intravenous dose of placebo or an infusion of ibutilide fumarate at 0.005, 0.010, 0.015 or 0.025 mg/kg body weight over 10 min. Conversion was defined as termination of the atrial arrhythmia during or within 60 min after infusion. Forty-one patients received placebo and 159 received ibutilide (0.005 mg/kg [n = 41], 0.010 mg/kg [n = 40], 0.015 mg/kg [n = 38] or 0.025 mg/kg [n = 40]).

RESULTS

The arrhythmia terminated in 34% of drug-treated patients. The rates of successful arrhythmia termination were 3% for placebo and 12%, 33%, 45% and 46%, respectively, for 0.005-, 0.010-, 0.015- and 0.025-mg/kg ibutilide. The placebo and 0.005-mg/kg ibutilide groups had lower success rates than all other dose groups (p < 0.05). The mean time to termination of the arrhythmia was 19 min (range 3 to 70) from the start of infusion. Successful arrhythmia termination was not affected by enlarged left atrial diameter, decreased ejection fraction, presence of valvular heart disease or the use of concomitant medications (beta-adrenergic blocking agents, calcium channel blocking agents or digoxin). Arrhythmia termination was not predicted by the magnitude of corrected QT interval prolongation but was associated with a shorter duration of atrial arrhythmia. The most frequent adverse events in ibutilide-treated patients were sustained and nonsustained polymorphic ventricular tachycardia (3.6%). All patients with sustained polymorphic ventricular tachycardia were successfully treated with direct current cardioversion and had no recurrence. The occurrence of proarrhythmia did not correlate with ibutilide plasma concentration.

CONCLUSIONS

These data demonstrate that ibutilide is able to rapidly terminate atrial fibrillation and atrial flutter.

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.

Effectiveness of intravenous propafenone for conversion of recent-onset atrial fibrillation: a placebo-controlled study

To evaluate the efficacy of propafenone in converting recent-onset atrial fibrillation (AF) lasting < 7 days, 182 patients were treated intravenously with propafenone (Group 1, n = 98) and with placebo 0.9% saline solution (Group 2, n = 84) in a double blind study. The treatment was continued until sinus rhythm (SR) was restored, but for no more than 24 h. Eighty-nine patients treated with propafenone (90.8%) and 27 patients treated with placebo (32.1%) responded to the treatment and SR was restored (p < 0.0005). The mean time for SR restoration was 2.51 +/- 2.77 h in Group 1, and 17.15 +/- 7.8 h in Group 2 (p < 0.0005). In both groups the patients in whom SR was not restored (nonresponders) had larger left atrial size and longer duration of AF than responders at the onset of the arrhythmia. Nonresponders in Group 1 showed a decrease in mean ventricular rate (MVR) from 143 +/- 16 to 101 +/- 18 (p < 0.0005), while in the nonresponders in Group 2 no reduction of MVR was observed. Two patients whose SR was restored with propafenone had sinus standstill lasting 3.4 and 3.8 s, respectively. Propafenone used intravenously is an effective, quick, and safe drug for treating AF. Moreover, it significantly reduces MVR in nonresponders.

Atrial fibrillation and flutter: maintaining stability of sinus rhythm versus ventricular rate control

Two major treatment strategies have emerged for managing atrial fibrillation: maintaining sinus rhythm by chronic administration of suppressive antiarrhythmic agents versus controlling the ventricular rate and chronic anticoagulation. Potential benefits of maintenance of sinus rhythm include improvement of the hemodynamic profile of the patient, a decreased risk of cerebrovascular accidents, reduced symptoms, and, if atrial fibrillation is successfully suppressed, possible elimination of the need for the chronic anticoagulation. When selecting long-term antiarrhythmic drug therapy for suppression of atrial fibrillation, it should be recalled that at least 50% of patients have a recurrence of the arrhythmia within the first year and the majority of other patients have a recurrence within the next 3 to 5 years. In addition, the risk of proarrhythmia and sudden cardiac death must be considered; this has stimulated interest in nonpharmacologic approaches to maintaining sinus rhythm. Large multicenter randomized trials are now under way to compare the benefits and risks of maintaining sinus rhythm versus controlling the ventricular rate and chronically anticoagulating patients in atrial fibrillation. Important endpoints of these trials include mortality, functional capacity, and quality of life.

Chemical cardioversion of atrial fibrillation with intravenous dofetilide

We studied the effects of two active dose levels of dofetilide (8 and 12 micrograms/kg) and placebo in 16 patients with recent onset atrial fibrillation. The study was of a crossover design such that all patients received a therapeutic agent, 15 patients completed the study. Cardioversion was achieved in 2/6 patients receiving 8 micrograms/kg dofetilide and in 2/9 patients receiving 12 micrograms/kg. No patients cardioverted as a result of the placebo infusion. Two patients who cardioverted suffered episodes of torsades de pointes following the active drug. Electrical cardioversion was attempted in eight patients who remained in atrial fibrillation and was successful in six. The average duration of atrial fibrillation was 35 days in those who cardioverted and 83 days in those who did not. The compound appears to have only limited effect in cardioversion of atrial fibrillation of moderate duration.

An approach to therapy of supraventricular tachyarrhythmias: an algorithm versus individualized therapy

Approaches to the treatment of supraventricular arrhythmias, including atrial fibrillation, atrial flutter, atrial tachycardia, atrioventricular (AV) reentrant tachycardia, and AV nodal reentrant tachycardia, continue to evolve. Within the past two decades, many new and effective treatments have become available. These include several new antiarrhythmic agents, ablative therapies, pacing and surgical modalities, and cardioversion/defibrillation techniques. This paper provides an algorithm for the treatment of these supraventricular arrhythmias which includes therapy for the acute episode as well as the prevention of subsequent episodes of the tachyarrhythmia.

The treatment of atrial fibrillation. An evaluation of drug therapy, electrical modalities and therapeutic considerations

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in clinical practice, and is responsible for considerable morbidity. Basic studies have shown that AF is usually due to the coexistence of multiple functional atrial re-entry circuits, and that the main determinant of its haemodynamic manifestations is the ventricular response rate. The major adverse clinical consequences of AF include palpitations, impaired cardiac function and thromboembolism. One approach to treating AF is to convert the patient's cardiac rhythm to sinus rhythm by direct current electrical cardioversion, which is initially successful in about 90% of cases. However, the AF recurrence rate over the year subsequent to cardioversion is very high, in the order of 75% in patients receiving no drug therapy. Class I and class III antiarrhythmic drugs reduce the rate of recurrence of AF, but at the expense of a variety of potential adverse effects including ventricular proarrhythmia. The latter is a rare effect (occurring in 1 to 2% of patients receiving most drugs), but can be lethal. A second approach to therapy is to leave the patient in AF, but to control the ventricular response rate and to prevent thromboemboli with oral anticoagulants. Disadvantages of this approach include the possibilities of functional limitations imposed by the arrhythmia, adverse effects of drug therapy, and major bleeding related to anticoagulation. New approaches currently under study include surgery to prevent AF from sustaining itself, implantable cardioverter devices to maintain sinus rhythm, and modification of AV nodal function by the induction of controlled radiofrequency injury.