Cardioversion in atrial fibrillation. Focus on recent-onset atrial fibrillation

Atrial fibrillation is the most common sustained arrhythmia encountered in clinical practice. Its prevalence is rising due to an increasing elderly population and the improvement in management of life-threatening diseases such as myocardial infarction and heart failure. Over the past few years effective non-pharmacological treatments, new antiarrhythmics drugs, and anticoagulants have been introduced. Regardless of rate-control or rhythm control strategy, adequate stroke prevention still remains a cornerstone in the treatment of this arrhythmia. This review aims to illustrate the main practical issues in the management of atrial fibrillation, focusing on patients with recent-onset and hemodynamically stable atrial fibrillation.     

Cardioversion by internal electric shock of permanent atrial fibrillation

A new technique for cardioversion of chronic atrial fibrillation was used in 17 patients whose arrhythmia had resisted all attempts at electrical and pharmacologycal cardioversion. Atrial fibrillation was badly tolerated by all patients despite digitalis administered alone (8 patients) or combined with amiodarone (9 patients). Twelve patients had left atrial dilatation at echocardiography. The 200, 300 or 400 joule electrical shock was delivered between the proximal pole of a quadripolar catheter (cathode) and a back plate (anode). The catheter was positioned at the His bundle recording site then withdrawn into the right atrium. The internal shock restored sinus rhythm in 15 patients (88 p. 100). Transient atrioventricular block (3-315 sec) was observed in 8 patients. Eleven patients were discharged in sinus rhythm. In 4 patients, the atrial fibrillation recurred on day 8 and after 2, 4 and 9 months. A second shock was attempted in two patients and succeeded in one. After a mean follow-up period of 14.8 +/- 8 months (range 2 to 25 months), 8 of the 11 patients successfully cardioverted (72 p. 100) or of the attempted reductions (47 p. 100) were in sinus rhythm. The remaining 9 patients were treated with antiarrhythmic drugs (n = 5) or by his bundle catheter ablation (n = 4). High energy internal shock therefore seems to be an interesting treatment in patients with permanent atrial fibrillation after failure of external electric shock. It enabled 13 of the 17 patients in this series to avoid His bundle catheter ablation indicated by the quasi-impossibility to control the atrial rate and associated symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)     

Anticoagulation for atrial fibrillation in the elderly

Atrial fibrillation is a risk factor for stroke, particularly among elderly patients. Multiple trials have established that antithrombotic therapy decreases stroke risk. Aspirin is associated with a relative risk reduction of about 21% and adjusted-dose warfarin (international normalized ratio 2.0-3.0) is associated with a relative risk reduction of about 68%. Warfarin is more effective than aspirin but is used less often than indicated because of hemorrhagic risk and the inconvenience of coagulation monitoring. The oral direct thrombin ximelagatran has been investigated for stroke prevention in patients with atrial fibrillation in two large clinical trials. The results suggest efficacy in a fixed dose compared with well controlled warfarin. Although anticoagulation intensity was not monitored or regulated during treatment with ximelagatran, it was associated with less bleeding than warfarin. Other antithrombotic agents are under development as alternatives to warfarin, but sufficient data are not yet available to justify their clinical use in patients with atrial fibrillation.     

房间隔缺损并发心房纤颤患者应用Amplatzer伞封堵房缺后心房纤颤的电复律治疗

目的 :初步评价房间隔缺损并发心房纤颤患者应用 Am platzer伞封堵房间隔缺损后心房纤颤的电复律疗效。方法 :2例患者 （5 1～ 5 3岁 ）。在透视及食管超声心动图监视下经导管置入 Amplatzer伞封堵房间隔缺损。术后即时行超声心动图 ,术后 2 4h,和 1,3,6月 ,分别行经胸超声心动图评价房间隔缺损治疗效果。术后 6月行电复律。结果 :2例患者疗效均佳 ,房间隔未见残余分流 ,电复律成功 ,患者转为窦性心律 ,复律后无并发症及 Amplatzer伞移位。结论 :应用 Am platzer伞封堵房间隔缺损并发心房纤颤患者 ,电复律易成功 ,是一种安全有效的复律方法。     

Catheter ablation of atrial fibrillation in the elderly

Background Atrial fibrillation （AF） catheter ablation has emerged as a promising treatment strategy for AF, but has not been widely adopted in the elderly population. The present study aimed to determine the safety and efficacy of AF catheter ablation in the elderly popula-tion. Methods and Results The study population consisted of 316 patients with paroxysmal AF who underwent left atrial ablation. Ninety-five patients were≥65 years （48 males, mean age 68.9 ± 3.0 years old） and 221 patients were〈65 years old （130 males, mean age 52.5 ± 10.4 years old）. After a mean follow-up period of 34.0 ± 15.1 months, 55 （57.9%） patients in the elderly group were free from ar-rhythmia recurrence compared with 149 （67.4%） patients in the younger group （P=0.169）. Procedural complications were uncommon in both study groups. In logistic regression analysis, left atrial diameter （P=0.003）, hypertension （P=0.001）, dyslipidemia （P=0.039）, and coronary artery disease （P=0.018） were independent predictors of AF recurrence in the elderly population. Conclusions Catheter ablation of AF is safe and effective in older patients. Invasive strategies should be considered as an alternative choice in symptomatic elderly patients with AF.     

Predisposing factors for atrial fibrillation in the elderly

Atrial fibrillation (AF) in the elderly occurs as a consequence of cardiovascular aging and an age related increase of comorbidity. Several predisposing factors for AF have been identified for the overall AF population. Most of them, cardiovascular disease in particular, play a role in younger and older patients. The longer time period during which these risk factors can cause structural changes that ultimately lead to AF may, at least in part, explain the association between age and AF. In addition, less well defined age-related changes in cellular electrophysiologic properties and structure predispose to AF in the elderly.     

Anticoagulant use for atrial fibrillation in the elderly

OBJECTIVES: To determine the influence of advanced age on anticoagulant use in subjects with atrial fibrillation and to explore the extent to which risk factors for stroke and contraindications to anticoagulant therapy predict subsequent use. DESIGN: Retrospective cohort study. SETTING: The Veterans Affairs Boston Healthcare System. PARTICIPANTS: A total of 2,217 subjects with nonvalvular atrial fibrillation. MEASUREMENTS: Administrative databases were use to identify subject's age, anticoagulant use, and the presence of a diagnosis of atrial fibrillation, cerebrovascular accident, hypertension, diabetes mellitus, congestive heart failure, or gastrointestinal or cerebral hemorrhage. RESULTS: Unadjusted analysis showed no difference in warfarin use between those aged 75 and older and younger subjects regardless of the presence (33.9% vs 35.7%, P=.37) or absence (33.4% vs 34.7%, P=.58) of contraindications to anticoagulant therapy. Multivariate modeling demonstrated a 14% reduction (95% confidence interval (CI)=4-22%) in anticoagulant use with each advancing decade of life. Intracranial hemorrhage was a significant deterrent (odds ratio (OR)=0.27 95% CI=0.06-0.85). History of hypertension (OR=2.90, 95% CI=2.15-3.89), congestive heart failure (OR=1.70, 95% CI=1.41-2.04), and cerebrovascular accident (OR=1.54, 95% CI=1.25-1.89) were significant independent predictors for anticoagulant use. CONCLUSION: Despite consensus guidelines to treat all atrial fibrillation patients aged 75 and older with anticoagulants, advancing age was found to be a deterrent to warfarin use. Better estimates of the risk:benefit ratio for oral anticoagulant therapy in older patients with atrial fibrillation are needed to optimize decision-making.     

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

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

Long-term pharmacologic management of atrial fibrillation in the elderly

The first decision to be made in treating atrial fibrillation in the elderly is to determine whether to pursue a treatment strategy of rate control or rhythm control. Both strategies require use of anticoagulation therapy with warfarin (target international normalized ratio, 2.5; range 2–3). If a decision is made for rhythm control, the critical therapy is almost always with an antiarrhythmic drug. Before selecting an antiarrhythmic drug for use, it is first necessary to determine the presence or absence of underlying structural heart disease, as that will affect the available options for antiarrhythmic drug use. If there is no underlying structural heart disease, any of the available antiarrhythmic drugs may be used, although a clinically reasoned approach is suggested. If there is underlying structural heart disease, not all antiarrhythmic drugs are appropriate for use. A clinically reasoned approach is suggested in the presence of coronary artery disease, left ventricular dysfunction/congestive heart failure, or hypertension based largely on the risk/benefit profile of the drugs.     

Cardioversion of persistent atrial fibrillation by a combination of atrial specific and non-specific class III drugs in the goat

OBJECTIVE: In electrically remodeled atria the effect of blockers of the delayed rectifier K+ current I(Kr) on repolarization is reduced, whereas the efficacy of 'early' class III drugs (I(Kur)/I(to)/I(Kach) blockers) is enhanced. We evaluated the electrophysiological and antifibrillatory effects of AVE0118, dofetilide, and ibutilide (alone and in combination) on persistent atrial fibrillation (AF) in the goat. METHODS AND RESULTS: The effects of separate and combined administration of AVE0118, dofetilide, and ibutilide were determined before and after 48 h of AF. AVE0118 alone markedly prolonged the atrial refractory period (400 ms cycle length) (AERP(400)) before and after 48 h of AF. The prolongation of AERP(400) by dofetilide and ibutilide, respectively, was reduced by AF from 22+/-2 to 7+/-2 ms (p<0.01) and 25+/-5 to 5+/-2 ms (p=0.01). Pre-treatment with AVE0118 restored the prolongation of AERP(400) by dofetilide or ibutilide (to 20+/-3 and 30+/-6 ms; p<0.01). This effect was atrial specific since the QT-interval was not changed. The antifibrillatory action was evaluated in 10 goats that were in persistent AF for 57+/-7 days. Dofetilide (20 mug/kg/h) or ibutilide (4 mg/h) alone restored sinus rhythm in only 20% of the animals. AVE0118 (1, 3 and 10 mg/kg/h) [corrected] terminated AF in 11, 30, and 60%, respectively. Additional infusion of I(Kr) blockers caused an additional number of cardioversions, resulting in a final cardioversion rate of 56, 80, and 100%, respectively. AVE0118 alone prolonged the AF cycle length (AFCL) while the conduction velocity during AF (CV(AF)) remained unchanged (70+/-1 vs. 68+/-2 cm/s; p=0.3). Addition of dofetilide or ibutilide caused a synergistic increase in AFCL and a slight increase in CV(AF) to 74+/-1 cm/s (p<0.001). The length of the reentrant trajectories increased from 7.6+/-0.3 (control) to 11.6+/-0.5 cm after AVE0118 alone (p<0.001) and 14.8+/-0.8 cm after addition of dofetilide or ibutilide (p<0.001). CONCLUSIONS: In electrically remodeled atria, blockade of I(Kur)/I(to)/I(KAch) restored the class III action of I(Kr) blockers. Persistent AF could be effectively cardioverted by infusion of a combination of AVE0118 and dofetilide or ibutilide. This antifibrillatory action was associated with an almost twofold lengthening of the intra-atrial pathways for reentry.