Esmolol versus diltiazem in the treatment of postoperative atrial fibrillation/atrial flutter after open heart surgery

BACKGROUND: Supraventricular tachyarrhythmias are common after open heart surgery. Possible causative factors for these arrhythmias include operative trauma, atrial ischemia, electrolyte imbalances, pericardial irritation, and excess catecholamines. Two agents commonly used to control ventricular rate in atrial fibrillation or atrial flutter (AF/AFL) are beta-blockers and calcium channel blockers. METHODS AND RESULTS: This randomized study was designed to compare the safety and efficacy of intravenous diltiazem versus intravenous esmolol in patients with postoperative AF/AFL after coronary bypass surgery and/or valve replacement surgery. A comparative cost analysis was also performed. Thirty patients received either esmolol (n = 15) or diltiazem (n = 15) for AF/AFL. During the first 6 hours of treatment, 66.6% of esmolol-treated patients converted to sinus rhythm compared with 13.3% of the diltiazem-treated patients (P <.05). At 24 hours, 66.6% of the diltiazem group converted to SR compared with 80% of the esmolol group (not significant). Drug-induced side effects, time to rate control (<90 beats/min), number of patients requiring cardioversion, and length of hospitalization were similar for the two groups. The drug cost/successfully treated patient for esmolol versus diltiazem was $254 versus $437 at 6 hours and $529 versus $262 at 24 hours. CONCLUSIONS: Although this is a small study, it suggests that esmolol is more effective in converting patients to normal sinus rhythm than diltiazem during the initial dosing period. No differences in conversion rates were observed between the two groups after 24 hours. Additional studies are needed to confirm whether esmolol is the initial drug of choice in patients with postoperative AF/AFL after coronary bypass surgery.     

Intravenous flecainide versus verapamil for acute conversion of paroxysmal atrial fibrillation or flutter to sinus rhythm

In a single-blind randomized study, the efficacy of intravenous flecainide (2 mg/kg/10 minutes) versus verapamil (10 mg/1 minute) was assessed in 40 patients with paroxysmal atrial fibrillation (AF) or atrial flutter (AFI). The treatment was considered successful if sinus rhythm occurred within 1 hour. Of 20 patients receiving flecainide, 14 of 17 (82%) with AF converted to sinus rhythm, but in 3 patients with AFI flecainide failed. All patients treated with verapamil (17 AF, 3 AFI) showed lower ventricular rates after 1 hour; however, only 1 (6%) with AF converted to sinus rhythm and 1 (6%) converted to AFI. Patients who did not convert to sinus rhythm after treatment with verapamil were treated with flecainide and observed for another hour. After the change to flecainide, 9 of 15 patients (60%) with AF still converted. Thus, 23 of 32 patients (72%) with AF and none of 7 with AFI converted to sinus rhythm after treatment with flecainide. Conversion to sinus rhythm was achieved in 19 of 22 patients (86%) when AF lasted less than 24 hours and in 4 of 10 (40%) when the arrhythmia lasted greater than 24 hours. Transient adverse effects were noted in 10 patients (26%) after flecainide. In summary, flecainide is an effective and safe drug for conversion of paroxysmal AF to sinus rhythm, but ineffective for AFI. Verapamil appears to be of no use for conversion of AF or AFI to sinus rhythm.     

Risk of thromboembolism in acute atrial fibrillation or atrial flutter

Atrial fibrillation (AF) is the most common sustained cardiac dysrhythmia, predominating in the elderly, with stroke as a potentially devastating complication. Prevention of the thromboembolic sequelae from AF remains a central focus of practicing clinicians. Although the risk of thromboembolism in chronic AF is well recognized, less is known about the potential risk of systemic embolism in acute AF. In addition, recent data support the notion of a group at considerable risk of embolism from atrial flutter, an arrhythmia typically believed to bestow little increased risk of thromboembolism. The mechanism of thrombus formation, embolization, and resolution in atrial arrhythmias is not well defined, particularly in that of acute AF or atrial flutter. The traditional concept proposes that atrial thrombus forms only after > 2 days of AF and embolizes by being dislodged from increases in shear forces. This widely accepted concept further holds that newly formed atrial thrombus, in the setting of AF, organizes over a span of 14 days. The results of studies based on observations from transesophageal echocardiography examinations have provided provocative insight into the temporal sequence of atrial thrombus formation, embolization, and resolution in AF or atrial flutter and have expanded the traditional concept of thromboembolism in these atrial dysrhythmias. Namely, left atrial thrombus may form before the onset of AF in the face of sinus rhythm. Conversion to sinus rhythm may increase the thrombogenic milieu of the left atrium. Importantly, atrial thrombus may form in the acute phase of AF. Last, thrombi may require > 14 days to become immobile or to resolve. Findings similar to those of acute AF have been reported in patients with atrial flutter and coexisting cardiac pathology. On the basis of these emerging insights fostered by the use of transesophageal echocardiography, it appears appropriate to consider anticoagulation in patients presenting with acute AF or atrial flutter with coexisting cardiac pathology predisposing to left atrial thrombus.     

静脉地尔硫治疗快速房颤、房扑的疗效分析

为检验静脉地尔硫艹卓控制房颤、房扑心室率的有效性和安全性，对４７例快速房颤、房扑患者一次静脉注射０．２５ｍｇ／ｋｇ地尔硫艹卓后以５ｍｇ／ｈ～１０ｍｇ／ｈ微泵维持，平均起效时间５．２±２．７ｍｉｎ，总有效率９３．６％，心功能较用药前明显改善（Ｐ＜０．０５），对血压无明显影响，副作用发生率为１０．６％，均不严重。结果提示地尔硫艹卓是一种能迅速、安全、有效控制房颤、房扑患者心室率的药物     

Proarrhythmia in patients treated for atrial fibrillation or flutter.

OBJECTIVE: To review data on the type, mechanism, and prevalence of the proarrhythmic effect of drugs used to treat atrial fibrillation or flutter. DATA SOURCES: English-language literature from the early 1960s to the present was identified by manual search of the literature; relevant articles were reviewed. Pertinent earlier studies were identified from references in the articles reviewed and were included when relevant. STUDY SELECTION: All studies, controlled and uncontrolled, as well as individual case reports that contained data convincingly linking atrial antiarrhythmic therapy to a proarrhythmic side effect were included. DATA EXTRACTION: Key data were extracted from each article in studies in which a causal relationship between the use of a drug and a proarrhythmic response appeared likely. DATA SYNTHESIS: Antiarrhythmic therapy aimed at stabilizing the atrium may have adverse effects on the ventricle including torsade de pointes and, less commonly, sustained ventricular tachycardia. Different antiarrhythmic agents appear to have differing potentials for this proarrhythmic response, which is most common with class 1A agents. Other proarrhythmic responses to atrial antiarrhythmic agents include the acceleration of the ventricular response either by enhancing atrioventricular nodal or bypass tract conduction or by converting atrial fibrillation to flutter with 1:1 conduction. Calcium-channel blocking agents and, less commonly, digoxin may perpetuate the duration of paroxysmal atrial fibrillation, and virtually all agents can cause sinus node dysfunction or atrioventricular block. CONCLUSIONS: Although drug therapy for atrial fibrillation or flutter is generally well tolerated, the potential exists for uncommon but serious proarrhythmic effects. Knowledge of the risk factors and symptoms of these adverse reactions will help to further reduce this risk.     

Clinical evaluation in therapy of patients with atrial fibrillation or flutter

The weight of evidence clearly indicates that both atrial fibrillation and atrial flutter are due to a reentrant mechanism. Atrial fibrillation seems almost certainly due to multiple circulating reentrant wavelets of the leading circle type, whereas atrial flutter appears to be caused by single reentrant circuit located in the right atrium. The diagnosis of both atrial fibrillation and atrial flutter should always be possible using either old or new techniques. The interruption of atrial flutter should be possible using pacing or direct current cardioversion techniques, and the conversion of atrial fibrillation to sinus rhythm also is most often possible by direct current cardioversion or antiarrhythmic drug therapy. Long-term antiarrhythmic drug therapy to suppress recurrent atrial fibrillation and atrial flutter may be a problem, but availability of newer antiarrhythmic agents holds promise for finding an effective regimen. Catheter ablation techniques may be used to cause complete heart block in the treatment of either atrial fibrillation or atrial flutter when these rhythms cannot be satisfactorily suppressed and are associated with unacceptably rapid ventricular response rates. Finally, recent data suggest that atrial flutter may be successfully treated on a chronic basis with an antitachycardia pacing device, may be cured with catheter ablation techniques applied to a critical portion of the atrial flutter reentry circuit, and may be treated successfully with innovative surgical techniques. The latter is also true for atrial fibrillation.     

Positive atrial inotropic effect of dofetilide after cardioversion of atrial fibrillation or flutter

The pure class III agent dofetilide was evaluated to determine its effect on atrial function after cardioversion of atrial fibrillation or flutter. Compared with placebo, dofetilide-treated patients had evidence of better atrial function after cardioversion, indicating that this agent has a positive atrial inotropic effect during the period of postcardioversion atrial stunning.     

心房颤动与心房扑动的关系

心房颤动(atrial fibrillation，AF)是临床上最常见的持续性的心律失常。AF患者往往有心房扑动(atrial flutter，AFL)发作，而AFL患者也常伴有AF^[1-3]。在使用抗心律失常药物治疗过程中，AF可能变为AFL^[4-5]，或AFL蜕变为AF^[6-9]。这些现象提示二者在发生和维持机制上可能存在一些共性和相互关联。     

Early recurrence of arrhythmia in patients taking amiodarone or class 1C agents for treatment of atrial fibrillation or atrial flutter

Amiodarone use for the prevention of recurrent atrial fibrillation or atrial flutter requires drug loading over a period of several days to weeks, whereas class 1C agents do not. Three hundred thirty-nine patients were evaluated during drug loading with amiodarone or class 1C agents, and it was found that recurrent arrhythmia was common, usually not persistent, and frequently asymptomatic. Recurrent arrhythmia was not more common with amiodarone.