Comment
Author: Admin | 2025-04-28
Anticoagulated (for criteria and methods, see Prevention of thromboembolism) because conversion of atrial fibrillation, regardless of the method used, transiently increases the risk of thromboembolism.Synchronized cardioversion (200 joules biphasic, followed by 300 and 360 joules biphasic as needed) converts atrial fibrillation to normal sinus rhythm in approximately 90% of patients, although recurrence rate is high (2). Efficacy and maintenance of sinus rhythm after the procedure is improved with use of class Ia, Ic, or III antiarrhythmic medications during the 24 to 48 hours before the procedure. Cardioversion is more effective in patients with shorter duration of atrial fibrillation, lone atrial fibrillation, or atrial fibrillation with a reversible cause; it is less effective when the left atrium is enlarged (> 5 cm) or if a significant underlying structural heart disorder is present.Medications for conversion of atrial fibrillation to sinus rhythminclude class Ia (procainamide, quinidine, disopyramide), class Ic (flecainide, propafenone), and class III (amiodarone, dofetilide, dronedarone, ibutilide, sotalol, vernakalant) antiarrhythmics (see tableAntiarrhythmic Medications). A meta-analysis reported 4-hour, medication-specific cardioversion rates ranging from approximately 25% to 65%; the most effective agents were IV vernakalant, IV flecainide, IV propafenone, oral flecainide, and IV ibutilide (3). Excepting amiodarone and sotalol, which also slow ventricular response rate to atrial fibrillation, these medications should not be used until the rate has been controlled. The converting medications with oral formulations are also used for long-term maintenance of sinus rhythm (with or without previous cardioversion). A Cochrane review found antiarrhythmic medication efficacy ranged from 33% to 57%, with amiodarone being most effective (4). Nevertheless, antiarrhythmic medication for this purpose was associated with more adverse events, including mortality. For paroxysmal atrial fibrillation that occurs only or almost only at rest or during sleep when vagal tone is high, medications with vagolytic effects (eg, disopyramide) may be particularly effective. Exercise-induced atrial fibrillation may be better prevented with a beta-blocker.For certain patients with recurrent paroxysmal atrial fibrillation who also can identify its onset by symptoms, some clinicians provide a single oral loading dose of flecainide (300 mg for patients≥70 kg, otherwise 200 mg) or propafenone (600 mg for patients≥ 70 kg, otherwise 450 mg) that patients carry and self-administer when palpitations develop (“pill-in-the-pocket” approach) (5). This approach must be limited to patients who have no sinoatrial or AV node dysfunction, bundle branch block, QT prolongation, Brugada syndrome, or structural heart disease. Its major hazard (estimated at 1%) is the possibility of converting
Add Comment