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©2013 UpToDate ® Print Email ACC/AHA/ESC guideline summary: Prevention of thromboembolism in patients with atrial fibrillation (AF) undergoing cardioversion Class I - There is evidence and/orgeneral agreement that the following approaches are effective for theprevention of thromboembolism in patients with AF undergoingcardioversion •  For AF duration of ≥48 hours or duration unknown, anticoagulation with a goal INR of 2.0 to 3.0 for at least three weeks before and four weeks after either electrical or pharmacologic cardioversion. •  For AF duration of more than 48 hours that requires immediate cardioversion due to hemodynamic instability: 1. Unfractionated heparin should be given concurrently (unless contraindicated) by an initial intravenous bolus followed by a continuous infusion at a dose adjusted to prolong the activated partial thromboplastin time to 1.5 to 2.0 times control. 2. Thereafter, oral anticoagulation with a goal INR of 2.0 to 3.0 for at least four weeks as in patients undergo elective cardioversion. 3. Limited data support the use of subcutaneous low molecular weight heparin. •  For AF duration less than 48 hours associated with hemodynamic instability (as manifested by angina, myocardial infarction, shock, or pulmonary edema), immediate cardioversion should be performed with delay for prior initiation of anticoagulation. Class IIa - The weight of evidenceor opinion is in favor of the usefulness of the following approachesfor the prevention of thromboembolism in patients with AF undergoingcardioversion •  During the 48 hours after the onset of AF, the need for anticoagulation before and after cardioversion may be based upon the patient's estimated risk of thromboembolism. •  A reasonable alternative to anticoagulation prior to cardioversion is transesophageal echocardiography to look for thrombus in the left atrium or left atrial appendage: 1. If thrombus is not identified, cardioversion is reasonable after initiation of unfractionated heparin (intravenous bolus followed by infusion at a dose adjusted to prolong the activated partial thromboplastin time to 1.5 to 2.0 times control). Limited data support the use of subcutaneous low molecular weight heparin for this indication. Heparin therapy is continued until oral anticoagulation with warfarin or other vitamin K antagonist has led to an INR ≥2.0.

1. If thrombus is not identified, cardioversion is reasonable after initiation of unfractionated heparin (intravenous bolus followed by infusion at a dose adjusted to prolong the activated partial thromboplastin time to 1.5 to 2.0 times control). Limited data support the use of subcutaneous low molecular weight heparin for this indication. Heparin therapy is continued until oral anticoagulation with warfarin or other vitamin K antagonist has led to an INR ≥2.0. Oral anticoagulation with a goal INR of 2.0 to 3.0 is continued for a total duration of anticoagulation of at least four weeks. 2. If thrombus is present, oral anticoagulation with a goal INR of 2.0 to 3.0 for at least three weeks before and four weeks after restoration of sinus rhythm; a longer duration of anticoagulation may be appropriate even if cardioversion is successful, because the risk of thromboembolism often remains elevated. •  For patients with atrial flutter undergoing cardioversion, anticoagulation according to the recommendations for AF. Data from: Fuster V, Ryden LE, Cannom DS, et al. ACC/AHA/ESC guidelines for the management of patients with atrial fibrillation. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing committee to revise the 2001 guidelines for the management of patients with atrial fibrillation). J Am Coll Cardiol 2006; 48:e149.