Chest
Volume 119, Issue 1, Supplement, January 2001, Pages 194S-206S
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Antithrombotic Therapy in Atrial Fibrillation

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Study Design

During the last decade, many studies7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 assessingthe efficacy and safety of different antithrombotic therapies for theprevention of stroke in AF have been published (Tables 1234). The study designs will be briefly described, according to the type ofantithrombotic regimen studied.

Anticoagulation for Elective Cardioversion

Synchronized capacitor discharge was introduced by Lown andcoworkers65 for the rapid termination of atrial andventricular tachyarrhythmias. Systemic embolism is the most seriouscomplication of cardioversion and may follow direct current (DC), pharmacologic, and spontaneous cardioversion of AF.

AF

Bjerkelund and Orning66 performed a prospectivecohort study in which cardioversion without anticoagulants resulted ina 5.3% incidence of clinical thromboembolism, whereas a 0.8%incidence of thromboembolism was noted in patients receiving OACs.Although this was not a randomized study, the results are compellingbecause the patients receiving anticoagulants were also at higher riskthan those who were not. Several authors of caseseries52, 67, 68, 69, 70 also favor the use of

Atrial Flutter and Supraventricular Tachycardia

In several published series97, 98, 99, 100 of patientswho underwent cardioversion, all three arrhythmias (AF, atrial flutter, and supraventricular tachycardia) were pooled together when the datawere analyzed. Therefore, it is difficult to estimate the risk ofembolism during cardioversion for atrial flutter. However, there havebeen several reports50, 51, 97, 98, 99, 101 of embolization aftercardioversion of patients with pure atrial flutter. Patients atparticularly high risk include those with

Recommended Therapy

For patients with any high-risk factor or more than onemoderate-risk factor, we recommend warfarin (target INR 2.5; range, 2.0to 3.0). See chapter “Antithrombotic Therapy in Patients With Mechanical and Biological Prosthetic Heart Valves” for target INRs inpatients with mechanical heart valves. For patients with onemoderate-risk factor, we recommend aspirin, 325 mg/d, or warfarin(target INR 2.5; range, 2.0 to 3.0). For patients with no high-riskfactors and no moderate-risk factors, we recommend

AF

  • 2.1.1.

    We recommend that clinicians administer oral anticoagulanttherapy (target INR 2.5; range 2.0 to 3.0) for 3 weeks before and atleast 4 weeks after elective DC cardioversion of AF patients (grade1C+).

  • 2.1.2.

    Alternatively, we recommend that AF patients undergoanticoagulation then undergo TEE, and have cardioversion performedwithout delay if no thrombi are seen (grade 1C). For these patients, adjusted-dose warfarin therapy should still be continued until normalsinus rhythm has been maintained for at least

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