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Volume 126, Issue 3, Supplement, September 2004, Pages 429S-456S
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Antithrombotic Therapy in Atrial Fibrillation: The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy

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This chapter about antithrombotic therapy in atrial fibrillation (AF) is part of the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S–187S). Among the key recommendations in this chapter are the following (all vitamin K antagonist [VKA] recommendations have a target international normalized ratio [INR] of 2.5; range, 2.0 to 3.0): In patients with persistent or paroxysmal AF (PAF) [intermittent AF] at high risk of stroke (ie, having any of the following features: prior ischemic stroke, transient ischemic attack, or systemic embolism, age > 75 years, moderately or severely impaired left ventricular systolic function and/or congestive heart failure, history of hypertension, or diabetes mellitus), we recommend anticoagulation with an oral VKA, such as warfarin (Grade 1A). In patients with persistent AF or PAF, age 65 to 75 years, in the absence of other risk factors, we recommend antithrombotic therapy with either an oral VKA or aspirin, 325 mg/d, in this group of patients who are at intermediate risk of stroke (Grade 1A). In patients with persistent AF or PAF < 65 years old and with no other risk factors, we recommend aspirin, 325 mg/d (Grade 1B). For patients with AF and mitral stenosis, we recommend anticoagulation with an oral VKA (Grade 1C+). For patients with AF and prosthetic heart valves, we recommend anticoagulation with an oral VKA (Grade 1C+); the target INR may be increased and aspirin added depending on valve type and position, and on patient factors. For patients with AF of ≥ 48 h or of unknown duration for whom pharmacologic or electrical cardioversion is planned, we recommend anticoagulation with an oral VKA for 3 weeks before and for at least 4 weeks after successful cardioversion (Grade 1C+). For patients with AF of ≥ 48 h or of unknown duration undergoing pharmacologic or electrical cardioversion, an alternative strategy is anticoagulation and screening multiplane transesophageal echocardiography (Grade 1B). If no thrombus is seen and cardioversion is successful, we recommend anticoagulation for at least 4 weeks (Grade 1B). For patients with AF of known duration < 48 h, we suggest cardioversion without anticoagulation (Grade 2C). However, in patients without contraindications to anticoagulation, we suggest beginning IV heparin or low molecular weight heparin at presentation (Grade 2C).

Section snippets

Results of a systematic review of randomized trials of oral vitamin K antagonist (VKA) therapy vs no antithrombotic therapy:

Investigators from the five primary prevention trials pooled their data after standardizing clinical definitions.6 The individual studies and their results are summarized in Tables 2345.1213141516 The results of individual-subject meta-analyses of these trials and later trials with pooled data are provided in Table 6. The clinical trials included patients with chronic persistent (also known as “sustained,” and including the category “permanent”17) or, less commonly, paroxysmal AF (PAF)

Recommendations

1.1.1. In patients with persistent (also known as “sustained,” and including patients categorized as “permanent” in certain classification schemes17) or paroxysmal (intermittent) AF at high risk of stroke (ie, having any of the following features: prior ischemic stroke, TIA, or systemic embolism, age > 75 years, moderately or severely impaired left ventricular systolic function and/or congestive heart failure, history of hypertension, or diabetes mellitus), we recommend anticoagulation with an

Recommendation

1.2. For patients with atrial flutter, we suggest that antithrombotic therapy decisions follow the same risk-based recommendations as for AF (Grade 2C).

Recommendations

1.3.1. For patients with AF and mitral stenosis, we recommend anticoagulation with an oral VKA, such as warfarin (target INR, 2.5; range, 2.0 to 3.0) [Grade 1C+].

1.3.2. For patients with AF and prosthetic heart valves, we recommend anticoagulation with an oral VKA, such as warfarin (Grade 1C+).

Remark: The target intensity of anticoagulation may be INR 3.0 (range, 2.5 to 3.5), ie, higher than the usual target INR of 2.5 (range, 2.0 to 3.0), and it may be appropriate to add aspirin, depending on

Recommendation

1.4. For AF occurring shortly after open-heart surgery and lasting > 48 h, we suggest anticoagulation with an oral VKA, such as warfarin, if bleeding risks are acceptable (Grade 2C). The target INR is 2.5 (range, 2.0 to 3.0). We suggest continuing anticoagulation for several weeks following reversion to NSR, particularly if patients have risk factors for thromboembolism (Grade 2C).

2.1 Anticoagulation for elective cardioversion of AF

Four decades have passed since synchronized capacitor discharge was first introduced by Lown and coworkers152153154 for the rapid termination of atrial and ventricular tachyarrhythmias. Systemic embolism is the most serious complication of cardioversion and may follow external or internal direct current (DC), pharmacologic, and spontaneous cardioversion of AF. Evidence favoring the efficacy of anticoagulation is based on observational studies. The large reported efficacy from such studies has

Recommendations

2.1.1. For patients with AF of ≥ 48 h or of unknown duration for whom pharmacologic or electrical cardioversion is planned, we recommend anticoagulation with an oral VKA, such as warfarin (target INR, 2.5; range, 2.0 to 3.0), for 3 weeks before elective cardioversion and for at least 4 weeks after successful cardioversion (Grade 1C+).

Remark: This recommendation applies regardless of a patient's risk factor status. Continuation of anticoagulation beyond 4 weeks is based on whether the patient

1.1 Atrial fibrillation

1.1.1. In patients with persistent (also known as “sustained,” and including patients categorized as “permanent” in certain classification schemes17) or paroxysmal (intermittent) AF at high risk of stroke (ie, having any of the following features: prior ischemic stroke, TIA, or systemic embolism, age > 75 years, moderately or severely impaired left ventricular systolic function and/or congestive heart failure, history of hypertension, or diabetes mellitus), we recommend anticoagulation with an

ACKNOWLEDGMENT

We are grateful to Margaret C. Fang, MD, MPH, for help reviewing the relevant literature and for reviewing early drafts of this chapter.

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    Copyright © 2004 The American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.