The treatment of atrial fibrillation includes ventricular rate control, anticoagulation, conversion to normal sinus rhythm and maintenance of sinus rhythm. The choice of therapies that can achieve these goals is discussed in the text that follows. Some drugs are recommended here for indications that have not been approved by the FDA.

Atrial fibrillation increases the risk of stroke by a factor of 5. A randomized controlled trial (ACTIVE W) in 6706 patients with atrial fibrillation and one or more additional risk factors (≥75 years old; hypertension; previous stroke, transient ischemic attack or non- CNS embolus; left ventricular ejection fraction <45%; peripheral vascular disease; or 55-74 years old plus diabetes or coronary artery disease) found that a vitamin K antagonist such as warfarin (Coumadin, and others) was superior to clopidogrel (Plavix) plus aspirin in preventing vascular events, especially ischemic stroke.1

Now another study (ACTIVE A) from the same group of investigators has compared addition of clopidogrel to aspirin with aspirin alone in 7554 patients with atrial fibrillation and one or more additional risk factors for stroke. All of these patients were considered “unsuitable” for treatment with a vitamin K antagonist. Vascular events, primarily stroke, occurred significantly more often with aspirin alone. Major bleeding occurred significantly more often with aspirin plus clopidogrel.2

Oral anticoagulation with a vitamin K antagonist such as warfarin continues to be the treatment of choice for patients with atrial fibrillation and one or more additional risk factors for stroke.3-5 In patients who cannot or will not take a vitamin K antagonist, clopidogrel plus aspirin appears to be more effective in preventing stroke than aspirin alone.

1. ACTIVE Writing Group of the ACTIVE Investigators. Clopidogrel plus aspirin versus oral anticoagulation for atrial fibrillation in the Atrial fibrillation Clopidogrel Trial with Irbesartan for prevention of Vascular Events (ACTIVE W): a randomised controlled trial. Lancet 2006; 367:1903.

2. ACTIVE Investigators. Effect of clopidogrel added to aspirin in patients with atrial fibrillation. N Engl J Med 2009; 360:2066.

3. Antiplatelet and anticoagulant drugs. Treat Guidel Med Lett 2008; 6:29.

4. DE Singer et al. Antithrombotic therapy in atrial fibrillation: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition). Chest 2008; 133 (6 suppl): 546S.

5. AS Go. The ACTIVE pursuit of stroke prevention in patients with atrial fibrillation. N Engl J Med 2009; 360:2127.

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Arterial and venous thrombosis are major causes of morbidity and mortality. Arterial thrombi consist of platelet aggregates held together by small amounts of fibrin. Antiplatelet drugs are the drugs of choice for prevention and treatment of arterial thrombosis, but anticoagulants are also effective, and their effects can add to those of antiplatelet drugs. Venous thrombi are composed mainly of fibrin and trapped red blood cells, with relatively few platelets. Anticoagulants are the agents of choice for prevention and treatment of venous thromboembolism and for prevention of cardioembolic events in patients with atrial fibrillation.

Clopidogrel (Plavix - Sanofi-Aventis and Bristol-Myers Squibb), an oral thienopyridine that inhibits platelet aggregation, is now being advertised directly to the public on television. Clopidogrel is approved by the FDA for secondary prevention of myocardial infarction (MI), stroke and other vascular events and for use in patients with acute coronary syndrome (unstable angina or non-ST-elevation MI), including those undergoing angioplasty. It is used off-label for patients with ST-elevation acute MI