Question:

How long should you continue warfarin in a patient with paroxysmal atrial fibrillation?

12 October 2007 note: This question is over 2 years old and may differ to any new research.

We consulted a number of guidelines on atrial fibrillation which provide recommendations on initiation of antithrombotic agents based on a patient’s risk of developing a stroke.

The NICE guideline on atrial fibrillation states:

“1.5.3.1 Decisions on the need for antithrombotic therapy in patients with paroxysmal AF should not be based on the frequency or duration of paroxysms (symptomatic or asymptomatic) but on appropriate risk stratification, as for permanent AF (see section 1.8.6). B”

Appendix E in the guideline contains a copy of the stroke risk stratification algorithm. Section 1.8.5.2 discusses the risks of long-term anticoagulation therapy that need to be considered before anticoagulation therapy is initiated. One such risk factor is being over 75 years old.

However, the guideline states:

“The benefits of thromboprophylaxis in patients with AF are well established in randomised trials, and most guidelines recommend the use of anticoagulation with warfarin for high-risk patients. However, there continues to be wide variation in management. In particular, the elderly are at the highest risk of stroke, and would benefit most from  thromboprophylaxis. However, the elderly have more comorbidities and concomitant therapies that may preclude anticoagulant therapy. Also, most of the evidence on thromboprophylaxis has been based on hospital-managed populations and the application to primary care management and anticoagulation monitoring is still uncertain.”

“The most devastating complication associated with warfarin prophylaxis is the risk of intracranial haemorrhage, which is a particular problem in the elderly, in whom frailty, poor mobility, forgetfulness or poor compliance with medication, concomitant medications (resulting in drug interactions), and frequent falls may jeopardise the benefits from warfarin.
These factors are often cited as reasons for non-prescription of warfarin in the elderly, where the absolute benefit is likely to be greatest in view of their high risk.”

Most of the guidelines do not discuss ceasing warfarin therapy. The ACC/AHA/ESC practice guidelines on atrial fibrillation states:

“Chronic oral anticoagulant therapy in a dose adjusted to achieve a target intensity INR of 2 to 3 in patients at high risk of stroke, unless contraindicated. (Level of evidence: A)

“The need for anticoagulation should be reevaluated at regular intervals (Level of evidence: A )”

Unfortunately, the guideline does not appear to indicate the circumstances or criteria for stopping anticoagulant therapy in patients who have previously satisfied the criteria for initiating this therapy.


References
1. NICE guideline on atrial fibrillation. June 2006 (http://guidance.nice.org.uk/CG36)
2. ACC/AHA/ESC guidelines for the management of patients
with atrial fibrillation. 2001. (http://www.escardio.org/NR/rdonlyres/A3DC9139-3ECF-4F8B-8FE3-C83C7989DA28/0/atrialfibrillation.pdf)

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