"When can I stop my warfarin?" This is a common question from patients with atrial fibrillation (AF) who have had normal sinus rhythm restored by cardioversion or medications. The correct answer is a subject of debate, but from the patient's perspective, stopping sooner rather than later is always preferable. Unfortunately, that approach may not be in their best interest, as determined by the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study. This study was designed to investigate 2 strategies of treatment for AF, rate control and rhythm control. Warfarin treatment was included in both strategies, although patients in the rhythm control group could stop their warfarin after 4 weeks of control with antiarrhythmic drugs.
The investigators assessed occurrence and characteristics of strokes in both treatment groups. A number of variables were analyzed for their relationship to ischemic stroke, including age, gender, history of stroke, diabetes, hypertension, smoking, and coronary artery disease. Eighty-four percent of the rate control group and 52% of the rhythm control group continued anticoagulation throughout the study. Strokes occurred in 8.2% of patients, most of which were ischemic in nature (6.3%). Several variables were associated with increased risk. These included advancing age, female gender, an initial episode of AF lasting 2 or more days, diabetes, and a history of previous stroke or transient ischemic attack. The presence of AF was associated with a 60% increased risk of ischemic stroke. The use of warfarin was associated with a 69% decrease in stroke risk.
The authors of the study concluded that warfarin offers benefits not only for patients with AF, but also for those whose rhythm is presumably controlled. They suggest continuing therapy indefinitely in patients who have a history of AF and high stroke risk.
Dr. Garrett is a clinical pharmacist practitioner at Cornerstone Health Care in High Point, NC.
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