Immediate Anticoagulation for Acute Stroke in Atrial Fibrillation
No, but ….
We all accept that full anticoagulation is highly effective, proven therapy for the great majority of patients with atrial fibrillation (AF) for the prevention of recurrent stroke. This controversy relates chiefly to the timing of anticoagulation in the acute stroke setting, the agent and mode of administration.
It is useful to track the path of the use of heparin over the past 25 years. Many of us based a practice of acute intravenous heparin in AF patients on the trial of the Cerebral Embolism Study Group (1983),1 which concluded that the immediate anticoagulation of embolic stroke was effective and apparently safe, yet based on only 45 randomized patients. Clearly, conclusions based on such small numbers would not be reached a quarter of a century later, where trial methodology is so much more sophisticated.
Two major influences then led to guidelines that immediate anticoagulation is not warranted. First, Sandercock and others, in much larger randomized trials, showed that there was a substantially lower risk of early recurrent embolism than previously thought.2,3,4 Second, these trials did show an overall benefit for a policy of acute anticoagulation. However, none of these trials used a monitored anticoagulation protocol. Interestingly, in an earlier heparin controversy in our series, we pointed out that there had been no adequate trial of APTT-monitored intravenous heparin in acute ischemic stroke. Sadly, as indicated by Chamorro, this remains the case.5 Furthermore, we are not convinced that there is bioequivalence between different anticoagulation agents and mode of administration.
So, what do we do in this evidence-light zone? In the great majority of patients with AF, we do not use full anticoagulation in any form in the acute stroke setting and would generally commence warfarin within a few days of symptom onset. In exceptional circumstances, such as recurrent embolism or echocardiographic evidence of left atrial or ventricular thrombus, we would immediately anticoagulate.
Our final word: the reality is that heparin is still widely used around the world in this setting. We don’t believe that this controversy will die without an adequately powered trial of monitored anticoagulation in high-risk patients with AF and acute stroke.
- Received July 10, 2006.
- Accepted August 11, 2006.
Cerebral Embolism Study Group. Immediate anticoagulation of embolic stroke: a randomized trial. Stroke. 1983; 14: 668–676.
Saxena R, Lewis S, Berge E, Sandercock PA, Koudstaal PJ. Risk of early death and recurrent stroke and effect of heparin in 3169 patients with acute ischemic stroke and atrial fibrillation in the International Stroke Trial. Stroke. 2001; 32: 2333–2337.
Berge E, Abdelnoor M, Nakstad PH, Sandset PM. Low molecular-weight heparin versus aspirin in patients with acute ischaemic stroke and atrial fibrillation: a double-blind randomised study. HAEST Study Group. Heparin in Acute Embolic Stroke Trial Lancet. 2000; 355: 1205–1210.