If you have AF and you’re taking warfarin, but are still unlucky enough to have an ischaemic stroke, then compared to people not on warfarin: –
You are likely to have milder effects from the stroke
You are less likely to die
Tell me about the study
The AnTicoagulation and Risk factors In Atrial fibrillation (ATRIA) study followed 13 559 adults with atrial fibrillation from Northern California. It was published in the medical journal “Stroke” (a highly regarded journal) in 2012.
It compared people taking warfarin with those not on anticoagulants, looking at how many strokes occurred and what their outcome was.
What were the results?
There were a total of 1025 ischemic strokes (the commonest kind, where a blood clot forms or gets lodged in an artery of the brain) and 299 intracranial hemorrhages.
Positive results about ischaemic stroke
1. Less likely to have a stroke
People taking warfarin had 60% of the risk of having a stroke compared to those not on anticoagulants. They had only 43% of the risk of having a fatal stroke.
2. Less risk of death
For those who had an ischemic stroke, people taking warfarin had only 64% of the risk of death within 30 days of the stroke, compared to people not on anticoagulants. And even better, those with an INR in the therapeutic range (2-3) had only 38% of the risk of death.
3. Milder effects
45.7% of people on warfarin were discharged from hospital with no deficits or only mild problems caused by an ischaemic stroke. This compared to 39.1% of people not on anticoagulants. This took into account age, sex, prior stroke, hypertension, heart failure, diabetes and coronary artery disease.
Negative results about haemorrhagic stroke
The problems were when the strokes were due to a brain bleed rather than a clot. Those on warfarin had 1.8 times the chance of having a brain bleed than those not on warfarin. The risk of death from a brain bleed was 1.62 times higher for those on warfarin than those not on anticoagulants. And more worrying, for those who had a high INR result of above 3, the risk of death was 2.66 times higher. For those who survived to be discharged from hospital, there was no difference in the deficit levels of those on warfarin and those not on anticoagulants.
What does this mean for me?
Like all statistics, the meaning is for groups of people rather than individuals. However this study reinforces the benefits of taking anticoagulants if you have atrial fibrillation and also highlights the importance of having regular INR tests if you are on warfarin, so that your INR can be kept in the therapeutic range.
What’s the study reference?
Margaret C. Fang, MD, MPH; Alan S. Go, MD; Yuchiao Chang, PhD; Leila H. Borowsky, MPH; Niela K. Pomernacki, RD; Natalia Udaltsova, PhD; Daniel E. Singer, MD