Just one stroke risk factor signals anticoagulation need in AF

By Eleanor McDermid

The risk of stroke or systemic embolism is significantly increased in atrial fibrillation (AF) patients with just one risk factor apart from gender, say researchers.

Such patients benefitted from oral anticoagulation (OAC) therapy, even after accounting for the increased bleeding risk, report Gregory Lip (University of Birmingham, UK) and colleagues.

They say that this is in line with OAC recommendations in current European AF management guidelines; however, the most recent US guidelines (2014) specifically recommend OAC only in patients with at least two nongender risk factors, giving it only as an option for less high-risk patients.

Lip et al suggest that "treatment guidelines unduly focused on identifying high-risk AF patients" should reconsider their stance. "Indeed, strokes associated with AF are more likely to be fatal and disabling, and even 1 stroke risk factor confers a significant risk", they write in Stroke.

The team's findings were obtained in a real-world cohort of AF patients treated at the University Hospital of Tours, France, over a 10-year period. The annual rate of stroke/embolism among 616 non-anticoagulated patients with no CHA₂DS₂-VASc risk factors, besides gender in female patients, was 0.68%.

But the rate among 385 patients with one additional risk factor was 2.09%, giving a significant hazard ratio of 2.82 after accounting for aspirin (acetylsalicylic acid) use. The corresponding rates of death, stroke or embolism were 1.42% versus 5.59%, with a hazard ratio of 3.88.

And patients with one nongender risk factor benefitted from the addition of OAC, which reduced the annual rate of myocardial infarction significantly, from 1.63% to 0.65%, and the rate of ischaemic stroke nonsignificantly, from 1.08% to 0.91%.

The annual rates of intracranial haemorrhage and major extracranial bleeding were not significantly different between patients who did and did not receive OAC, tending, in fact, to be slightly lower in anticoagulated patients.

So overall there was a positive net clinical benefit, by two different methods of calculating it, although Lip et al note that OAC use could be a marker of better overall care in this nonrandomised community-based cohort.

"Thus, physicians should appreciate that even a single [non-gender-related] risk factor confers real risks of stroke/systemic thromboembolism/death, and OAC would reduce this overall risk", conclude the researchers.

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