In patients with subclinical atrial fibrillation (AF) detected by implanted devices such as pacemakers or loop recorders, oral anticoagulation with apixaban resulted in a lower risk of stroke or systemic embolism than aspirin, but a higher risk of major bleeding in the ARTESIA study.
The results appear to contrast somewhat with the recently reported NOAH-AFNET 6 trial, which failed to show a reduction in stroke with the anticoagulant edoxaban vs placebo in a similar patient group, but that trial was stopped early and so was underpowered.
However, the lead investigators of both trials say the studies actually show consistent results — both found a lower rate of stroke than expected in this population, but the confidence intervals for stroke reduction with anticoagulation overlap, suggesting there is likely some effect, albeit less than that in clinical AF.
The big question is whether the reduction in stroke with anticoagulation outweighs the increase in major bleeding.
A new meta-analysis of the two trials showed that "oral anticoagulation with edoxaban or apixaban reduces the risk of ischemic stroke by approximately one-third and increases major bleeding by roughly double."
In absolute numbers, there were three fewer ischemic strokes per 1000 patient years with anticoagulation in the two trials combined, at the cost of seven more major bleeds.
