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 versus 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 AFib.
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 1,000 patient-years with anticoagulation in the two trials combined, at the cost of seven more major bleeds.
The lead investigators of the two trials have somewhat different opinions on how these findings may translate into clinical practice.
Jeff Healey, MD, Population Health Research Institute, McMaster University, Hamilton, Ont., lead investigator of the ARTESIA trial, believes that the risks and benefits need to be assessed in individual patients, but there should be some patient groups that will benefit from anticoagulation treatment.
“In patients with pacemakers or implantable loop recorders with continuous monitoring, subclinical AF[ib] is detected in about one third of patients, so this is extremely common,” he said in an interview. “The question is whether this is just a normal feature of getting older or is this like AF[ib] that we see in the clinic which increases stroke risk, and I think we can conclude from ARTESIA that this subclinical AF[ib] is associated with an increased risk of stroke, although that is lower than the risk with clinical AF[ib], and that it can be reduced by anticoagulation.”
Until recently it hasn’t been possible to quantify the risk associated with subclinical AFib, he noted. “But now we have a rich dataset to use to see if we can tease out some specifics on this. Future analyses of this dataset will help define patients where the benefits outweigh the risks of bleeding. For now, I think we can look at the data in a qualitative way and consider the totality of risk factors in each patient – their bleeding risk, stroke risk, how much AF[ib] they have, and make a decision as to whether to give anticoagulation or not.”
But Paulus Kirchhof, MD, University Heart and Vascular Center Hamburg (Germany), lead investigator of the NOAH-AFNET 6 trial said: “Both trials showed the stroke rate is low in these patients – about 1% per year – and that anticoagulation can reduce it a bit further at the expense of increasing major bleeding. I don’t believe the AF[ib] episodes picked up on these devices constitute a sufficient stroke risk to warrant anticoagulation, given the bleeding risk.”
Dr. Kirchhof suggests an alternate approach of performing further traditional AFib monitoring on these patients.
“I think going forward in my practice, when we come across this device-detected AF[ib], we will do further investigations with an established method for detecting AF[ib] involving surface ECG monitoring – maybe a 3-day or 7-day Holter. If that shows AF[ib], then we will be on firm ground to start anticoagulation. If that doesn’t show AF[ib], we will probably not use anticoagulation.”
The ARTESIA trial and the meta-analysis of the two trials were both presented at the annual scientific sessions of the American Heart Association. Both studies were also simultaneously published online – ARTESIA in the New England Journal of Medicine and the meta-analysis in Circulation.