CHICAGO (FRONTLINE MEDICAL NEWS) – The stroke risk in patients with recent-onset atrial fibrillation is similar to that of patients with longer-standing atrial fibrillation, according to a new secondary analysis of the landmark ARISTOTLE trial.

“Our key message is that patients with recent-onset atrial fibrillation had a similar risk of stroke but higher mortality than patients with remotely diagnosed atrial fibrillation, suggesting that patients with recently diagnosed atrial fibrillation are not at low risk and therefore warrant stroke prevention strategies,” Dr. Patricia O. Guimaraes said in presenting the findings at the annual meeting of the American College of Cardiology.

“Sometimes we as physicians hesitate in beginning oral anticoagulation therapy for patients that we just diagnosed. And of course patients are often afraid of anticoagulation therapy. But once they present with atrial fibrillation they are already at risk, and that’s why we need to anticoagulate them promptly,” added Dr. Guimaraes of the Duke Clinical Research Institute in Durham, N.C.

The benefits of apixaban (Eliquis) over warfarin seen in the overall randomized ARISTOTLE trial ( N Engl J Med. 2011; 365:981-92 ) were preserved in the recent-onset subset of the atrial fibrillation (AF) study population, she noted.

The rationale for this new post hoc analysis of ARISTOTLE is that virtually all of the evidence supporting anticoagulation for stroke prevention in AF is based on studies conducted in patients with permanent, persistent, or long-standing paroxysmal AF. Much less is known about stroke risk and the benefits of anticoagulation in patients with recent-onset AF, Dr. Guimaraes explained.

The 1,899 ARISTOTLE participants with AF onset within 30 days prior to enrollment comprised 10.5% of the total study population, all of whom had AF and at least one other stroke risk factor. The recent-onset subgroup was the same age as the 16,241 subjects in this analysis who had longer-standing AF, but the recent-onset group included a higher proportion of women, had a lower prevalence of CAD, and their cardiovascular risk factor profile differed from that of the remote-onset AF group.

The composite endpoint of stroke, systemic embolism, major bleeding, or all-cause mortality occurred at a rate of 8.69%/year in the recent-onset AF group, compared with 6.43%/year in the remote-onset group. However, in a multivariate regression analysis adjusted for potential confounders, the only significant differences in outcome between the two groups were in all-cause mortality – 5.15%/year in the recent-onset group, 3.15% in the remote-onset AF patients – and in the composite of stroke, systemic embolism, or all-cause mortality, which had an incidence of 6.46%/year in the recent-onset group, compared with 4.57%/year in remote-onset patients.

Turning to the impact of apixaban, Dr. Guimaraes noted that, as previously reported in the overall study, the primary endpoint of stroke or systemic embolism occurred in the apixaban group at a rate of 1.27%/year, compared with 1.6%/year with warfarin, for a 21% relative risk reduction in favor of the newer agent. She and her coinvestigators determined that in the remote-onset AF subgroup the relative risk reduction was 20%, while in the recent-onset subgroup the size of the effect was similar at 22%.

The composite safety endpoint of major or clinically relevant bleeding occurred in the remote-onset patients at a rate of 3.97%/year with apixaban versus 5.97%/year with warfarin, for a 33% relative risk reduction favoring the novel agent. In the recent-onset group, the rates were 5.04%/year with apixaban, compared with 6.4%/year with warfarin, for a 22% relative risk reduction.

Dr. Guimaraes observed an important limitation of this post hoc analysis is that the remote-onset AF group may have been selected for improved survival, since they didn’t die in the first 30 days after diagnosis.

Session co-chair Dr. Brian Olshansky commented that this analysis, which highlights the risks of recent-onset AF, argues for a strategy whereby a patient who presents to the ED with new-onset AF should get sent home on apixaban rather than being hospitalized for several days in order to be stabilized on warfarin.

“With recent-onset atrial fibrillation it’s going to take you several days to get anticoagulated with warfarin, whereas you’re immediately anticoagulated with apixaban,” said Dr. Olshansky, emeritus professor of internal medicine at the University of Iowa, Iowa City.

The ARISTOTLE trial was supported by Bristol-Myers Squibb and Pfizer. Dr. Guimaraes reported having no financial conflicts of interest.


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