NOACs Now Seen as Go-to Anticoagulants for New-Onset Atrial Fibrillation

Patrice Wendling

February 16, 2017

LEIDEN, THE NETHERLANDS — A new study suggests novel oral anticoagulants (NOACs) have overtaken vitamin K antagonists (VKAs) for the treatment of newly diagnosed atrial fibrillation, although a disturbing number of patients are still not on appropriate stroke preventive therapy[1].

"There's a shift that the majority of patients get NOACs, and in our registry almost 90% are prescribed by cardiologists," lead author Dr Menno V Huisman (Leiden University Medical Center, the Netherlands) told heartwire from Medscape.

The study was published in the February 21, 2017 issue of the Journal of the American College of Cardiology.

To heartwire , Dr John H Alexander (Duke Clinical Research Institute, Durham, NC) who was not involved in the study, commented, "One of the concerns we've had is that there's been relatively slow adoption of NOACs, and this GLORIA-AF data suggest that we're making progress. But I do think it's sort of a best-case scenario; they're obviously selected centers at a selected time and selected patients."

The Global Registry on Long-term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation (GLORIA-AF) investigators compared data from 1063 patients in phase 1 of the prospective registry with 15,092 patients enrolled in phase 2 from  after approval of the first NOAC, dabigatran (Pradaxa, Boehringer Ingelheim). Other NOACs in the analysis were rivaroxaban (Xarelto, Bayer Pharma/Janssen Pharmaceuticals), apixaban (Eliquis, Bristol-Myers Squibb/Pfizer), and edoxaban (Savaysa/Lixiana, Daiichi Sankyo).

Phase 2 patients (median 71 years; 45.5% female) had a mean CHA2DS2-VASc score of 3.2, and hypertension was the most common comorbidity, present in 74.6%. Enrollment was from November 2011 to December 2014 in 44 countries (Europe 47.1%; North America 22.5%; Asia 20.3%), typically at university hospitals (33.7%) or specialist offices (30.3%). Patients with mechanical heart valves, previous VKA therapy for >60 days, and AF due to a reversible cause are excluded from the ongoing registry.

In the post-NOAC era, 79.9% of patients received oral anticoagulants, of which 47.6% were NOACs (dabigatran in 31.6%, other NOACs 16.0%). Another 32.3% of patients received VKAs, 11.3% aspirin (acetylsalicylic acid), 0.8% other antiplatelet agents, and 7.8% no antithrombotic therapy.

In contrast, 32.8% of AF patients during the pre-NOAC era received VKAs, 41.7% aspirin, and 20.2% no therapy.

"There's an important message that aspirin is still used, not so much in Europe because we are sticking to the European guidelines, but in North America, especially the United States, it's still prevalent. And what is important is that aspirin has no role in the prevention of stroke in atrial fibrillation," Huisman said.

In an accompanying editorial[2], Dr Prakash Deedwania (University of California San Francisco) and Dr Tushar Acharya (National Heart, Lung, and Blood Institute, Bethesda, MD) write that the overall findings are not that surprising, given the many advantages of NOACs, but that "perhaps the more important and disturbing finding is that nearly 20% of AF patients are not on appropriate stroke preventive therapy."

While some readers who take the "glass half-full" point of view may be encouraged by the 80% coverage, they caution that this high rate is not consistent with other contemporary registries that have shown oral anticoagulant use to be more in the 50% range, including the PINNACLE registry at 44.9%.

The editorialists also suggest that the enrolled cohort is not representative of most AF patients in the general population and question why sites from the low-resource setting of Africa were reported to have an 87.4% OAC compliance rate and only 1.5% of patients not on treatment vs corresponding rates of 78.3% and 7.5% in North America.

They also point out that there was minimal overlap between patient populations in phase 1 and phase 2, with 67.1% of patients from China and 8% from North America in phase 1, suggesting that any comparison of OAC between the two phases may represent geographical rather than temporal variation.

They conclude: "Let us not be lulled into a false sense of security. More representative data are needed to get realistic estimates of where we stand in terms of OAC use for stroke prevention in AF."

Alexander told heartwire that to improve OAC treatment rates, there needs to be more attention on making good anticoagulation a quality focus and less time spent comparing NOACs with each other, "which is a total waste of time.

"They're all better than warfarin, and all of them plus warfarin are better than aspirin, and all of that is better than nothing. The real advantage of the NOACs is getting more patients with afib who are at risk to be treated with oral anticoagulation," he added.

GLORIA-AF was funded by Boehringer Ingelheim. Huisman has received honoraria for presentations as well as research grants from Boehringer Ingelheim, Bayer Healthcare, Pfizer/Bristol-Myers Squibb, GlaxoSmithKline, Aspen, and Actelion Pharmaceuticals. Disclosures for the coauthors are listed in the paper. Alexander reported research funding from and serving as a consultant for Boehringer Ingelheim and Bristol-Myers Squibb/Pfizer. Deedwania and Acharya reported no relevant financial relationships.

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