Oral Anticoagulants Remain Underused in US for Atrial Fibrillation: PINNACLE Registry

Pam Harrison

March 21, 2016

CHICAGO, IL — Oral anticoagulants (OACs) are deeply underused for stroke prevention in US patients with atrial fibrillation, even those considered to be at the highest risk of stroke, according to figures in an ongoing national quality-improvement registry[1].

About 24% of the almost 430,000 patients in the analysis were not prescribed any form of antithrombotic therapy, including antiplatelets. Prescriptions of an oral anticoagulant went up with stroke risk scores, but prevalence of such prescriptions was only as high as 50% even among patients in the highest stoke-risk categories—those with a CHADS2 score of 3 or a CHA2DS2-VASc score of 5, according to the authors, led by Dr Jonathan C Hsu (University of California, San Diego), in their report published March 19, 2016 in JAMA Cardiology.

"We knew based on previous data that prescription patterns were low across the US in regard to the use of oral anticoagulants to reduce stroke risk in AF patients, but we assumed that rates had probably improved, given more guideline updates and more options with the newer oral anticoagulants" Hsu told heartwire from Medscape.

"Unfortunately, our study did not find what we had hoped—namely, that prescribing rates had increased," he added.

"So despite the fact that we have several options to choose from now, and despite our experience with and knowledge of the fact that these drugs do reduce the risk of stroke, we still have much room for improvement."

Other research has highlighted another part of the equation, that even among patients with AF who are prescribed oral anticoagulants, nearly half don't take them or acceptably adhere to them.

The current analysis "makes an important contribution and helps highlight that significant opportunity to improve care exists among many outpatient practices," write Dr Jonathan Piccini Sr (Duke University Medical Center, Durham, NC) and Dr Gregg Fonarow (University of California, Los Angeles) in an accompanying editorial[2]. "However, it is now critical to move beyond documenting these quality gaps to implementing meaningful and effective quality improvement."


The researchers looked at data on antithrombotic therapy from the National Cardiovascular Data Registry Practice Innovation and Clinical Excellence (NCDR-PINNACLE) registry in 429,417 patients with AF, with a focus on usage across different stroke-risk strata. Their mean CHADS2 score was 2.0 and mean CHA2DS2-VASc score was 3.7.

The primary outcome of the analysis was receipt of any OAC approved for stroke prevention during the study time frame. Overall, 44.9% of the cohort received an oral anticoagulant prescription, the group reported. The choice was warfarin for 90.3%, 7.7% for dabigatran (Pradaxa, Boehringer Ingelheim), and 2% for rivaroxaban (Xarelto, Bayer/Janssen Pharmaceuticals), at the time the only oral anticoagulants approved for AF in the US.

"These are registry data, and they may underestimate the true prevalence of oral anticoagulation, and unfortunately, they can't capture reasons for not prescribing oral anticoagulants or even patient preference. And the fact is that patients may have refused oral anticoagulants, so that could play into some of the numbers we saw," Hsu cautioned.

"That being said, I think the main message from our study is that even cardiologists need to heed this wake-up call—all of us in medicine have to work together to treat these patients with guideline-adherent medications."

Beyond Sins of Omission

In their critique, Piccini and Fonarow propose that the prevalence of oral anticoagulant prescribing might have been different had the authors followed patients over multiple visits, in which clinicians would have more opportunities to intervene. They also contend that known contraindications to oral anticoagulants in clinical practice are much higher than the 6% rate among patients included in the PINNACLE analysis.

On the other hand, Hsu told heartwire that his group carried out a sensitivity analysis to reclassify patients prescribed an oral anticoagulant within a year of the index visit, which showed that only 2.1% of patients not prescribed an oral anticoagulant at the baseline visit were prescribed one during the follow-up.

To move beyond simply pointing out physicians' sins of omission, Piccini and Fonarow propose a number of strategies to improve quality of care that include better patient education and shared decision making on use of oral anticoagulants. They also feel that organized quality-improvement efforts are "vital" to improving patient care, pointing to the Get With the Guidelines program that has posted anticoagulation rates for the same patient population at over 95%.

"There is overwhelming evidence for the net clinical benefit of oral anticoagulation in patients with moderate to high risk of stroke," Piccini and Fonarow conclude. "The challenge going forward will be to ensure that progress is universal and consistent."

Hsu reports receiving honoraria from Janssen Pharmaceuticals, Medtronic, and St Jude Medical as well as consulting fees from Celladon; disclosures for the coauthors are listed in the article. Piccini reports receiving grants for clinical research from ARCA Biopharma, Boston Scientific, Johnson & Johnson, Gilead, St Jude Medical, and ResMed and serving as a consultant to Bristol-Myers Squibb, GlaxoSmithKline, Janssen Pharmaceuticals, Medtronic, and Spectranetics. Fonarow reports serving as a consultant to Janssen Pharmaceuticals and Medtronic.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.