Substantial Minority of Low-Risk A-fib Patients Still Given Anticoagulants

As many as 1 in 4 A-fib patients at low thromboembolic risk are prescribed oral anticoagulants, according a research letter online April 13, 2015, ahead of print in JAMA Internal Medicine.

For the registry study, Gregory M. Marcus, MD, of University of California, San Francisco Medical Center (San Francisco, CA), and colleagues analyzed data on 10,995 “healthy” A-fib patients younger than 60 years old who had no structural heart disease and were at low risk for thromboembolism. All patients—treated at 76 cardiology practices in 33 states—were enrolled in the National Cardiovascular Data Registry’s PINNACLE Registry between 2008 and 2012.

All patients had a CHADS₂ risk score of 0 and 6,370 a CHA₂DS₂-VASc score of 0. Within those groups, 23.3% and 26.6% patients, respectively, were prescribed oral anticoagulants.

On multivariate analysis, independent predictors of anticoagulant prescription in the CHADS₂ cohort included older age, male sex, higher BMI, and having Medicare compared with private insurance (table 1).

Additionally, treatment in the South, West, or Northwest was associated with a lower likelihood of being prescribed oral anticoagulants compared treatment in the Northeast.

Among patients with a CHA₂DS₂-VASc score of 0, an additional predictor of oral anticoagulant prescription was having no insurance compared with private insurance (adjusted RR 1.19; 95% CI 1.03-1.37).

Under-, Overtreatment Both Concerns

In a telephone interview with TCTMD, study coauthor Jonathan C. Hsu, MD, MAS, of the University of California, San Diego Health System (La Jolla, CA), said oral anticoagulants are generally under prescribed to A-fib patients at high risk of stroke.

“This study shows that we are not doing all that well on both ends of the spectrum,” he observed. “We are undertreating patients who need these drugs and overtreating patients for whom the risks outweigh the benefits.”

But Jonathan P. Piccini, MD, MHSc, of Duke University Hospital and Duke Veterans Affairs Medical Center (Durham, NC), said many A-fib patients who were once considered as having a very low risk for stroke are now recognized as having an intermediate risk. Even the newer CHA₂DS₂-VASc model might be missing important contributors to stroke risk, he explained.

“We are learning about new risk factors for stroke all the time,” Dr. Piccini said. “[Treatment] guidelines in 2006 were very different from the guidelines we follow today, and I expect guidelines in 2018 or 2020 will be different as well.”

Scores May Not ‘Fully Describe’ Risk

Allen Jeremias, MD, MSc, of Stony Brook School of Medicine (Stony Brook, NY), said the lack of information in the PINNACLE Registry on A-fib-related procedures during the observation period is a study limitation that could at least partially explain the results. Oral anticoagulants are prescribed before and after electrical cardioversion or catheter ablation, he noted.

“It is possible that patients in the Northeast, where the highest use of anticoagulants occurred, are having more procedures and that this is reflected in the findings,” Dr. Jeremias told TCTMD in a telephone interview. “But, despite this caveat, it does appear that a significant proportion of patients are being treated when it is not indicated and not medically necessary.”

Dr. Piccini also cited A-fib procedures as a potential confounder and noted that it is likely some are receiving anticoagulants for unknown reasons.

“I suspect that, of those, 1 in 4 patients maybe really shouldn’t be on an oral anticoagulant, but I think there are also many for whom the risk scores don’t fully describe their risk,” he said, adding that, like most good research, the study raises more questions than it answers.

Source:
Hsu JC, Chan PS, Tang F, et al. Oral anticoagulant prescription in patients with atrial fibrillation and a low risk of thromboembolism: insights from the NCDR PINNACLE Registry [research letter]. JAMA Intern Med. 2015; Epub ahead of print.

Disclosure:

• Dr. Marcus reports receiving research support from Medtronic and SentreHeart.

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