Native Americans may be four times more likely to be diagnosed with atrial fibrillation — an irregular heart rhythm that can lead to strokes — if they get rapid screening using a smartphone app at checkups with their primary care doctors, a new study suggests.
The study, published April 21, 2021, in the Journal of the American Heart Association focused on Native American patients with an average age of 61 who received care at the Absentee Shawnee Tribal Health System in Oklahoma and had never been diagnosed with atrial fibrillation. Researchers compared atrial fibrillation diagnosis rates for 1,019 patients who consented to screening and got checked with the smartphone app and for 1,267 patients who didn’t agree to screening and got tested only if they reported symptoms.
Of patients who underwent screening with the smartphone app, 1.5 percent got diagnosed with atrial fibrillation, while only 0.3 percent of patients undergoing the usual care without screening got diagnosed, according to the research. This fourfold difference in diagnosis rates suggests that many cases of silent atrial fibrillation are going undetected among Native Americans, who appear about three times more likely to develop the condition than white people, says the lead study author, Stavros Stavrakis, MD, PhD, the director of cardiovascular research at the University of Oklahoma Health Sciences Center in Oklahoma City.
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“Using a mobile app to diagnose atrial fibrillation is feasible in a clinical setting and it is especially important for Native American populations, who have historically endured health disparities,” Dr. Stavrakis says. “It could also be used to diagnose atrial fibrillation in remote or underserved areas.”
Screening may help reduce health disparities by identifying patients with atrial fibrillation at younger ages, when they have the highest risk of severe stroke, says the senior study author, Ben Freedman, MBBS, PhD, of the Heart Research Institute Australia and Charles Perkins Centre at the University of Sydney. Almost half of the patients diagnosed after screening in the study were under 65 years old, an age when they’re at higher risk of strokes associated with atrial fibrillation, Dr. Freedman says.
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“This is preventable by oral anticoagulants, and that is what the people in this study received in the tribal clinics,” Freedman says.
All but one of the patients diagnosed with atrial fibrillation through screening in the study started treatment with medicines known as direct oral anticoagulants, anti-clotting drugs that can help prevent strokes. This family of medicines includes Eliquis (apixaban), Xarelto (rivaroxaban), Pradaxa (dabigatran), and Savaysa (edoxaban).
The study didn’t follow patients over time to see whether people diagnosed with atrial fibrillation through screening ultimately had fewer strokes than patients who didn’t get screened. Screening also wasn’t random — it was only provided to patients who consented — and it’s possible that people who agreed to undergo the test were different from patients who didn't in ways that might influence their risk of atrial fibrillation or strokes.
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Study Adds to Research Showing Heart Health Disparities in Native Americans
This isn’t the first study to highlight disparities in atrial fibrillation and stroke risk among Native Americans and other Indigenous populations.
A study published in Circulation in October 2019 followed more than 16 million U.S. patients for around four years and found Native Americans had a significantly higher risk of developing atrial fibrillation than all of the other racial and ethnic groups in the study. On average, 7.5 new cases were diagnosed each year for every 1,000 Native Americans, compared with 6.9 new cases a year among the other racial and ethnic groups.
An older study published in Circulation found Native Americans had a significantly higher risk of stroke than white or Black people in the United States — and that first strokes are much more likely to be fatal among Native Americans.
Indigenous populations elsewhere may also have an increased risk of atrial fibrillation. A study published in 2019 in Heart and Lung Circulation, for example, found aboriginal Australians were 1.4 times more likely to have atrial fibrillation than were nonaboriginal people. Another study, published in October 2017 in the International Medicine Journal, found that Māori and Indigenous New Zealanders were more likely to be diagnosed with atrial fibrillation than non-Indigenous people, and also more apt to have a high risk of stroke before age 65.
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Conflicting Screening Guidelines Partly Responsible for Disparities
Native Americans and other Indigenous populations who have a higher risk of atrial fibrillation at younger ages may fall through the cracks in part because of screening guidelines aren’t designed to catch these cases, Freedman says.
The U.S. Preventive Services Task Force, a government-backed panel of independent physicians, concluded in 2018 that there wasn’t enough evidence to recommend routine screening for atrial fibrillation with ECG, according to guidelines published by the Journal of the American Medical Association. Other influential medical groups, including the American Heart Association, the American Stroke Association, and the European Society of Cardiology, recommend screening for people 65 and older.
Much of the evidence behind these guidelines, however, doesn’t account for the elevated atrial fibrillation risk among Indigenous populations, says Katrina Poppe, PhD, a cardiovascular disease researcher with the faculty of medical and health sciences at the University of Auckland in New Zealand.
“What we’re seeing among Indigenous populations is that atrial fibrillation tends to start at younger ages than what we expect from the body of evidence we have, which is from white/European populations,” says Dr. Poppe, who wasn’t involved in the new study of Native Americans.
Screening needs to be more widely available for Indigenous people, and it should also start at younger ages, Poppe says.
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Why Screening for Afib Matters
One of the reasons atrial fibrillation can be so dangerous is that many people don’t notice any symptoms until the condition leads to a stroke.
Atrial fibrillation may be the cause of up to one-third of ischemic strokes, which occur when a clot blocks an artery carrying blood to the brain, according to a paper published in November 2019 in Circulation. This paper also notes that up to one in four patients who have an ischemic stroke or mini-stroke discover they have atrial fibrillation for the first time after these events.
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Many people may have silent atrial fibrillation that doesn’t become obvious until after a stroke, Poppe says. Many patients may also have symptoms like a racing heart or unexplained dizziness or shortness of breath, but fail to get it checked out because they can’t easily access or afford a checkup, Poppe adds.
“So screening not only picks up the silent cases of atrial fibrillation, but cases of atrial fibrillation in people who have been silent,” Poppe says.
How Mobile Screening Can Help
Mobile devices are being used more and more to help detect atrial fibrillation in a wide variety of settings, including primary clinics and pharmacies, says Russell Quinn, PhD, a clinical associate professor and cardiac electrophysiologist at University of Calgary in Alberta.
“This can be a good first step for making the diagnosis,” says Dr. Quinn, who wasn’t involved in the new study.
“How practical and feasible this is depends on how good the device is at detecting or excluding atrial fibrillation, and the background level of atrial fibrillation in the population screened,” Quinn adds.
For Native Americans and other Indigenous populations at high risk for atrial fibrillation, the benefits of mobile screening may outweigh the risk that it’s a false alarm, Quinn says. For other people who are younger or who don’t have other risk factors for atrial fibrillation, the potential for a “false positive” result from mobile screening may outweigh the benefits of screening asymptomatic individuals.
“If it is a very low risk population for atrial fibrillation, then screening will pick up many more false positives than true positives, which can lead to an unnecessary cascade of further testing and potential worry for the person who was screened,” Quinn adds. “So, targeting screening to higher-risk populations makes sense.”
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