12-05-2025
Atrial Fibrillation: Should We Screen All to Reduce Stroke?
Is it time for universal screening for atrial fibrillation (AF), the most commonly treated type of arrhythmia that sets people up for strokes?
The question is important. While estimates of prevalence vary, a recent study found AF affects about 4% of the adult population or about 10 million in the United States. More than 795,000 people in the United States have a stroke each year, and AF is blamed for 1 in 7.
For now, however, US organizations that issue guidelines and many leading cardiologists agree: It's not yet warranted and may result in anticoagulation overtreatment, along with what they call the 'nontrivial' risk for bleeding from that treatment.
However, it's definitely a stay tuned situation, as researchers continue to investigate whether widespread screening can reduce the number of strokes in the broad population, others look at the role of 'smart' technology, and still others focus on subsets of the population that might benefit most from routine screening.
One widely anticipated study is the Heartline Study, a collaboration between Johnson & Johnson and Apple, with researchers analyzing the impact of an app-based heart health program done with the Apple watch on the early detection of irregular heart rhythms consistent with AF and how detection might reduce stroke risk. The trial has concluded, with results expected soon.
Current Guidelines
Meanwhile, two leading US organizations that issued recent guidelines do not favor universal screening for AF.
In 2022, the United States Preventive Services Task Force (USPSTF) guideline concluded that for asymptomatic adults aged 50 years or older, 'the current evidence is insufficient to assess the balance of benefits and harms of screening for atrial fibrillation.' The guideline updated the 2018 guideline, which assessed the evidence for detecting AF using ECG. The updated guideline also looked at other screening tests, still concluding the evidence was inadequate. Besides ECG use, AF may be detected using ambulatory blood pressure monitors, pulse oximeters or wearables, as well as pulse palpitation and heart auscultation.
In joint guidelines released in November 2023, the American Heart Association and American College of Cardiology concluded that for risk stratification models and screening programs to be useful, 'they would need to improve outcomes and be cost-effective,' noting that evidence is not established to prove those at a high risk for AF by a validated risk score benefit from screening and intervention to improve stroke rates, embolism rates, and survival.
Cardiologist: Currently Little Interest in Universal Screening
'To be honest with you, I don't think many in cardiology are interested in doing universal screening,' said Peter Zimetbaum, MD, associate chief and clinical director of Cardiology at Beth Israel Deaconess Medical Center and Smith professor of medicine at Harvard Medical School, Boston. After the USPSTF guidelines were issued in 2018, Annals of Internal Medicine published an invited point-counterpoint, with Zimetbaum presenting the viewpoint against routine screening.
Peter Zimetbaum, MD
He wrote: 'Atrial fibrillation is often asymptomatic and paroxysmal, and studies of episodic vs continuous monitoring have demonstrated that the more thoroughly one looks, the more AF will be found.'
The potential downside, he noted, is the unintended consequence of initiating lifelong anticoagulation treatment in patients who may not need it, including the potential risk for bleeding and negative impact on quality of life, which 'should not be minimized,' he said.
He does recommend screening in some, such as patients with a history of embolic stroke of uncertain source.
Taking the pro side in favor of screening, Steven Lubitz, MD, then at Massachusetts General Hospital, Boston, reasoned that AF may be asymptomatic and that subclinical AF is a known risk factor for stroke. He noted the various methods that can be used, including pulse monitoring and electrocardiology. Physicians are already screening for AF with pulse palpation and cardiac auscultation, Lubitz pointed out. The question is whether adding ECG is more effective than the standard of care.
Keeping an Open Mind
The question of routine screening is understandably an area of research interest, Zimetbaum said, as a significant percentage of patients present for the first time with AF when they have had a stroke, and ongoing advances in technology have made it easier to identify AF. The widespread adoption of wearable technologies such as smartwatches is also picking up AF in patients, he said.
Even so, he said, 'the reason why the organizations have come out not in favor of widespread screening is there is not enough evidence to demonstrate we can reduce strokes by identifying AF in the broadscale population.'
Many patients will come in to see him, Zimetbaum said, after they have AF picked up on their pacemaker, wanting to talk about the merits of anticoagulation treatment.
'I also get a lot of patients referred to me because they have a wearable of some sort that has alerted them that they have atrial fibrillation.' Of the wearables, he said 'they are reasonably accurate but not very accurate.'
Since 2019, when he wrote the counterpoint, 'my opinion has not changed.'
However, he is keeping an open mind. He said he expects wearables to improve and sees improving the accurate identification of AF as a goal worthy of more study.
Research Focus: Episode Duration, Risk Factors
Since the 2022 guidelines were issued, 'we do not have explosive new data to conclude this debate,' said Rod Passman, MD, MSCE, professor of medicine and preventive medicine at Northwestern University Feinberg School of Medicine in Chicago and director of the university's Center for Arrhythmia Research.
Rod Passman, MD, MSCE
However, 'the ARTESIA trial published in 2024 found a reduction in stroke risk when treating patients with anticoagulation who had short episodes of AF detected on their pacemaker or ICD [implantable cardioverter-defibrillators] who also had other stroke risk factors.'
But whether the same can be said for those with AF detected by other screening methods is not yet known, Passman said.
'There is no consensus on how much AF is too much,' Passman told Medscape Medical News . 'Most would agree that one or more episodes over 24 hours may benefit from anticoagulation if multiple other stroke risk factors are present; there is less consensus of opinion on episodes shorter than that.'
In a previous study, Passman and his colleagues found that a combination of AF duration and underlying risk factors increases stroke risk. 'AF episodes in someone with no or one risk factor may not increase stroke risk, but the more risk factors you have, the shorter the AF episodes associated with stroke.'
In his view, 'When we discuss screening, therefore, it is important to recognize that we should be screening those with an elevated risk of having the disease plus other risk factors that would dictate treatment should the disease be present.'
The Promise of Wearables
'Patients come to me every week because their watch told them they have AF,' Passman said. 'So using these technologies as a screening tool makes intuitive sense but has not yet been sufficiently proven to reduce hard endpoints such as stroke, in my opinion.'
Zachary Goldberger, MD, MS, a cardiologist and professor of medicine at the University of Wisconsin-Madison School of Medicine and Public Health, told Medscape Medical News : 'I think photoplethysmography can be a very powerful screening tool, but there are clear challenges. One is the amount of data we are going to receive, and already are receiving, and how much of that is interpretable and actionable.'
His hope: 'We really need to find a better means of identifying who we should target these wearables toward.' He added: 'It can't be ignored that this technology is not always affordable.'
