A new statement from the US Preventive Services Task Force (USPSTF) concludes that the current evidence is insufficient to assess the benefit-harm balance of screening for atrial fibrillation (AF) in asymptomatic adults.
The guidance is similar to the 2018 task force statement on screening for atrial fibrillation with electrocardiography (ECG) in asymptomatic adults age 65 and older, but lowers the age of inclusion to adults age 50 and older.
“This 2021 evidence review included searching for evidence on additional screening methods such as automated blood pressure cuffs, pulse oximeters and consumer devices such as smartwatches and smartphone apps. However, even with this expanded scope, the USPSTF found no evidence to recommend or against screening for atrial fibrillation,” the task force notes.
The prevalence of atrial fibrillation increases with age from less than 0.2% in adults under 55 to about 10% in those over 85, the group said. Prevalence is higher in males than females, but it is uncertain whether it differs by race and ethnicity.
Although atrial fibrillation significantly increases the risk of stroke, the risk of stroke associated with subclinical atrial fibrillation, particularly for shorter durations of less than 24 hours or less exertion, as might be detected by some screening approaches, is “uncertain,” the task force adds.
The updated recommendations will be published online in JAMA on January 25, along with a separate evidence report and editorial.
The task force reviewed 26 studies involving 113,784 patients, including 12 new ones in the update.
Studies showed that systematic screening detected significantly more AF than no screening or pulse testing (absolute difference, 1.0% to 4.8% over up to 12 months). However, in two of the studies, only 10.7% and 44.5% of participants actually received the screening test, respectively.
The review included three randomized screening-versus-no-screening trials that reported health outcomes, but only one, STROKESTOP, was targeted at health outcomes. The risk for the primary composite endpoint of ischemic or hemorrhagic stroke, systemic embolism, bleeding leading to hospitalizations, and all-cause mortality was found to be significantly lower with twice-daily intermittent single-lead ECG monitoring for 14 days compared to no screening was. However, there were no significant differences in the individual endpoints of the composite endpoint.
“Additionally, and probably the most important thing to appreciate about the STROKESTOP study, is that it has several limitations,” Task Force member Gbenga Ogedegbe, MD, MPH, New York University, New York told theheart. org | Medscape Cardiology. The intervention was not masked and outcomes were not assessed centrally.
In addition, “Approximately 11% of the patients in the study had a history of transient ischemic attack (TIA), stroke, or embolism, and the population we are studying within the task force are people without symptoms or with a history of stroke or ischemic attack . ” he said. “That’s the fundamental difference here. So these limitations make it difficult to say that STROKESTOP actually has benefits.”
Notably missing from the review was the recently published LOOP study, which found no significant benefit in outcomes from continuous monitoring with an implantable loop recorder (ILR) over usual care in older adults.
Although it “provides some context for this issue,” it was not considered for inclusion because 25% of the population had a history of stroke, TIA, or embolism and “because this primary care screening approach may not be feasible,” Lead author of the Evidence Report Leila Kahwati, MD, MPH, of the RTI International Social and Health Organizational Research and Evaluation Program and the School of Medicine at the University of North Carolina at Chapel Hill, explained in an email.
Warfarin treatment (mean 1.5 years) was associated with a lower risk of ischemic stroke (relative risk 0.32) and all-cause mortality (relative risk 0.68), while direct oral anticoagulants were associated with a lower incidence of stroke were (adjusted odds ratio range 0.32 – 0.44). Patients had an increased risk of major bleeding on both warfarin (pooled relative risk 1.8) and direct-acting oral anticoagulants (odds ratio 1.38-2.21), but confidence intervals did not exclude a null effect.
The USPSTF found no studies reporting the benefits of anticoagulant therapy in screen-detected patients.
In an accompanying editorial, Philip Greenland, MD, notes that the task force’s conclusion deviates from the European Society of Cardiology’s 2020 AF guideline, which recommends opportunistic screening for atrial fibrillation by pulse palpation or ECG rhythm strips in patients 65 and older ( Class I recommendation) and advises physicians to consider systematic ECG screening to detect atrial fibrillation in those aged 75 or older or those at high risk of stroke (Class IIa).
To potentially clarify whether screening for atrial fibrillation in asymptomatic patients is warranted, “future studies need to consider including only higher-risk patients and identifying those with longer-lasting atrial fibrillation,” said Greenland, JAMA editor and professor of preventive medicine and Medicine at Northwestern University Feinberg School of Medicine, Chicago, Illinois.
“An important issue raised by the LOOP study is whether there is a threshold level of atrial fibrillation duration that is most strongly associated with stroke risk and therefore most likely to benefit from anticoagulation,” he writes. In fact, the LOOP authors themselves questioned whether the study’s short atrial fibrillation duration of 6 minutes might have resulted in many low-risk patients being diagnosed and treated.
“Additionally, studies need to recognize the need for longer monitoring periods (preferably continuous), and perhaps novel wearables will enable long-term monitoring with accurate ECG interpretation and long-term adherence,” Greenland said.
In a related editorial in JAMA Internal Medicine, John Mandrola, MD, Baptist Health Louisville, Kentucky, and Andrew Foy, MD, Pennsylvania State University College of Medicine, Hershey, note that continuous ILR monitoring in LOOP Study 3 -times more resulted in atrial fibrillation and resulted in 2.7-fold higher rates of oral anticoagulant use compared to standard of care. However, there was no statistically significant difference in stroke reduction, and the 20 percent relative reduction in thromboembolic complications in the screened group was offset by a 26 percent relative increase in major bleeding.
“Perhaps the most notable aspect of AF screening studies is that as screening tools improve, from a single 12-lead ECG to 14-day recordings and then the ILR always on, more AF is detected and more [oral anticoagulant] is used, but there is little detectable improvement in outcomes,” write Mandrola and Foy.
The editors also note the potential of rhythm monitoring to lead to misdiagnosis and downstream care cascades. “If you assume a 2% prevalence of atrial fibrillation, even a device with a specificity of 98% will misdiagnose approximately 2000 people per million people screened.”
Mandrola told theheart.org | Medscape Cardiology believes that the “greatest value” of these atrial fibrillation screening reports and critiques is that they serve to reflect on the limitations of disease screening. As James Maxwell Glover Wilson and Gunner Jungner wrote in their 1968 textbook Principles and Practice of Screening for Disease: “In theory, screening is an admirable method of controlling disease…[but] in practice there are catches.”
“It would be good for the public to understand these hooks … because they also apply to cancer, coronary calcium testing and vascular screening,” Mandrola said.
When asked if it’s possible to put the genie back in the bottle now that every other patient in the clinic might have an EKG on their wrist, Ogedegbe said: “If a patient doesn’t have a history of stroke or TIA and 50 years or older, really, monitoring with these devices for Afib there is no evidence for or against. Ultimately, the clinician must use clinical judgment when speaking to these patients.
A related editorial in JAMA Cardiology suggests that, to be effective, the movement toward consumer-based screening must first show that such an approach improves outcomes and address the paradox that those at highest risk for Atrial fibrillation and atrial fibrillation-related stroke may be the least likely to possess these technologies unless supported by healthcare systems.
“Additionally, appropriate treatment pathways need to be established to confirm the diagnosis and, if necessary, initiate appropriate treatment in individuals with positive findings,” Rod Passman, MD, Northwestern University, and Ben Freedman, MBBS, PhD, University of Sydney, Australia, say. “It will also be crucial to ensure that device costs and differing levels of technological expertise do not create barriers to making screening accessible to all risk groups.”
Finally, in a related editorial in JAMA Network Open, Matthew Kalscheur, MD, and Zachary D. Goldberger, MD, both of the University of Wisconsin-Madison, say the potential benefits of early AF detection should go beyond stroke prevention.
“Patients diagnosed with atrial fibrillation would likely benefit from targeted treatment of modifiable risk factors that contribute to atrial fibrillation, including obesity, hypertension, alcohol use, sleep apnea, smoking and diabetes,” they write.
JAMA. Published online January 25, 2022. Statement of Recommendation, Evidence Report, Editorial
The USPSTF is an independent, voluntary body. The US Congress directs the Agency for Healthcare Research and Quality to support the work of the USPSTF. All members of the USPSTF receive travel expenses and a fee for attending USPSTF meetings. The original article lists relevant financial relationships of task force members. Ogedegbe included a study on the subject in the Evidence-based Practice Center report. Kahwati did not report any relevant financial conflicts of interest. . Greenland reported receiving research grants from the National Institutes of Health and the American Heart Association. Mandrola is a regular contributor to theheart.org | Medscape Cardiology. Foy, Kalscheur and Goldberger disclosed no relevant financial relationships.
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