USPSTF Not Backing Afib Screening, Even With Wearables

While experts agreed with the U.S. Preventive Services Task Force’s (USPSTF) finalized recommendations that affirmed no recommendation for atrial fibrillation (Afib, AF) screening in middle-age and older adults without symptoms, they noted that there might be no stopping it anyway.

The “I” statement of insufficient evidence for such screening among adults 50 and older without a history of transient ischemic attack or stroke, published in JAMA, matched the draft recommendations released last May and a similar statement from 2018 that said there isn’t enough evidence that benefits outweigh potential harms.

The update extended that determination to cover not only in-office ECG but also wearables with ECG capabilities, like the Apple Watch, as well as smart devices using photoplethysmography, and even pulse oximeters or blood pressure cuffs that use algorithms to detect irregular heartbeats indicative of Afib.

There’s plenty of evidence now that more screening catches more Afib, especially when using continuous-monitoring devices, said the USPSTF members in their statement.

“We find this conclusion reasonable because most asymptomatic AF is intermittent, and it stands to reason that continuous monitoring will detect more AF than intermittent monitoring over short time periods,” commented John Mandrola, MD, of Baptist Health Louisville in Kentucky, and Andrew Foy, MD, of Pennsylvania State University College of Medicine in Hershey, in an editorial in JAMA Internal Medicine.

The problem was in finding evidence to support improved clinical outcomes in the face of known small to moderate risks of harm from increased risk of major bleeding when starting anticoagulation for screen-detected Afib.

The accompanying evidence review turned up no trials that have assessed benefits and harms of anticoagulation in asymptomatic screen-detected Afib. Two recent trials didn’t provide much help in that regard.

The STROKESTOP trial randomized all 75- to 76-year-old adults in two regions of Sweden to be invited to screening with twice-daily single-lead ECG for 14 days or standard care. It showed no greater rate of detected Afib or use of oral anticoagulation in the screening group after 7 years, “suggesting that, given time, standard care will discover most cases of AF,” Mandrola and Foy pointed out.

And while the primary endpoint was met, the absolute risk reduction in the composite of ischemic or hemorrhagic stroke, systemic embolism, bleeding requiring hospitalization, and all-cause death was just 0.23%. One additional event in the screening group would have rendered that finding nonsignificant, the editorialists pointed out. There was also no difference in ischemic stroke alone.

The LOOP trial, published in August after the USPSTF had already finished its review, randomized individuals 70 and older without known Afib to either an implantable loop recorder or standard care, with oral anticoagulation encouraged for any detected episodes longer than 6 minutes. In this case, Afib diagnoses and oral anticoagulation roughly tripled with the loop recorder over the median 64 months of follow-up. Yet, the 1.1% absolute risk reduction in the primary outcome of time to first stroke or systemic embolism was not statistically significant.

The European Society of Cardiology, using the same admittedly “scarce” evidence base, concluded in favor of Afib screening (class I for opportunistic screening in patients 65 and older, class IIa for systematic ECG screening in patients with high stroke risk or those 75 and older) in 2020 guidelines, citing the likely benefits of early detection and treatment in selected older adults as justification.

The American Heart Association also supports Afib screening as potentially useful for adults 65 and older in the primary care setting, using pulse assessment followed by ECG as indicated, the task force members noted.

However, Mandrola and Foy argued that “nonbeneficial interventions that add cost are not helpful for patients and create a net harm to society.”

Other concerns include “anxiety generated by abnormal findings, misinterpretation of the ECG results that could result in overdiagnosis and overtreatment, and the possibility of unnecessary downstream testing,” added Philip Greenland, MD, of Northwestern University Feinberg School of Medicine in Chicago, in an editorial in JAMA.

“Despite the caution appropriately emphasized by the USPSTF, screening will likely increasingly occur outside of physician encounters,” acknowledged Matthew Kalscheur, MD, and Zachary Goldberger, MD, both of the University of Wisconsin-Madison, in an editorial in JAMA Network Open.

When consumer-available devices land these patients in the office, there just isn’t enough evidence to guide management decisions in a way to ultimately improve outcomes, Mandrola and Foy wrote.

The way forward might be very large trials enrolling only higher-risk patients with longer-duration monitoring and longer-duration thresholds for identifying Afib, Greenland suggested.

Another possibility are clinical trials of structured, patient-specific behavior interventions for screen-detected Afib targeting modifiable risk factors, including obesity, hypertension, alcohol use, sleep apnea, smoking, and diabetes, Kalscheur and Goldberger added.

“The hope is that a future USPSTF report will eventually be able to either endorse — or advise clearly against — AF screening by ECG based on clear, objective evidence from well-conducted randomized trials,” Greenland concluded.