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Compared with regular checks in primary care, continuous ECG monitoring revealed more asymptomatic older people with hypertension as having atrial fibrillation (Afib), the showed.

The Zio XT wearable ECG patch yielded an Afib detection rate of 5.3% by 6 months, compared with 0.5% achieved through standard care (RR 11.2, 95% CI 2.7-47.1), according to researchers led by David Gladstone, MD, PhD, of Sunnybrook Research Institute at the University of Toronto.

Within 6 months, 4.1% of people screened with the patch were prescribed oral anticoagulants versus 0.9% of controls receiving just routine follow-up plus a pulse check and heart auscultation (RR 4.4, 95% CI 1.5-12.8), according to the SCREEN-AF manuscript . The trial also tested intermittent oscillometric screening, which was far less effective for detecting Afib reliably.

"Most Afib cases were paroxysmal, with episodes lasting many hours. Patient adherence to [continuous ECG] was high, three-quarters of Afib cases were detected within the first 2 weeks of ECG monitoring, and 90% of cases would have been missed using a 24-hour Holter monitor," Gladstone's group reported.

Routine ECG screening for Afib is controversial and has not been backed by the U.S. Preventive Services Task Force on account of insufficient evidence.

In , continuous monitoring with the Zio patch improved Afib diagnosis and clinical outcomes over routine care. On the other hand, point-of-care rhythm assessment was a flop for most patients in the recent VITAL-AF trial.

"If the efficacy of [oral anticoagulation] for patients with low-burden, device-detected Afib is similar to that of clinically detected Afib, then future Afib screening programs could have major public health benefits for improving stroke prevention at a population level," Gladstone's team suggested.

That's an important "if," an suggested.

Two SCREEN-AF participants suffered ischemic strokes and one had a transient ischemic attack; all were in the ECG screening group, noted Roopinder Sandhu, MD, MPH, and Christine Albert, MD, MPH, both of Cedars-Sinai Hospital in Los Angeles.

This is "a reminder that Afib screening will not prevent all strokes in an older population, many of which may be due to causes unrelated to Afib," they wrote.

"The needle will only move forward once the results from studies evaluating clinical end points and cost-effectiveness are completed and more data are available regarding potential harms of screening. Ultimately, implementation will require a detailed assessment of health care systems' capacity to integrate Afib screening into routine care," Sandhu and Albert wrote.

Gladstone and colleagues similarly cautioned against "premature or inappropriate uptake of screening" in the meantime.

SCREEN-AF participants were 856 older community-dwelling individuals with hypertension and no known Afib who were judged to be at moderate or high risk for stroke. Mean age was 80.0 years, and 56.9% of participants were women.

The trial was conducted in Canada and Germany at 48 primary care practices in 2015-2019.

People randomized to the screening intervention underwent 2-week continuous ECG patch monitoring at baseline and at 3 months on top of standard care, plus automated home blood pressure (BP) machines with oscillometric Afib screening capability for use twice daily during the monitoring periods.

The Zio XT adhesive patch was worn on the chest for a median 27.4 out of 28 days. Adverse skin reactions leading to premature discontinuation of ECG monitoring occurred in 1.2% of study participants.

Among people who had Afib detected by the device, median total time spent in Afib was 6.3 hours, and median duration of the longest Afib episode was 5.7 hours. Anticoagulation was initiated in 75% of cases.

Results were less promising for intermittent oscillometric screening. A deluge of false positives and missed Afib episodes gave this form of screening a sensitivity of 35.0%, specificity of 81.0%, positive predictive value of 8.9%, and negative predictive value of 95.9%.

Gladstone's group acknowledged that the trial was underpowered to detect differences in clinical outcomes.

There were also numerically more withdrawals in the screening arm of the study (35 vs eight among controls); it is possible that the high rate of false positives from the BP monitors may have contributed to nonadherence to the screening protocol, Sandhu and Albert said.

Indeed, patient anxiety could be one of screening's potential harms, Gladstone's group acknowledged.

They said the main concern, however, would be of low-risk patients for whom anticoagulation may be unwarranted, which increases bleeding risk without benefit.

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