Remote screening yielded new cases of atrial fibrillation (Afib or AF) in the general population that otherwise would have gone undetected and untreated, according to the AMALFI trial in the U.K.
Afib was detected in 4.2% of older individuals -- selected for the study because they were at moderate to high risk of stroke but had no prior history of Afib or atrial flutter -- who underwent a 14-day course of continuous ambulatory ECG monitoring using the Zio XT wearable chest patch that they got through the mail.
Fast forward to 2.5 years later, when 6.8% of individuals randomized to mail-in screening officially had a primary care record of Afib -- significantly more than the 5.4% of controls who had received usual care without patch monitoring (ratio of proportions 1.26, 95% CI 1.02-1.57), Rohan Wijesurendra, DPhil, of the University of Oxford in England, reported here at the European Society of Cardiology (ESC) annual meeting.
By then, exposure to oral anticoagulation was slightly more in the intervention group than in the control group (1.63 vs 1.14 months, P<0.001), while stroke rates were statistically no different (2.7% vs 2.5%, RR 1.08, 95% CI 0.76-1.53).
"AMALFI has shown that it is possible to undertake screening for AF efficiently using a scalable approach that causes minimal disruption to healthcare staff and participants, and this design could inform a future national screening program," Wijesurendra said during a press conference.
The study manuscript was simultaneously published in JAMA.
Importantly, whether routine screening reduces stroke in a cost-efficient manner is still an unanswered question. Longer-term follow-up and health economic analyses are pending from the trial, according to Louise Bowman, MD, also from Oxford, who gave the main presentation of AMALFI at ESC.
Afib is an established risk factor in stroke. Nevertheless, mass screening for Afib is generally not accepted in clinical practice due to a paucity of evidence that potential benefits would outweigh any harms -- even if the point of screening would be to identify candidates for early intervention with anticoagulation to prevent stroke and other thromboembolic events.
Bowman said a key issue is that huge studies of screening would be needed to detect a real difference in stroke. She cautioned that even though the plan is to follow AMALFI participants out to 5 years, a difference in stroke would still not be expected given the sample of around 5,000.
Even so, session discussant Isabelle Van Gelder, MD, PhD, of University Medical Centre Groningen in the Netherlands, called AMALFI a "relevant, timely, and innovative" trial that fills in some important gaps in knowledge. She highlighted the simplicity and feasibility of the mail-in patch approach, stressing how it reached elderly, higher-risk people.
During the press conference, Wijesurendra acknowledged that prolonged screening devices like the Zio often turn up asymptomatic Afib episodes of unknown clinical significance. In AMALFI, over half the people with patch-detected Afib showed an Afib burden <10%, reflecting very little time that they were actually in Afib.
In clinical guidance, the clinical risk score rules and there's no distinguishing between high- and low-burden Afib. A high-risk patient is generally supposed to receive anticoagulation, which has bleeding as a major side effect in some individuals. "There is increasing awareness that low-burden AF does have a lower stroke risk," Wijesurendra said, but "what is the threshold where the benefit of anticoagulation exceeds the risk?"
Also playing against a population-wide continuous monitoring project is the fact that consumer wearables with ECG functions (e.g., Apple Watch) are already commonplace in the general public.
To what extent those outside devices affected the relative success of the mail-in Zio XTs in AMALFI is unknown. In the study, the mail-in patch screening boosted Afib detection rates to a smaller extent than expected because of the large number of Afib diagnoses not related to the patch, Wijesurendra suggested.
He acknowledged that his group lacked data on the nonpatch Afib diagnoses, especially whether they came out of patients having symptoms and getting them checked out by a clinician, or because they were wearing a wearable device that detected some Afib on its own.
In defense of the Zio strategy, Van Gelder pointed out that among those with Afib detected, the alarms went off much earlier with the mail-in patches (median 103 vs 530 days).
Then there is the issue of how much it would cost for systematic screening in the real world.
"AMALFI was conducted within a national health system that is universally accessible and free at the point of care; as such, the findings on the medium-term efficacy of an AF screening program may not be transferable to other settings," the authors reported.
The AMALFI investigators recruited about 5,000 people out of the more than 22,000 initially invited to the study based on their medical records from 27 primary care practices. In particular, the authors sought people 65 years or older with a CHA2DS2VASc score of 3 or higher (men) or 4 or higher (women) with no previous Afib or atrial flutter.
Participants were randomized to use an ECG patch monitor received by mail or continue usual care (n=2,520 each).
Across groups, the mean age was 78 years and 47% were women. Median CHA2DS2VASc score was 4.
Those assigned to the Zio device were told to undergo continuous ECG monitoring over a 2-week period. Just under 85% of the ECG patch group wore and returned their study devices, according to the AMALFI group. One in three turned out to have persistent Afib.
General practitioners managed the ECG findings at their discretion as part of clinical care.
Disclosures
The trial received funding from the National Institute for Health and Care Research Oxford Biomedical Research Centre and the British Heart Foundation (BHF). In-kind support for devices and ECG analysis was provided by iRhythm Technologies.
Wijesurendra and Van Gelder had no disclosures.
Bowman reported receiving grants from Novartis, Novo Nordisk, and BHF outside the submitted work.
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