A-fib Screening With Smartphone-Based ECG Feasible, but Clinical Impact Unclear


Screening the general adult population for A-fib using a smartphone-based, wireless, single-lead ECG is feasible and can identify “a significant proportion” of people previously unknown to have the arrhythmia, a new study conducted in Hong Kong suggests.

Of people screened with the AliveCor device, 0.8% received a new diagnosis of A-fib, likely representing the nonparoxysmal form of the condition, Ngai-yin Chan, MBBS, and Chi-chung Choy, MD (Princess Margaret Hospital, Lai Chi Kok, Hong Kong), report in a study published online October 12, 2016, ahead of print in Heart.

The overall prevalence of atrial fibrillation detected using the device was 1.8%. Combining device-detected and self-reported cases brought that figure up to 8.5%, comparable to the prevalence seen in recent studies conducted in Western nations, according to the authors.

What remains unclear is what impact, if any, such a screening effort would have at a population level. “Whether a systematic population-based ECG screening for [A-fib], instead of an opportunistic approach as recommended by the current guidelines, leads to a reduction in the incidence of stroke in a community requires a well-designed randomized controlled study,” they write.

Although numerous questions remain, some type of A-fib screening appears to be warranted, Emma Svennberg, MD, and Johan Engdahl, MD, PhD (Karolinska Institute, Stockholm, Sweden), suggest in an accompanying editorial.

“Taking into account its present and future prevalence, the availability of several well-documented [oral anticoagulation] options, the prevalence of silent [A-fib] and the consequences for undiagnosed and untreated patients, and the availability of simple and cost-effective options for ECG recording, [A-fib] seems to fulfill all criteria for population screening endorsed by the World Health Organization,” they write.

Gaps in Knowledge About A-fib Screening

The potential for A-fib screening has been explored in several studies, but there are many unknowns surrounding how screening should be done, what populations should be targeted, and how patients diagnosed with silent A-fib should be managed, the editorialists note.

For the current study, Chan and Choy led a community screening program that recruited participants through a media campaign and advertisements. Ultimately, 13,122 adults were evaluated using the AliveCor device between May 2014 and April 2015. The ECGs were performed by trained, nonmedical volunteers.

“To the best of our knowledge, this is currently the largest study in mass screening for [A-fib] in the general population,” the authors say.

Only 0.4% of the ECGs were uninterpretable. Of the patients newly diagnosed with A-fib, about two-thirds (65.3%) were asymptomatic. Predictors of device-detected A-fib included older age, increased body weight, lower body mass index, heart failure, valvular heart disease, stroke, and a history of cardiothoracic surgery.

According to the editorialists, the authors of the current study “should be complimented for bringing new data into the important area of stroke prevention in patients with [A-fib].”

Searching for Things Other Than Pokémons

But Svennberg and Engdahl also raise some issues regarding the study.

Because there was a lack of detailed information about the advertisement campaign used to recruit participants, the effectiveness of the approach is not clear, they note, adding that using media campaigns in this way can introduce bias.

Pointing out that this study included all people 18 and older, they say that a higher age threshold would be preferred if the intention of a screening program is to get a high yield accompanied by a reduction in stroke risk among diagnosed adults.

And finally, there were no data on how many patients received oral anticoagulation as a result of screening, which “represents the most significant drawback of the study since [A-fib] detection per se does not give stroke prevention, unless combined with adequate . . . treatment,” the editorialists write.

Yet they threw their support behind population screening for A-fib. “In order to relieve both patients and society from the consequences of untreated [A-fib], we believe and hope that [such] screening in risk groups will be a part of the standard healthcare in many countries in the near future,” Svennberg and Engdahl write. “Besides, isn’t it encouraging that we can use our smartphones to search for other things than Pokémons?”

Sources
  • Chan N-Y, Choy C-C. Screening for atrial fibrillation in 13,122 Hong Kong citizens with smartphone electrocardiogram. Heart. 2016;Epub ahead of print.

  • Svennberg E, Engdahl J. Why should we screen for atrial fibrillation? Heart. 2016;Epub ahead of print.

Disclosures
  • Chan and Choy report no relevant conflicts of interest.
  • Svennberg reports receiving lecture fees from Merck Sharp & Dohme, Bristol-Myers Squibb-Pfizer, Boehringer Ingelheim, and Sanofi and a research grant from Boehringer Ingelheim.
  • Engdahl reports receiving consultancy fees from Sanofi and Pfizer, lecture fees from AstraZeneca, Boehringer Ingelheim, Medtronic, and Bristol-Myers Squibb, and travel expenses from Boehringer Ingelheim and Sanofi.

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