In this three part series, we’ll look first at current screening strategies and some of the limitations that create an opportunity for emerging tools. Then we’ll dive into some of the tools that will define the next generation of atrial fibrillation screening. This is Part 2.
Atrial fibrillation is an increasingly prevalent arrhythmia; it currently affects three to six million of Americans and that number is expected to rise. And unlike many other medical conditions, it is often silent until discovered either incidentally or after a serious complication like a stroke.
A number of trials have evaluated different screening strategies including opportunistic screening where patients are screening at a single time point, such as at a doctors visit or health fair. That strategy was looked at in the SAFE trial, which found that opportunistic screening with pulse palpation was as effective as EKG screening and increased detection over usual care. There were however important limitations that impact the generalizability of those strategies such as accuracy, cost, and resource-intensiveness.
Here, we’ll look at how emerging mobile health tools could change the equation when it comes to opportunistic screening.
The “Smartphone ECG” for opportunistic screening
There are a number of emerging and recently available options for opportunistic screening that make the environment very different to that encountered in SAFE nearly ten years ago.
One of the most prominent, a poster-child for mobile health, is the AliveCor device. When we first reviewed the device in early 2013, we highlighted that data on the utility of the device just wasn’t there yet. Since then, AliveCor answered with a study in Australia using their Heart Monitor in an opportunistic screening program targeting adults over sixty five based out of pharmacies7. In a similar, but much smaller, population to that of SAFE, they had a detection rate of 1.5% of new or recurrent atrial fibrillation. Since then, they have had their automated atrial fibrillation detection algorithm approved by the FDA.
In whole, the device plus a paired smartphone will run a few hundred dollars. Given the usability and portability of the device without the need for any trained staff, its not hard to imagine it becoming part of the commonly seen kiosks at pharmacies as well used in other community-based screening programs. And given high costs associated with a single atrial fibrillation related stroke, it seems likely that the cost-effectiveness will work out in its favor.
We should note also that the AliveCor Heart Monitor isn’t the only player in this area. ECG Check from Cardiac Designs is has received 510(k) clearance from the FDA and CE mark in Europe; you can buy it on Amazon.
Screening with nothing more than a camera
Another modality that has yet to become available is the use of smartphone cameras for the detection of atrial fibrillation. The effectiveness of detection was described by McManus et al in their paper in Heart Rhythm in 2013, in which they validated their detection algorithm in atrial fibrillation patients undergoing cardioversion8. Here, the camera and flash basically work like a pulse oximeter and use photoplethysmography to detect a pulse; using an algorithm that essentially looks for disordered beating, they achieved a sensitivity and specificity of approximately 97% for the detection of atrial fibrillation.
Subsequent publications from this group suggest that further refinement of the signal processing is being undertaken to help bring this technology to the point where it could be used clinically9,10. Once that is accomplished, screening for atrial fibrillation could become as simple to pulling out your phone. Effectiveness and safety would hinge on developing strategies that ensure appropriate self-screening; that could be as simple as a questionnaire on the opening app that applies something akin to the Heart Rhythm Society’s atrial fibrillation risk assessment toolc and specifically guides patients on whether they should screen.