New Smart Device Shows Highly Accurate AF Detection: mAFA II

April 12, 2022

Screening for heart rhythm disorders with a smartphone app and a wearable device had a high rate of correctly detecting atrial fibrillation (AF) in a large new study.

The mAFA II study, conducted in a mass low-risk population in China, showed that more than 93% of possible AF episodes detected by the smartphone app were confirmed to be AF on further monitoring.

The study also used the app to screen for obstructive sleep apnea and found that sleep apnea was the most common risk factor associated with increased AF susceptibility, and those identified as having the most severe sleep apnea were 1.5 times more likely to have AF than those who did not have this condition.

This suggests that tools suitable for detecting both AF and sleep apnea can work synergistically to further enhance health monitoring, said lead author, Yutao Guo, MD, professor of internal medicine at Chinese PLA General Hospital in Beijing, China.

Guo presented the mAFA II study at the American College of Cardiology (ACC) 2022 Scientific Session held last weekend in Washington, DC, and online.

The trial, which involved more than 2.8 million participants, is the largest study to date to demonstrate how wearable consumer technologies can be used to screen for heart problems during everyday activities, Guo noted.

"Consumer-led screening with these technologies could increase early diagnosis of AF and facilitate an integrated approach to fully implement clustered risk management to reduce AF burden and its related complications," she concluded.

Discussant of the study at the ACC "Featured Science" session at which it was presented, Jodie Hurwitz, MD, Director of the Electrophysiology Lab at Medical City Hospital in Dallas, Texas, called this, "a pretty impressive study. To get a 93.8% confirmation of AF with these devices is great."

But Hurwitz pointed out that the age of patients in the study was relatively young (average 37 years), and the group who really need to use such a device is much older than that.

"The take-home messages from this study are that AF wearable detection algorithms have the ability to detect true AF, and that they might also be able to detect risk factors (such as sleep apnea) that predispose to AF possibly even before AF is present," Hurwitz commented to | Medscape Cardiology.

Moderator of the session, Edward Fry, MD, cardiologist at Ascension St. Vincent Heart Center, Indianapolis, Indiana, and incoming president of the ACC, described the area of AF screening with smart devices as "fascinating, especially with the perspective of the scalability of these types of studies."

The mAFA II study tracked more than 2.8 million people who used a Huawei phone app together with Huawei and Honor smart devices incorporating photoplethysmography (PPG) technology, a light-based method to monitor blood flow and pulse. If an abnormal rhythm was detected, the wearer would be contacted by a clinician to set up an appointment for a clinical assessment.

Over the course of 4 years of the study, 12,244 (0.4%) of users received a notification of suspected AF. Among 5,227 people who chose to follow up with a clinician, AF was confirmed in 93.8% of patients using standard AF diagnostic tools including clinical evaluation, an electrocardiogram and 24-hour Holter monitoring.

In this study, a subset of the individuals screened for AF were also screened for signs of sleep apnea using the same PPG technology to detect physiological changes in parameters including oxygenation and respiratory rates. The app is also able to determine whether the individual is awake or asleep. Guo noted that the PPG algorithm for obstructive sleep apnea risk has been validated compared to polysomnography or home sleep apnea tests.

Using measurements of apnea (signalled by a reduced respiratory rate) and hypopnea (when oxygenation would decrease), the apnea­–hypopnea index (AHI) is calculated to determine the severity of the sleep apnea.

Of the 961,931 participants screened for sleep apnea, about 18,000 were notified they may have the condition.  

Obstructive sleep apnea was the most reported common risk factor associated with increased AF susceptibility, and those individuals with the highest risk sleep apnea (more than 80% monitoring measures with AHI ≥ 30 during sleep) resulted in a 1.5-fold increase in prevalent AF, Guo reported.

The mAFA II is the latest of several studies to show that AF can be detected with various smartphone apps and wearable devices. Previous studies have included the Fitbit Heart Study and the Apple Heart Study.

Hurwitz told | Medscape Cardiology that the electrophysiologist community is enthusiastic about this new smart device technology.

"I sent my sister one so she could determine if she develops AF: That's a pretty good endorsement," she commented, but added that there are still concerns about the rate of false-positive results.

Hurwitz said she suspected that there will probably be meaningful differences between the different apps and devices, but the algorithms are all proprietary and the use of photoplethysmography seems to make a big difference.

She noted that the detection of sleep apnea in the current study was a novel approach. "This is important, as sleep apnea is felt to contribute to AF and treating it is felt to decrease the frequency of AF. Perhaps if patients with sleep apnea were treated before they had documented AF, the AF burden could be reduced," she said.

She added that further studies were needed to fine tune the algorithms, and to try and identify other factors or heart rate variabilities that may predict future risk of AF.

The study was funded by the National Natural Science Foundation of China. Guo reports no disclosures.

American College of Cardiology (ACC) 2022 Scientific Session. Presented April 3, 2022. 


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