A new study has found that wearable technology may be catching up to, or in some ways surpassing, standard care for cardiac event detection.

The EQUAL trial, which was recently published in the Journal of the American College of Cardiology, showed smartwatches equipped with photoplethysmography (PPG) and ECG proved better at detecting episodes of new-onset atrial fibrillation.

“One of the most striking findings was the approximately four-fold increase in atrial fibrillation detection compared with standard care. Importantly, a large proportion of these newly detected episodes consisted of paroxysmal and asymptomatic atrial fibrillation, which are well known to be challenging to identify with conventional, short-duration rhythm monitoring,” Nicole J. van Steijn, MD, first author, and Michiel M. Winter, MD, PhD, principal investigator of the EQUAL trial, told Medscape Medical News. 

For more than a decade, people have been using smartphones and smartwatches to track health data. In a narrative review published in the Journal of Medical Internet Research, researchers examined cardiovascular mHealth apps and wearables — primarily from Germany, Austria, and Switzerland — and evaluated their clinical value for patients and clinicians. They concluded that wearables are more likely than most smartphone health apps to be backed by solid research and formal medical validation, making them more credible for clinical use.

However, no randomized controlled trial has assessed smartwatch-based atrial fibrillation screening in a high-risk secondary-care population using a device that combines both PPG and ECG capabilities until now, van Steijn, Winter, and colleagues wrote in the recent JACC study. 

Earlier Detection 

The EQUAL trial was a prospective, multicenter randomized controlled study conducted at two secondary care cardiology centers in the Netherlands. Researchers looked at whether smartwatch-based monitoring integrating both PPG and ECG could improve detection of new-onset atrial fibrillation compared with standard care.

The trial enrolled 437 adults aged 65 years or older with elevated stroke risk, defined by CHA₂DS₂-VASc scores of at least 2 for men and 3 for women, and no history of atrial fibrillation. Participants were randomized 1:1 to either 180 days of smartwatch-based monitoring with an Apple Watch or usual care, which included clinician-directed ECG testing, inpatient telemetry, or handheld rhythm monitoring, as clinically indicated. 

Participants in the intervention group were instructed to wear the smartwatch for at least 12 hours daily and to record a 30-second single-lead ECG when symptoms occurred or when the device detected an irregular pulse pattern suggestive of atrial fibrillation. All smartwatch ECGs were automatically transmitted to a centralized telemonitoring platform and reviewed within 24 hours by a trained eHealth team, with cardiologist oversight.

The primary endpoint was new-onset atrial fibrillation, defined as an episode lasting at least 30 seconds confirmed on single-lead or standard ECG.

Over the 6-month follow-up, new-onset atrial fibrillation was detected in 9.6% of patients in the smartwatch group compared with 2.3% in the control group, with an absolute risk difference of 7.3 percentage points (P = .001). 

Results also showed nearly 60% of atrial fibrillation cases in the intervention group occurred without symptoms, whereas all atrial fibrillation diagnoses in the control group were driven by symptoms. These findings underscore a key limitation of standard care: symptom-triggered monitoring often misses intermittent, silent arrhythmias.

Notably, 20 of the 37 patients in the intervention group with at least one atrial fibrillation reading were clinically diagnosed with atrial fibrillation that was confirmed by the eHealth adjudication team and the treating physician based on ECG review. These data yielded a positive predictive value of 54%.

‘A First Step’ 

In older adults at elevated risk for stroke, 6 months of smartwatch-based monitoring significantly increased detection of new-onset atrial fibrillation compared with standard care. The findings support wearable-enabled remote monitoring as a viable strategy for identifying otherwise undiagnosed, often asymptomatic atrial fibrillation — provided it is paired with clinical adjudication and integrated care pathways, according to the researchers. 

Peter R. Kowey, MD, author of Failure to Treat, also urges clinical consultation when using any smartwatch device for screening and detection. 

“Since the publication of the Apple Heart study in 2019, it has become clear that using a consumer-purchased device to detect atrial fibrillation is feasible and reasonable. The Apple Watch works, so diagnosing atrial fibrillation more frequently by using it is hardly surprising,” Kowey, one of the Apple Heart investigators, told Medscape Medical News.

Kowey, who was not involved with the recent study, highlighted some concerns, though.

“An important finding was a false positive rate of atrial fibrillation detection of 46%, underscoring the need to validate the findings of consumer devices before making any decisions about clinical significance or management. The decisions about anticoagulation or atrial fibrillation suppression with ablation or drugs are complex and must consider a variety of clinical factors,” said Kowey, who is also William Wikoff Smith chair in cardiovascular research at the Lankenau Institute for Medical Research and emeritus chief of cardiology at the Heart Center of Lankenau in Pennsylvania.

“Atrial fibrillation detection using an Apple Watch should be considered a first step. Consultation with a knowledgeable physician will be essential to ensure the best care of these vulnerable patients,” he said.

Van Steijn received a travel grant from Apple. Apple also loaned their Apple Watches for the study. The study was funded by the Bob Vlake Foundation. 

Lois Anzelowitz Levine is a medical writer who lives in Dallas.