In separate press releases, Apple and the Stanford University School of Medicine announced on Saturday the results of the Apple Heart Study, a project that was first announced in November 2017 and funded in full by the Cupertino, California, tech giant. While the study has yet to be published or peer-reviewed, as noted by CNN, the findings suggest that the Apple Watch could be potentially useful in detecting irregular heartbeats that might be a sign of atrial fibrillation.
According to a report from The Verge that cited both press releases, the Apple Heart Study involved a total of 419,093 people from all 50 states, who took part in the research over a span of eight months. As it was only released in September 2018, the Apple Watch Series 4, which comes with a built-in electrocardiogram (ECG), was not included in the study.
All in all, more than 2,000 individuals, or approximately 0.5 percent of all participants, were notified by their Apple Watches of irregularities with their heart rates over the eight-month study period. Those who received irregular heartbeat notifications were subjected to additional monitoring through digital consultations and ECG patches, either from the time the irregularities were detected or over a week later.
Based on comparisons between the Apple Watch’s detection of irregular heart rhythms and simultaneous ECG patch recordings, the wearable’s pulse detection algorithm had a 71 percent positive predictive value. Eighty-four percent of the participants who received notifications of irregularities on their Apple Watches were found to have atrial fibrillation at the time they were alerted by their devices.
Meanwhile, only 34 percent of those who received irregular heartbeat notifications and had ECG patch follow-ups after waiting more than a week were confirmed to be suffering from atrial fibrillation. Stanford Medical’s press release noted that it was “not surprising” that the condition was not detected in most cases after waiting over a week before follow-up, due to atrial fibrillation being intermittent in nature.
The Apple Heart Study also revealed that 57 percent of the participants who got irregular pulse notifications sought medical assistance from a professional.
— 9to5Mac.com (@9to5mac) March 16, 2019
“The study’s findings have the potential to help patients and clinicians understand how devices like the Apple Watch can play a role in detecting conditions such as atrial fibrillation,” read a statement from Dr. Mintu Turakhia, an associate professor of cardiovascular medicine at Stanford Medical School who served as the study’s co-principal investigator, per CNN.
Furthermore, the researchers described the above findings as important in the light of “over-notification” concerns from medical experts, who believe it might be counterproductive for consumers to receive an overload of health-related information from their smartwatches due to what they see as a strong possibility of “false positive” readings.
Despite the apparent accuracy of older Apple Watch models in flagging heart rate irregularities and the fact that the Apple Watch Series 4 has an ECG feature, The Verge cited Apple’s own warning that the latter device, in particular, should not be used as a substitute for diagnosis from a medical professional. The outlet further cautioned that smartwatches and fitness trackers, while capable of detecting irregularities, are not yet advanced enough to be considered 100 percent accurate.