Stanford Medicine has published the findings from its Apple Heart Study. The results show that 0.5% or some 2,000 of the 419,297 participants received irregular heart rhythm notifications.
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The project was launched about a year ago in conjunction with the release of Apple’s fourth generation smartwatch and watchOS 4. The research was created in part to assess the effectiveness of Apple Watch in spotting signs of atrial fibrillation (AFib).
Participants received access to a Heart Study app which uses algorithms to isolate heart rhythms from other noise. If an irregular heart rhythm was spotted, the participant received a free consultation with a doctor and an electrocardiogram (ECG) patch for further monitoring.
“We are proud to work with Stanford Medicine as they conduct this important research and look forward to learning more about the impact of Apple Watch alongside the medical community,” said Jeff Williams, Apple’s COO at the time.
“We hope consumers will continue to gain useful and actionable information about their heart health through Apple Watch.”
The study results were presented earlier this year at the American College of Cardiology’s 68th Annual Scientific Session and Expo. It is only now, though, they’ve been published in The New England Journal of Medicine.
The results showed that around 0.5% of the study participants received irregular heart rhythm notification over 117 days of monitoring, and 3% of those over 65. This equates to 2,161 individuals.
In those that returned the ECG patch that could be analyzed (about a quarter of them), 84% of their subsequent notifications were confirmed to be atrial fibrillation. This would indicate the Apple Watch can be used for this purpose. Some of the atrial fibrillation picked up by the watch was too infrequent to be detected by the patch, though. This does not necessarily indicate false positives as it could be a sign of early stages of the condition.
“Among participants who were notified of an irregular pulse, the positive predictive value was 0.84 (95% CI, 0.76 to 0.92) for observing atrial fibrillation on the ECG simultaneously with a subsequent irregular pulse notification and 0.71 (97.5% CI, 0.69 to 0.74) for observing atrial fibrillation on the ECG simultaneously with a subsequent irregular tachogram. Of 1376 notified participants who returned a 90-day survey, 57% contacted health care providers outside the study. There were no reports of serious app-related adverse events.”
Some people who have AFib don’t have any symptoms, so the condition often goes undiagnosed. Others may experience symptoms such as dizziness, weakness and fatigue. It is the first of these two groups which is particularly at risk.
According to the Centre for Disease Control and Prevention, around 2% of Americans under 65 have AFib, while about 9% of people 65 and older have AFib. So while the Apple Heart Study results are impressive, statistics would suggest the watch did not spot all instances of the condition.
Having said that, even if the device is not 100% accurate it will end up saving lives. Apple says more than half of participants in the study sought medical advice following their irregular rhythm notification.
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