Apple Heart Study – The Early Career Voice

Can artificial intelligence save our lives?

January 2, 2020January 2, 2020 Noora Alhajri, MD, MPH

The role of artificial intelligence (AI) in our life is advancing rapidly and is making strides in early detection of diseases. The consumer market is composed of wearable health devices that enables continuous ambulatory monitoring of vital signs during daily life (at rest or physical activity), or in a clinical environment with the advantage of minimizing interference with normal human activities¹. These devices can record a wide spectrum of vital signs including: heart rate and rhythm, blood pressure, respiratory rate, blood oxygen saturation, blood glucose, skin perspiration, body temperature, in addition to motion evaluation. However, there is a lot of controversy whether these health devices are reliable and secure tools for early detection of arrhythmia in the general population².

Atrial fibrillation (afib) is the most common arrhythmia currently affecting over 5 million individuals in the US and it’s expected to reach almost 15 million people by 2050. Afib is associated with an increased risk of stroke, heart failure, mortality and represents a growing economic burden³. Afib represents a diagnostic challenge, it is often asymptomatic and is often diagnosed when a stroke occurs. Afib represents also a long term challenge and often involves hospitalization for cardioversion, cardiac ablation, trans-esophageal echo, anti-arrhythmic treatment, and permanent pacemaker placement. However, if afib is detected, the risk of stroke can be reduced by 75% with proper medical management and treatment³.

Physicians need fast and accurate technologies to detect cardiac events and assess the efficacy of treatment. A reliable, convenient and cost-effective tool for non-invasive afib detection is desirable. Several studies assessed the efficacy and feasibility of wearable technologies in detecting arrhythmias. The Cleveland clinic conducted a clinical research where 50 healthy volunteers were enrolled. They tested 5 different wearable heart rate monitors including: (Apple Watch, Garmin Forerunner, TomTom Spark Cardio, and a chest monitor) across different types and intensities of exercises (treadmill, stationary bike and elliptical). The study found that chest strap monitor was the most accurate in tracking the heart rate across different types and intensities of exercises⁴.

The Apple and Stanford’s apple Heart Study enrolled more than 419,297 Apple Watch and iPhone owners. Among these users 2,161 (roughly 0.5%) received a notification of an irregular pulse. Of those who received the notifications, only about 450 participants scheduled a telemedicine consultation and returned a BioTelemetry ECG monitoring patch. When the Apple Watch notification and ECG patch were compared simultaneously, researchers found 71% positive predictive value and about 84% of the cases were experiencing Afib at the time of the alert. Additionally, in 34% of participants whose initial notification prompted an ECG patch delivery were later diagnosed with Afib. This finding shows that Apple watch detected afib in about one third of the cases which is “good” for a screening tool considering the “intermittent nature of afib and that it may not occur for a whole week” says Dr. Christopher Granger, a professor of medicine at Duke University who participated on the steering committee for the Apple Heart study⁵.

These studies are observational studies and are not outcome driven. They are not randomized and are not placebo controlled. There are potentials for false negatives, where the Apple watch fails to detect the afib and false positive where it detects arrhythmia that does not exist. Unfortunately, patients who are false negative don’t consult the physician about their symptoms of palpitations and shortness of breath since it provides false security. While patients with false positive are sent unnecessarily to the clinic that could lead to further unnecessarily test and anxiety for the patient.

Is the Apple Watch ready to be used as a default screening tool to monitor the heart rate and rhythm in the general population and by physicians with patients with or at high risk for Afib is still unclear and warrant further studies. In conclusion, physicians should be cautious when using data from consumer devices to treat and diagnose patients.

References:

Cheung, Christopher C., Krahn, Andrew D., Andrade, Jason G. The Emerging Role of Wearable Technologies in Detection of Arrhythmia. Canadian Journal of Cardiology. 2018;34(8):1083-1087. doi:10.1016/j.cjca.2018.05.003
Dias D, Paulo Silva Cunha J. Wearable Health Devices-Vital Sign Monitoring, Systems and Technologies. Sensors (Basel). 2018;18(8):2414. Published 2018 Jul 25. doi:10.3390/s18082414
Chugh, S., Sumeet, Havmoeller, J., Rasmus, Narayanan, F., Kumar, et al. Worldwide Epidemiology of Atrial Fibrillation: A Global Burden of Disease 2010 Study. Circulation. 2014;129(8):837-847. doi:10.1161/CIRCULATIONAHA.113.005119
Wrist-Worn Heart Rate Monitors Less Accurate Than Standard Chest Strap. Medical Design Technology. http://search.proquest.com/docview/1875621494/. Published March 9, 2017.
Turakhia, Mintu P., Desai, Manisha, Hedlin, Haley, et al. Rationale and design of a large-scale, app-based study to identify cardiac arrhythmias using a smartwatch: The Apple Heart Study. American Heart Journal. 2019;207:66-75. doi:10.1016/j.ahj.2018.09.002

The views, opinions and positions expressed within this blog are those of the author(s) alone and do not represent those of the American Heart Association. The accuracy, completeness and validity of any statements made within this article are not guaranteed. We accept no liability for any errors, omissions or representations. The copyright of this content belongs to the author and any liability with regards to infringement of intellectual property rights remains with them. The Early Career Voice blog is not intended to provide medical advice or treatment. Only your healthcare provider can provide that. The American Heart Association recommends that you consult your healthcare provider regarding your personal health matters. If you think you are having a heart attack, stroke or another emergency, please call 911 immediately.

Wearables in Medicine: Try It Before You Prescribe It?

April 3, 2019April 3, 2019 Jeffrey Hsu, MD, PHD

Much of the “buzz” in the air among ACC19 attendees revolved around the Apple Heart Study. There was a wide variety in reactions to the study results – from underwhelmed to measured to overzealous. After some reflection, my personal reaction is that I’m just glad this study was performed – now we have some data for one of the most widely used wearable devices by our patients. Patients will, and already have, come to me with questions about the Apple Watch and its heart rhythm monitoring capabilities, and now I have some numbers available to help me address their concerns.

As the Apple Heart Study is likely just the beginning of an impending flood of wearable and virtual enrollment studies, physicians will undoubtedly be asked more and more questions about data collected by our patients’ devices. Just the other week in clinic, I had one new patient present with concerns about his cycling performance over the past few months. I fortunately noticed he was wearing an Oura ring device, and I asked him if he wore the ring during his cycling rides. He was shocked – he had yet to encounter a physician who knew what the Oura ring was, let alone be comfortable with analyzing the variety of data it measured. Fortunately, I had just chatted at length with a colleague who uses the Oura ring, as I was in the market for a wearable fitness monitor at the time. Yet even my cursory knowledge of the device seemed to deepen the patient-physician relationship in that first clinic visit.

The primary objective of the Apple Heart Study was to test the ability of the Apple Watch and its rhythm analysis algorithm to accurately detect atrial fibrillation. While atrial fibrillation detection is clearly an important tool, as recently described by AHA blogger, Dr. Christa Trexler, there are a variety of data being collected by wearables that may have tremendous value for our ability to optimally care for our patients, as these measurements lend insight into the 99+% of the time our patients spend outside of our clinic room with us. These include routinely measured factors (such as heart rate, step counts, and even blood pressure), but they are also measuring parameters and providing assessments of factors we do not routinely use in clinical practice, such as heart rate variability (HRV), “sleep quality,” and recovery/readiness indices. So, should we start incorporating these latter measurements in our patient care?

Figure: (Left) Apple Watch Series 4. (Right) Whoop Strap 2.0, demonstrating my Recovery Score for the day (based on my recent sleep patterns and recent cardiovascular workloads). (Both) Demonstration of probably wearing too many wearable devices.

As I mentioned, I was in the market for a wearable device, and somehow I now have two: the Apple Watch Series 4 and the Whoop Strap 2.0 (Figure 1). Overkill? Absolutely. But in experimenting with these devices, I’ve become incredibly fascinated with the HRV, sleep quality scores, and recovery. These are metrics that counterbalance our typical recommendations of increased physical activity with adequate rest and recovery. However, while parameters such as HRV were heavily studied in the 1990s and remain very much present in the current literature (search for “heart rate variability” on Pubmed yields 1665 publications), we have not routinely interfaced with these parameters in modern cardiology practice.

Yet I’ve found myself poring over my own device-measured physiological data and have already used it to plan my days. For instance, when my Whoop strap notifies me that I’m “in the green” and adequately recovered (as in Figure 1), I plan a more intense workout. Conversely, when I haven’t had adequate sleep for consecutive nights, I will be reminded by the Whoop app that my body is not primed for significant strain, and I will focus my efforts on restorative exercises, such as stretching and an early bedtime. While it seems silly to rely on a device to tell me how my body should feel, it has at the very least strengthened my own practice of reflecting on my health daily, a practice that can easily be forgotten amid busy clinical and research training.

With the increasing popularity and use of these wearables, and now that Apple Heart Study has paved the way for massive amounts of patients to be enrolled in studies using wearables, more of our patients will be using the Apple Watch, the Whoop strap, and other similar devices. To better prepare for this inevitable influx of personalized data, I feel that it is useful for clinicians to have our own experiences with these devices and apps. In my own experience, I’ve seen it enhance clinic encounters with patients, and by learning more about how devices monitor my own physiology, I believe it can help me better counsel my patients on how to monitor theirs.

What wearables do you use? Has your own use of wearables already impacted your management of patients? Would love to hear your thoughts via Twitter @JeffHsuMD.

The Future of Wearable Technology & Detecting Atrial Fibrillation – An Update!

April 1, 2019April 1, 2019 Christa Trexler, PhD

Last November at AHA18, I was lucky enough to catch a talk from one of the investigators, Dr. Marco Perez, working on the Apple Heart Study, where he described the goals of the project. I even wrote about it for the blog I wrote at AHA18 in Chicago, which you can find here.

To quickly recap, this unprecedented collaboration between Apple and Stanford is a progressive clinical trial that uses data from Apple Watch devices from over 400,000 participants. The main purpose of this study was to examine if atrial fibrillation (AFib) can be reliably diagnosed from irregular pulse notification data from wearable devices. In November, Dr. Perez mentioned that they wouldn’t have data until early 2019, and this past March, they released some results that are really exciting.

Highlights from the findings include:

Around 0.5% of participants received irregular pulse notifications, which was particularly important since people were concerned that these devices would potentially over-notify people.
The pulse detection algorithm of the Apple Watch has a 71% positive predictive value – this was compared to simultaneous electrocardiography patch recordings.
The majority of the time (84%) when participants received irregular pulse notifications, they were found to be in AFib at the time of the notification.
1/3 of the participants who received irregular pulse notifications and were then followed up by using an ECG patch over a week later were found to have AFib. This isn’t entirely surprising since AFib is an intermittent condition, so it’s not uncommon for it to go undetected in subsequent monitoring.
57% of people who received irregular pulse notifications sought medical attention afterwards.
A clinical trial could be conducted in this large-scale virtual manner

The last point is particularly important because this is the first study of its kind. It was almost completely virtual, at least from the standpoint that the researchers analyzing the data never once had any contact with the participants. Additionally, the scope of the number of people who were analyzed is impressive – 400,000 participants is quite the sample size, especially for someone like me who studies heart disease in mice!

Because AFib is an extremely common condition, affecting between 2-6 million people in the United States, that often goes undiagnosed, understanding that wearable technology can aid patients in detecting their condition is huge. Also, with the increase in technology in our health care sphere (specifically in cardiology), something that was expertly discussed by Dr. John Chen earlier this year on his blog is that this is just the beginning in understanding how wearable technology can help us treat disease. We now have another tool in our kit, and this one looks promising.

In Stanford’s press release, Dr. Perez said, “The performance and accuracy we observed in this study provides important information as we seek to understand the potential impact of wearable technology on the health system. Further research will help people make more informed health decisions.”

Interestingly, Johnson & Johnson and Apple recently announced their plans to build off these preliminary results by partnering together in a new project called HEARTLINE. This study will focus on an older population (~ 65 years) of around 150,000 participants who, due to their age, are at a higher risk of AFib. It’s a really exciting time to be in the cardiology field since this is just the beginning of this type of research, which is full of therapeutic potential.

It’s also really thrilling to be able to follow-up with this study, especially since it all started with my father-in-law, who has AFib, being nervous about using wearable technology to detect his condition. I’m excited to share this data with him as well since maybe he’ll feel a little more comfortable using it now.

Examples of the notifications that participants in the Apple Heart Study receive. Courtesy of Apple