Many patients (and perhaps physicians) are confused as to how best to utilize personal ECG devices. I received this question illustrating such confusion from a reader recently:
I first came across your website a year ago during persistent angina attacks, and returning now due to increasing episodes of symptoms akin to Afib. I bought a Kardia 2 yrs ago for the angina episodes, and looking to buy the Apple Series 4 for the Afib, as I want to try a wearable for more constant monitoring. What I would greatly appreciate if you had a basic guide for both the Kardia & Apple devices, specifically when and how to best employ them for unstable angina and detecting undiagnosed Afib. As in, what can I as a patient provide to you as a doctor for diagnosis in advance of a formal visit. I’m a US Iraq vet medically retired in the UK, and most of my concerns get dismissed out of hand as “anxiety”, not sure why they thought a stent would cure my anxiety though
First. please understand that none of these devices have any significant role in the management of angina. Angina, which is chest/arm/jaw discomfort due to a poor blood supply to the heart muscle cannot be reliably diagnosed by the single lead ECG recording provided by the Apple Watch, the Kardia Band or the Kardia mobile ECG device. Even a medical-grade 12 lead ECG doesn’t reliably diagnose angina and we rely on a constellation of factors from the patient’s history to advanced testing to determine how best to manage and diagnose angina.
Second, as you are having episodes “akin to Afib”, all of these devices can be helpful in determining what your cardiac rhythm is at the time of the episodes if they last long enough for you to make an ECG recording.
The single lead ECG recording you can make from the Apple Watch, the Kardia Band and from the Kardia mobile device can very reliably tell us what the cardiac rhythm was when you were feeling symptoms.
The algorithms of these devices do a good job of determining if the rhythm Is atrial fibrillation. Also, if the rhythm is totally normal they are good at determining normality.
These tracings can be reviewed by a competent cardiologist to sort out what the rhythm really is.
In all of these cases, having an actual recording of the cardiac rhythm at the time of symptoms is immensely helpful to your doctor or cardiologist in determining what is causing your problems.
My recommendation, therefore, would be to make several recordings at the time of your symptoms. Print them out and carefully label the print-out with exactly what you were feeling when it was recorded and present these to the doctor who will be reviewing your case.
As I’ve mentioned in previous posts (see here), my patients’ use of Kardia with the KardiaPro online service has in many cases taken the place of expensive and inconvenient long term monitoring devices.
Case Example-Diagnosing Rare And Brief Attacks Of Atrial Fibrillation
I recently saw a patient who I think perfectly demonstrates how useful these devices can be for clarifying what is causing intermittent episodes of palpitations-irregular, pounding, or racing heart beats.
She was lying on a sofa one day when she suddenly noted her heart “pumping fast” and with irregularity. The symptoms last for about an hour. She had noticed this occurred about once a year occurring out of the blue.
Her PCP ordered a long term monitor, a stress test and an echocardiogram.
The monitor showed some brief episodes of what I would term atrial tachycardia but not atrial fibrillation but the patient did not experience one of her once per year hour long episodes of racing heart during the recording. Thus, we had not yet solved the mystery of the prolonged bouts of racing heart.
She was referred to me for evaluation and I recommended she purchase an Alivecor device and sign up for the KardiaPro service which allows me to view all of her recordings online. The combination of the device plus one year of the KardiaPro service costs $120.
She purchased the device and made some occasional recordings when she felt fine and we documented that these were identified as normal by Kardia. For months nothing else happened.
Then one day in April she had her typical prolonged symptom of a racing heart and she made the recording below (She was actually away from home but had the Kardia device with her.)
When she called the office I logged into my KardiaPro account and pulled up her recordings and lo and behold the Kardia device was correct and she was in atrial fibrillation at a rate of 113 BPM.
With the puzzle of her palpitations solved we could now address proper treatment.
Continuous Monitoring for Abnormal Rhythms
Finally, let’s discuss the wearables ability to serve as a monitor and alert a patient when they are in an abnormal rhythm but free of any symptoms.
My reader’s intent was to acquire a device for “constant monitoring”:
I’m looking to buy the Apple Series 4 for the Afib, as I want to try a wearable for more constant monitoring.
This capability is theoretically available with Apple Watch 4’s ECG and with the Kardia Band (using SmartRhythm) which works with Apple Watch Series 1-3.
However, I have not been impressed with Apple Watch’s accuracy in this area (see here and here) and would not at this point rely solely on any device to reliably alert patients to silent or asymptomatic atrial fibrillation.
In theory, all wearables that track heart rate and alert the wearer if the resting heart rates goes above 100 BPM have the capability of detecting atrial fibrillation. If you receive an alert of high HR from a non ECG-capable wearable you can then record an ECG with the Kardia mobile ECG to see if it really is atrial fibrillation.
At 99$, the Kardia is the most cost-effective way of confirming atrial fibrillation for consumers.
I hope this post adds some clarity to the often confusing field of personal and wearable ECG devices.
The skeptical cardiologist recently received this email from a reader:
With the new Apple Watch that’s out now, people have suggested my husband (who had a heart attack at 36) should get it since it could detect a heart attack. But I keep remembering what you said – that these devices can’t detect heart attacks and that Afib isn’t related to a heart attack most of the time – is that still the case? I don’t really know how to explain to people that it can’t do this, since absolutely everyone believes it does.
The answer is a resounding and unequivocal NO!
If we are using the term heart attack to mean what doctors call a myocardial infarction (MI) there should be no expectation that any wearable or consumer ECG product can reliably diagnose a heart attack.
The Apple Watch even in its latest incarnation and with the ECG feature and with rhythm monitoring activated is incapable of detecting a myocardial infarction.
To make this even clearer note that when you record an ECG on the Apple Watch it intermittently flashes the following warning:
Note: “Apple Watch never checks for heart attacks”
How did such this idea take root in the consciousness of so many Americans?
Perhaps this article in 9-5 Mac had something to do with it
In reality, the man received an alarm that his resting heart rate was high at night. Apparently he also was experiencing chest pain and went to an ER where a cardiac enzyme was elevated. Subsequently he underwent testing that revealed advanced coronary artery disease and he had a bypass operation.
Even if we assume all the details of this story are accurate it is absolutely not a case of Apple Watch diagnosing an MI.
A high resting heart rate is not neccessarily an indicator of an MI and most MIs are not characterized by high heart rates. We have had the technology with wearables to monitor resting heart rate for some time and no one has ever suggested this can be used to detect MI.
The rate of false alarms is so high and the rate of failure to diagnose MI so low that this is a useless measure and should not provide any patient reassurance.
The writer of this story and the editors at 9-5 Mac should be ashamed of this misinformation.
Several other news sources have needlessly muddied the water on this question including Healthline and Fox News:
In clear cut cases the Apple Watch could make the difference between life and death,” says Roger Kay, president of Endpoint Technologies Associates. Because you wear the Apple Watch at all times, it can detect an early sign of a stroke or a heart attack, and that early indication is critical, he says.
And the Healthline article on the new Apple Watch also incorrectly implies it can diagnose MI:
The device, which was unveiled last week, has an electrocardiogram (ECG) app that can detect often overlooked heart abnormalities that could lead to a heart attack.
And if you are felled by a heart problem, the fall detector built into the Apple Watch Series 4 could alert medical professionals that you need help
Fox News and Healthline should modify their published articles to correct the misinformation they have previously provided.
And it is still true that although both Apple Watch and Kardia can diagnose atrial fibrillation the vast majority of the time acute heart attacks are not associated with atrial fibrillation.
Readers, please spread the word far and wide to friends and family-Apple Watch cannot detect heart attacks!
The results of the Apple Heart Study, were presented this morning at the American College of Cardiology Scientific Sessions amid intense media scrutiny. The AHS is a “prospective, single arm pragmatic study” which had the primary objective of measuring the proportion of participants with an irregular pulse detected by the Apple Watch who turn out to have atrial fibrillation on subsequent ambulatory ECG patch monitoring.
I and over 400,000 other Apple Watch owners participated in the AH study by downloading the Apple Heart Study app and self-verifying our eligibility.
My assessment is that we have learned little to nothing from the AHS that we didn’t already know. I’m also concerned that many patients suffered anxiety or unnecessary testing after being referred to urgent care centers, emergency departments, cardiologists or primary care providers and the results of these inappropriate referrals may never be determined.
Here is the study in a nutshell:
Participants enrolled by submitting information using the iPhone Heart Study app and none of their isubmitted nformation was verified.
An irregular pulse notification was issued to 0.5% of participants who were then contacted and asked to participate in a Telehealth visit with a doctor (who we will call Dr. Appleseed)
Only 945 of the 2161 who received a pulse notification participated in the first study visit.
Interestingly, Dr. Appleseed was empowered to send participants to the ER if they had symptoms (chest pain, shortness of breath, fainting/losing consciousness) It is not clear how many were sent to the ER and what their outcomes were but this flow diagram shows that 20 were excluded from further testing due to “emergent symptoms.”
Another 174 participants were excluded after finding out at the first visit that they had a history of afib or aflutter and 90 due to current anticoagulant use (both of these factors were exclusion criteria which gives us an idea of how accurate the information was at the time of participant entry.)
After all these exclusions only 658 ECG monitor patches were shipped to the participants of which only 450 were returned and analyzed.
This means of the original 2161 participants who were notified of pulse irregularity, the study only reports data on 450 or 21%. Such a low rate of participation makes any conclusions from the study suspect.
Of the 450 ECG patches analyzed only 34% were classified as having afib. Only 25% of this afib lasted longer than 24 hours.
After the patch data was analyzed, patients had a second Telehealth visit with Dr. Appleseed who reviewed the findings with the patient. Per the initial published description of the methods of the AHS (see here) Dr. Appleseed would tell the participant to head to the ER if certain abnormalities were found on the ECG.
Per the study description (apple heart study), Dr. Appleseed recommended a visit to the PCP for “AF or any other arrhythmia” detected by the patch:”
“If AF or any other arrhythmias have been detected in reviewing the ambulatory ECG monitor data, or if there are other non-urgent symptom identified by the study physician during the video visit that may need further clinical evaluation, the Study Telehealth Provider directs the participant to his or her primary health care provider”
At this point it seems likely that a lot of participants were instructed to go see their PCPs. Because as someone who looks at a lot of 2 week ambulatory ECG recordings I know that is the rare recording that does not show “other arrhythmias.”
Even more distressing is the call that participants would have received based on “the initial technical read:” I’m presuming this “technical read” was by a technician and not by a cardiologist. In my experience, many initial reads from long term monitors are inaccurate.
“If the initial technical read identifies abnormalities that require urgent attention (ventricular tachycardia or ventricular fibrillation, high-degree heart block, long pauses, or sustained and very rapid ventricular rates), then the participant is contacted immediately and directed to local emergency care or advised how to seek local emergency care.”
I wonder how many ERs had AHS participants show up saying they had been told they had a life-threatening arrhythmia? How much down stream testing with possible invasive, life-threatening procedures such as cardiac catheterization were performed in response to these notifications?
Overall, these findings add nothing to previous studies using wearable PPG technology and they certainly don’t leave me with any confidence that the Apple Watch is accurately automatically detecting atrial fibrillation.
Was more harm than good done by the Apple Heart Study?
We will never know. The strength of this study, the large number of easily recruited participants is also its Achilles heel. We don’t know that any information about the participants is correct and we don’t have any validated follow up of the outcomes. In particular, I’m concerned that we don’t know what happened to all of these individuals who were sent to various health care providers thinking there might be something seriously wrong.
Perhaps Apple and Stanford need to review the first dictum of medicine: Primum Non Nocere, First Do No Harm.
The Oura ring is a novel, multisensory device that claims to be able to distinguish sleep stages, including REM sleep,. I purchased one recently and after several months of evaluation and an extensive look at the data supporting it I have to say I am much more impressed with OURA’s hype, marketing and style than any useful or actionable information about sleep that comes from it.
The Oura website is full of pictures of cool people doing cool things wearing their Oura rings-like this guy
It’s also chock full of marketing blather which implies that somehow the ring will dramatically improve your sleep and your waking life.
We see every individual as unique: your state of health and wellness today, tomorrow, and days to follow. Getting enough restorative sleep has a profound impact on mental and physical health and performance. Your daily choices and rhythms define how well you sleep. With Oura, you learn your optimal times to move, eat and take a break to get that restorative sleep. Giving you actionable steps to improve your life opens a totally new universe of possibilities – be it for mental, cognitive or physical performance, or for beauty, health, and longevity.
A quick look at the OURA web site certainly conveys the sense that this is the slickest, most cutting edge personal wearable sleep and activity tracker one could purchase.
However, despite Oura’s tantalizing claims there is only one legitimate scientific comparison of the ring to the gold-standard of sleep evaluation, polysmnography (PSG). This was published in 2017 in Behavior Sleep Medicine and its full contents can be read here.
In addition, there is no published evidence whatsoever that changing one’s behaviour based on the various parameters that the ring produces will have any favorable effect on your sleep quality or health in general.
I’ll be quoting from that 2017 published paper which I think is a good, unbiased analysis and I’ll throw in some of my own observations throughout this piece.
How The Ring Works And What It Claims To Do
A good night’s sleep, everyone should know by now is incredibly important to optimal performance the next day. In addition poor sleep quality is linked to a whole host of pathologies (with causality yet to be proven for most.) Thus, I quickly purchased an OURAring after hearing Peter Attia rave about his ring.
OURA likes to promote the idea that it has some sort of special way of measuring sleep based on a combination of sensors.
The Oura ring and its proprietary algorithms are a combination of extensive scientific understanding, years of careful research and development work, and top-notch engineering. All insights and guidance you get are based on proven algorithms and verified knowledge. For example, Oura’s sleep staging algorithms were the first in the market that have been independently validated. The validation study was made by SRI International.
The OURA website notes that the ring is fitted with the following sensors to collect physiologic signals from your body.
NTC BODY TEMPERATURE SENSOR The Oura ring registers your body temperature reading every minute while you sleep. By comparing that value to values from earlier nights, it indicates your body temperature baseline and any variations from it.
INFRARED LEDS Measuring blood volume pulse directly from the palmar arteries of the finger.
3D ACCELEROMETER AND GYROSCOPE Detects the amplitude and intensity of your body movement, automatically recognizes that you’re active and tracks the time you were inactive during the day.
Ōuraring (Oulu, Finland) claims to use these physiological signals (a combination of motion, heart rate, heart rate variability, and pulse wave variability amplitude) in combination with sophisticated machine learning based methods to calculate deep (PSG N3), light (PSG N1+N2) and rapid-eye-movement (REM) sleep in addition to sleep/wake states.
After obtaining a sizing kit from OURA I selected my ring and within a few weeks it was delivered. I downloaded the free OURA iPhone app, charged the ring with the supplied USB charger, slipped it on my left ring finger and eagerly awaited my first night’s analysis.
Upon arising in the morning I opened the OURA app and visualized an entrancing display like the one below.
It’s a nice graphic summary of the night’s sleep with my minutes of REM, light, and deep sleep nicely quantified.
More graphs and more data are available by connecting to Oura’s online application which automatically syncs to your smartphone app.
Unfortunately, the app was telling me that I was awake for 109 minutes of the time I was in bed. Which was not correct. I was truly awake only for 10 minutes around 130 AM. This overestimation of my awake time has been a consistent error of the ring for my recordings. If the app can’t accurately track awake time all of its metrics are going to be inaccurate.
In fact, over several months of using the ring/app I have found little relationship between how I feel after sleeping versus how Oura has rated my sleep. There is even less correlation between the “readiness” score that Oura produces and how I feel during the day. Overall, I have found absolutely no actionable information from my months of using the ring.
One morning Oura gave me a “readiness” score of 68 and told me:
“Don’t push it. Your resting heart rate was above average, so you might not be fully recovered”
I felt great throughout the day. These recommendations in my experience are almost unversally inaccurate and useless.
Oura also makes recommendations on when it thinks you should go to bed. One time it told me I should go to bed at 7 PM. I have been ignoring its advice in this area.
Now I am just one individual and it is entirely possible there is something unique about my sleep that invalidates the ring’s accuracy. The ex-eternal fiancee’ tells me I’m a restless sleeper.
In fact, devices that rely on actigraphy tend to be fairly accurate at identifying when you are sleeping but not when you are awake which is the opposite of what OURA is doing in my case.
The SRI paper puts it this way
Compared to PSG, actigraphy has high sensitivity (ability to detect sleep) although specificity (ability to detect wakefulness) is lower(Marino et al., 2013; Sadeh, 2011), with a wide range of accuracy,depending on the amount of night-time wakefulness(Paquet, Kawinska, & Carrier, 2007),the algorithms used and the particular population studied(Van de Water, Holmes, & Hurley, 2011). Most importantly, actigraphy relies on a single sensor, an accelerometer, and thus it provides a measure of motion from which it predicts sleep and wake states. However, information about sleep stage composition, fundamental in studying sleep and sleep disorders,is not provided.
The Science Behind Oura’s Sleep Analytics: Detecting Sleep Stages
So what does the SRI paper OURA likes to quote as proving its accuracy say.
The paper is entitled “The Sleep of the Ring: Comparison of the ŌURASleep TrackerAgainst Polysomnography” and it was written by researchers at SRI international, a research consortium in Menlo Park, California with no ties to OURA.
Another paper which used to be touted on the Oura Ring website (but is no longer referenced on the site) utilized home PSG recordings and was done by an in-house OURA employee.
The SRI researchers studied 41 healthy adolescents and young adults with an average of 17 years and sleep data were recorded using the ŌURA ring and standard PSG on a single laboratory overnight. Metrics were compared using Bland-Altman plots and epoch-by-epoch (EBE) analysis.
EBE analysis showed that ŌURA accurately detected “light” and “deep” sleep in 65% and 51% of the epochs, respectively. It also accurately detected REM sleep epochs 61% of the time, with an overall overestimationof PSG REM sleep (by about 17 min). When the ŌURA ring misclassified PSG REM sleep, the algorithm classified the epoch as “light sleep” (76%) for the majority of the time.
These data suggest that the Oura Ring is virtually useless in telling you if you are in REM sleep versus deep or light sleep.
As the authors noted
Distinguishing sleep stages such as REM and N3 with non-EEG based systems has been challenging and is a goal of several commercial sleep-trackers, with mixed success.
Clearly, further work is needed to determine what combination of sensors might be used to optimally develop an algorithm that differentiates sleep stages sufficiently well to detect real differences or changes in healthy and clinical populations.
A look at the Bland-Altman plots really tells you how much variation there was in the PSG estimates of various parameters versus the OURA
The Bland-Altman plots show us how much the PSG time in REM differed from the Oura REM time for each individual subject. You can see that some individuals had considerable over-estimation of REM time whereas other had considerable overestimation of REM time.
Although OURA REM time was on average only 17 minutes higher than the PSG REM time this was because the marked overestimation of REM time in some (7 subjects over 30 minutes) was balanced by marked underestimation in others (9 subjects with over 40 minutes and one with 160 minutes).
Given that the average REM time was 92 minutes for most subjects there was a significant discrepancy between PSG. and OURA assessments.
OURA: Coin Flip For Detecting Awake
Oura ring was also pretty useless at identifying when you are awake
Overall, ŌURA had 96% sensitivity (ability to detect sleep), 48% specificity (ability to detect wake), 65% agreementin detecting “light sleep”, 51% agreementin detecting “deep sleep”, and 61% agreementin detecting REM sleep, relative to PSG
Like other sleep sensors utilizing actigraphy, Oura in most individuals can’t accurately differentiate between times when you are lying still but awake and when you are lying still and asleep.
The limitations of wrist actigraphy (see here) for differentiating sleep from wake are worse in those with insomnia:
With actigraphy, because sleep is inferred from lack of movement, subjects who are awake but lie motionless can be classified incorrectly as being asleep, and thus the technique is biased toward overestimating time to sleep, which may lead to incorrectly minimizing the severity of sleep disturbances. This may present a specific challenge for patients with insomnia, and may partially explain the limited validity of wrist actigraphy for estimating sleep onset latency..
There are multiple other issues and questions with the usefulness of the data that Oura provides that need clarifying before the ring can be considered useful.
For example the SRI paper found significant differences in results depending on which finger the ring was placed on.
Interestingly, we found that PSG-ŌURA discrepancies for “light sleep” and REM were greater on the ring finger compared to the other fingers, a result that was independent from the amount of PSG sleep fragmentation.Assuming that the main parameters that ŌURA uses to determine sleep stages are motion and optical sensor outputs, it is possible that the different blood supply among fingers maypartially explain these results. For example, it has been shown that SpO2 values differ between fingers as well as hands suggesting a finger-dependent difference in accuracy of the pulse oximetry signal (Basaranoglu et al., 2015).Further studies should confirm and better characterize the dependency of the PSG-ŌURA discrepancies on the ring position by having the same participants simultaneously wear different rings on different fingers.
The in-house Oura study also noted that results were more accurate on the non-dominant hand finger compared to the dominant hand but the Oura website makes no recommendation on which finger to use.
The other data that Oura compiles (heart rate, heart rate variability, temperature change, respirations) are clearly related to sleep cycles but Oura provides no evidence that these data or their proprietary algorithms to give you “readiness” or sleep quality scores are accurate or of any value.
Shold You Buy An Oura Ring?
If you are hoping to get improved analysis of your sleep quality I don’t think Oura adds anything to what is elsewhere available using cheaper wrist actigraphy devices.
The ring is expensive at 299$ and cannot accurately detect sleep stages.
Although most reviews you will encounter on the internet are wildly enthusiastic about Oura, they are likely biased and they provide no evidence that the unique aspects of the ring sensors provide useful information.
Would I buy it again?
I’ve misplaced my ring several times and I have to say that this distressed me immensely. Given that I think the sleep analysis is worthless this is hard to explain.
I think my attachment to the ring is due to a number of factors
It’s stylish and it mimics a wedding ring (which I otherwise would not have.)
I’m intrigued by some of the cardiovascular data it produces (night time heart rate and heart rate variability). Although currently I don’t think the data can guide me to healthier behavior, it’s possible that there is useful information in there somewhere. I hope to write a post on heart rate variability down the line. I’ve done research in this area and have some strong opinions on its value.
I’m curious to see if the respiratory rate data and the temperature data is of any value whatsoever.
So, the ring is best I would say for well-heeled,, self-hacking and self-experimenting techno geeks.
Apple claims that its Apple Watch can detect atrial fibrillation (AF) and appropriately notify the wearer when it suspects AF.
This claim comes with many caveats on their website:
Apparently it needs to record 5 instances of irregular heart beat characteristic of atrial fibrillation over at least 65 minutes before making the notification.
This feature utilizes the watch’s optical heart sensors, is available in Apple Watch Series 1 or later and has nothing to do with the Apple Watch 4 ECG recording capability which I described in detail in my prior post.
Failure To Detect AF
A patient of mine with known persistent AF informed me yesterday that she had gone into AF and remained in it for nearly 3 hours with heart rates over 100 beats per minute and had received no notification. She confirmed the atrial fibrillation with both AW4 recordings and AliveCor Kardia recordings while she was in it.
The watch faithfully recorded sustained heart rates up to 140 BPM but never alerted her of this even though the rate was consistently over her high heart rate trigger of 100 BPM.
The patient had set up the watch appropriately to receive notifications of an irregular rhythm.
Reviewing her tracings from both the AW4 and the Kardia this was easily diagnosed AF with a rapid ventricular response.
What does Apple tell us about the accuracy of the Apple Watch AF notification algorithm? All we know is the unpublished , non peer-reviewed data they themselves collected and presented to the FDA.
In a study of 226 participants aged 22 years or older who had received an AFib notification while wearing Apple Watch and subsequently wore an electrocardiogram (ECG) patch for approximately 1 week, 41.6% (94/226) had AFib detected by ECG patch. During concurrent wear of Apple Watch and an ECG patch, 57/226 participants received an AFib notification. Of those, 78.9% (45/57) showed concordant AFib on the ECG patch and 98.2 % (56/57) showed AFib and other clinically relevant arrhythmias. These results demonstrate that, while in the majority of cases the notification will accurately represent the presence of AFib, in some instances, a notification may indicate the presence of an arrhythmia other than AFib. No serious device adverse effects were observed
This tells us that about 80% of notifications are likely to be Afib whereas 20% will not be Afib. It is unclear what the “other clinically relevant arrhythmias” might be. If I had to guess I would suspect PVCS or PACS which are usually benign.
If 20% of the estimated 10 million Apple Watch wearers are getting false positive notifications of afib that means 2 million calls to doctor or visits to ERs that are not justified. This could be a huge waste of resources.
Thus the specificity of the AF notification is 80%. The other important parameter is the sensivitiy. Of the cases of AF that last >65 minutes how many are detected by the app?
Apple doesn’t seem to have any data on that but this obvious case of rapid AF lasting for 3 hours does not give me much confidence in their AF detection algorithms.
They do have a lot of CYA statements indicating you should not rely on this for detection of AF:
It is not intended to provide a notification on every episode of irregular rhythm suggestive of AFib and the absence of a notification is not intended to indicate no disease process is present; rather the feature is intended to opportunistically surface a notification of possible AFib when sufficient data are available for analysis. These data are only captured when the user is still. Along with the user’s risk factors, the feature can be used to supplement the decision for AFib screening. The feature is not intended to replace traditional methods of diagnosis or treatment.
My patient took her iPhone and Apple Watch into her local Apple store to find out why her AF was not detected. She was told by an Apple employee that the Watch does not detect AF but will only notify her if her heart rate is extremely low or high. I had asked her to record what they told her about the problem.
As I’ve written previously (see here) the Apple Watch comes with excessive hype and minimal proof of its accuracy. I’m sure we are going to hear lots of stories about AF being detected by the Watch but we need some published, peer-reviewed data and we need to be very circumspect before embracing it as a reliable AF monitor.
My first patient this morning, a delightful tech-savvy septagenarian with persistent atrial fibrillation told me she had been monitoring her rhythm for the last few days using her Apple Watch 4’s built in ECG device.
I had been eagerly awaiting Apple’s roll out since I purchased the AW4 in September (see here) and between patients this morning I down-loaded and installed the required iPhone and Watch upgrades and began making AW4 recordings.
Through the day I tried the AW4 and the Kardia on patients in my office.
Apple Watch 4 ECG Is Easy and Straightforward
The AW4 ECG recording process is very easy and straightforward. Upon opening the watch app you are prompted to open the health app on your iPhone to allow connection to the Watch ECG information. After this, to initiate a recording simply open the Watch ECG app and hold your finger on the crown.
Immediately a red ECG tracing begins along with a 30 second countdown.
Helpful advice to pass the time appears below the timer:
“Try Not to move your arms.”
“Apple Watch never checks for heart attacks.”
When finished you will see what I and my patient (who mostly stays in sinus rhythm with the aid of flecainide) saw-a declaration of normality:
Later in the day I had a few patients with permanent atrial fibrillation put on my watch.
This seventy-something farmer from Bowling Green, Missouri was easily able to make a very good ECG recording with minimal instruction
The AW4 nailed the diagnosis as atrial fibrillation.
We also recorded a Kardia device ECG on him and with a little more instruction the device also diagnosed atrial fibrillation
After you’ve made an AW4 recording you can view the PDF of the ECG in the Health app on your iPhone where all of your ECGs are stored. The PDF can be exported to email (to your doctor) or other apps.
Apple Watch Often “Inconclusive”
The AW4 could not diagnose another patient with permanent atrial fibrillation and judged the recording “inconclusive”
The Kardia device and algorithm despite a fairly noisy tracing was able to correctly diagnose atrial fibrillation in this same patient.
I put the AW4 on Sandy, our outstanding echo tech at Winghaven who is known to have a left bundle branch block but remains in normal rhythm and obtained this inconclusive report .
Kardia, on the other hand got the diagnosis correctly:
One Bizarre Tracing by the AW4
In another patient , an 87 year old lady with a totally normal recording by the Kardia device, the AW4 yielded a bizarre tracing which resembled ventricular tachycardia:
Despite adjustments to her finger position and watch position, I could not obtain a reasonble tracing with the AW4.
The Kardia tracing is fine, no artifact whatsoever.
What can we conclude after today’s adventures with the Apple Watch ECG?
This is an amazingly easy, convenient and straightforward method for recording a single channel ECG.
I love the idea that I can record an ECG whereverI am with minimal fuss. Since I wear my AW4 almost all the time I don’t have to think about bringing a device with me (although for a while I had the Kardia attached to iPhone case that ultimately became cumbersome.)
Based on my limited sample size today, however, the AW4 has a high rate of being uncertain about diagnoses. Only 2/3 cases of permanent atrial fibrillation were identified (compared to 3/3 for the Kardia) and only 4/6 cases of sinus rhythm were identified.
If those numbers hold up with larger numbers, the AW4 is inferior to the Kardia ECG device.
I’d rather see the AW4 declare inconclusive than to declare atrial fibrillation when it’s not present but this lack of certainty detracts from its value.
What caused the bizarre artifact and inconclusive AW4 tracing in my patient is unclear. If anybody has an answer, let me know.
We definitely need more data and more studies on the overall sensitivity and specificity of the AW4 and hopefully these will be rapidly forthcoming.
For most of my patients the advantages of the AW4 (assuming they don’t already have one) will be outweighed by its much greater cost and we will continue to primarily utilize the Kardia device which will also allow me to view all of their recordings instantaneously in the cloud.
Note. The original version of this post had the wrong ECG tracing for the first “inconclusive” AW4 recording of a patient with permanent atrial fibrillation. H/t to discerning reader Vignesh for pointing this out months after the initial posting.
I described in detail in March (see here) my early experience in utilizing AliveCor’s KardiaMobile ECG device in conjunction with their Kardia Pro cloud service to monitor my patient’s with atrial fibrillation (afib). Since that post the majority of my new afib patients have acquired the Kardia device and use it regularly to help us monitor their afib.
This capability has revolutionized my management of atrial fibrillation. In those patients who choose to use AliveCor there is really no need for long-term monitors (Holter monitors, Zio patches, cardiac event monitors) and no need for patients to come to the office to get an ECG when they feel they have gone into afib.
When one of my Kardia Pro patients calls with symptoms or concern of afib, I quickly pull up their chart at Kardiapro.com and review their recordings to determine if they are in or out of rhythm. Most treatment decisions can then be handled over the phone without the need for ordering a monitor or an emergency room or office visit.
One 24 hour period will suffice to show how important KardiaPro is now to my management of my patients with afib
A Day In The Afib Life
Tuesdays I spend the day working in the heart station at my hospital. Typically, on these days I will supervise stress tests, read ECGs and echocardiograms, perform TEES and electrical cardioversions. On a recent Tuesday I had 3 patients scheduled for cardioversion of their atrial fibrillation.
The day before one of these patients called indicating that he suspected he had reverted back to normal rhythm (NSR) based on his Kardia readings. He had had a prior cardioversion after which we know (thanks to daily Kardia recordings) he reverted to afib in 5 days. Subsequently we had started him on flecainide, a drug for maintenance of NSR and scheduled him for the cardioversion.
Not uncommonly after starting flecainide patients will convert to NSR but if they don’t we proceed to an electrical cardioversion.
I logged into KardiaPro and reviewed his dashboard and sure enough his last two ECGs showed sinus rhythm. I congratulated him on this and we canceled his cardioversion for the next day, saving the lab the time and expense of a cancellation the day of the procedure. The patient avoided much stress, time and inconvenience.
It is important to note that in this patient there was no great jump in heart rate with afib compared to NSR. For many patients the rate is much higher with the development of afib and this is often detected by non ECG wearable monitors (like an Apple Watch.) But for patients like this one, an ECG is the only way to know what the rhythm is.
A second patient with afib who had elected not to acquire an AliveCor ECG device showed up for his cardioversion on Tuesday and after evaluating his rhythm it was clear he had spontaneously reverted back to NSR. Prior to my adoption of KardiaPro this was a common and scenario.
The third scheduled cardioversion of the day showed up in afib and we successfully cardioverted him back to NSR. I had not addressed utilizing AliveCor with him. Prior to the procedure he asked me about likely outcomes.
My standard response to this question is that we have a 99.9% success rate in converting patients back to NSR at the time of the cardioversion. However, I can’t predict how long you will stay in NSR after the cardioversion. NSR could last for 5 days or it could last for 5 years. Adding medications like flecainide or amiodarone can significantly reduce the risk of afib recurrence after cardioversion.
At this point he asked me “How do I know if I am in afib?” Whereas many afib patients immediately feel bad and are aware that they have gone out of rhythm, this man like many others was not aware.
Prior to AliveCor my answer would have been to check the pulse daily or look for evidence of high or irregular heart rates on BP monitors or fitness wearables. This scenario provided a wonderful opportunity to test the AliveCor’s accuracy at detecting AF in him. I pulled out my trusty AliveCor mobile ECG and prior to the cardioversion we made the recording below
After the cardioversion we repeated the Alivecor recording and the rhythm (AliveCor’s interpretation) had changed from afib to NSR.
Needless to say, this patient purchased a Kardia device the next day and since the cardioversion he’s made a daily recording which has confirmed NSR. I just logged into Kardia Pro and sure enough he made a recording last night and it showed NSR.
Later in the week I received a call from a patient I had electrically cardioverted a few days earlier. His Kardia device had detected that he had gone back into afib.
I logged into my Mac and saw his KardiaPro chart below.
With perfect precision KardiaPro had verified NSR after the cardioversion lasting for 36 hours. For some reason after dinner the day after the cardioversion, the patient had reverted back to afib. This knowledge greatly facilitates subsequent treatment and eliminates the need for in office ECGs and long term monitors.
Utilization of the Kardia device with the Kardia Pro monitoring service has proved for me to b a remarkable improvement in the management of patients with afib. Managing non Kardia afib patients feels like navigating a forest with a blindfold.
The improvement is so impressive that I find myself exclaiming to my assistant, Jenny, several times a week “How do other cardiologists intelligently care for afibbers without AliveCor?”
I have a few patients who balk at the 15$ per month charge for Kardia Pro and ask why the device and this monthly charge aren’t covered by insurance or Medicare. Given the dramatic reduction that I have noticed in my use of long-term monitors as well as office and ER visits in this population, CMS and third-party insurers would be wise to explore Kardia monitoring as a more cost-effective way of monitoring afib patients.
N.B. I realize this post appears to be an unmitigated enthusiastic endorsement of a commercial product which is quite uncharacteristic for the skeptical cardiologist.
One might wonder if the skepcard is somehow biased or compensated for his endorsement of Kardia.
In all honesty, this sprung from my love of the device’s improvement in my afib management and I have received no payment, monetary or otherwise from AliveCor and I own none of their stock (and I’m not even sure if it is on the stock market.)
One of my patients has been on the cutting edge of personal cardiac monitoring devices and I asked him to share his recent experience with the QardioCore ECG strap. What he sent me is a fascinating description of how the device works (which is unique in this area) along with how it was crucial in diagnosing the cause of his recent symptoms. I’m sharing it below.
“QardioCore is a clinical-quality wearable electrocardiogram recorder. An electrocardiogram – often abbreviated as ECG or EKG – is a test that measures the electrical activity of the heart. With each heart beat, an electrical impulse (or “wave”) travels through the heart. This wave causes the muscle to squeeze and pump blood from the heart.
An ECG gives two major kinds of information. First, by measuring time intervals on the ECG, a doctor can determine how long the electrical wave takes to pass through the heart. Finding out how long the wave takes to travel from one part of the heart to the next shows if the electrical activity is normal or slow, fast or irregular. Second, by measuring the amount of electrical activity passing through the heart muscle, a cardiologist may be able to find out if parts of the heart are too large or are overworked. During an ECG, several sensors, called electrodes, capture the electrical activity of the heart.
QardioCore is ideal for health conscious individuals or those with known or suspected heart conditions to record their everyday ECGs, physical activity, sport performance and medical symptoms and share their data with their doctors. Medical professionals can use QardioCore to quickly assess heart rate and rhythm, screen for arrhythmias, and remotely monitor and manage patients who use QardioCore.
QardioCore should be only used in conjunction with professional medical advice, diagnosis, or treatment, and not as a substitute, or a replacement for it. Qardio creates products and services that conform to US quality, safety and security requirements for medical products, while delivering a modern user experience. QardioCore will begin selling in the US after receiving US Food and Drug Administration clearance.”
Unfortunately, the US FDA tends to move slowly, and we can only speculate as too why, but the device is not available for purchase here. However, I found a friend in France who purchased one for me and shipped me the device. It is not illegal for me to use the device here, but it is not allowed to be sold here in the US.
I use an Apple I-Phone 8Plus and have used both the AliveCor KardiaBand and the KardiaMobile found here (https://store.alivecor.com), and reviewed by the esteemed Skeptical Cardiologist in other posts as well. While I find it as a useful tool, my only dissatisfaction is that I want to passively monitor my heart during sporting activities and look for rhythm disturbances. While I’m no expert in either sporting activities or rhythm disturbances, I’ve completed some healthy reading and living on both subjects and have a general awareness of the topic.
The QardioCore device is simple to wear, comes with three belts that can be used and cleaned, and comes with a charging cable. Everything that the app, and the product does, seems to be accurately described on their web site, so I won’t cover off on details here. You can read more about it at this link: https://www.getqardio.com/qardioapp/My only dissatisfaction with this device, and other blue tooth devices, has nothing to do with the device itself. Apple seems to randomly disconnect from Bluetooth devices with their phones. I don’t pretend to know the specific mechanisms for the problem, but my blue tooth devices for bicycling, music headsets, and heart monitoring have all been plagued with intermittent blue tooth connection problems. So, at times, I find myself having to restart their app to keep the device connected, which is a minor annoyance.
I also use the QardioArm product to measure and monitor my blood pressure and am satisfied with it as well.
What follows is my anecdotal experiences of September 26, 2018 through the present day and I agreed to write about them here, in case it provides useful insight to others in some way.
As a person with a short-term history of heart problems, I tend to capture a lot of data with my devices. I monitor things like heart rate variability, blood pressure, Alivecor Kardia readings, sleep history, etc. I make an active attempt to monitor my levels of stress, but I know for certain that I lead a stressful life.I work longer hours than I should, probably sleep less than I should, exercise less than I like and should, and medicate and pray far less than I should.So, I don’t want to imply that anything that happened is the fault of the medical system, bad blue tooth connections, bad medical care, or bad advice from the Skeptical Cardiologist or any other medical professional. I tend to listen well, learn well, but I don’t always act as I should.But, I’m responsible for my choices, my decisions, and I live with the results of my actions.
With that said, I was sitting at the office on Wednesday September 26th, 2018 and was working away without a care in the world. As a computer programmer, I’m very sedentary and enjoy my work. I was wearing my QardioCore ECG strap at the time because I’m a big believer in capturing baseline data for my general living and lifestyle. I believe this data was invaluable in my first episode of heart problems, but have no supporting evidence to support my claim. At around 8:58:42 AM, I felt somewhat bad, and felt my heart racing. I glanced over at my phone which was showing the ECG trace at the time and noticed what I believed was Atrial Flutter at the time. But, after about 20 seconds, the ECG trace returned to normal, and I felt fine again. I made a quick note of the time, because I was busy, and continued working for the day.The Quardio App provides no diagnostic information, so it doesn’t analyze and interpret ECG patterns like the Alivecor Kardia app does. When I arrived at home later that day, I went back to look at the ECG trace, as the Quardio App easily allows that through features of the App. When I found the point in time of the ECG, I became concerned immediately because I believe that I was seeing a pattern that I recognized as Ventricular Tachycardia, a condition that comes in many forms, and has many causes, but can be fatal if not properly treated. As my cortisol levels increased, I contacted Dr. Google and just quickly verified that I wasn’t completely nuts, although I acknowledge there may be some partial nuttiness there. While going through this process, I experienced another 4 second episode which only increased my anxiety levels. After contacting my wife and asking her to return home, and informing some family members, I felt it best that I should contact the Skeptical Cardiologist after hours for input on my problem. I hate to bother the doctor, as he is a busy man, but contacted his after-hours number.While the operator on the other end of the line wondered what kind of nut case I was, she kindly contacted the doctor who promptly called me on my cell phone.I had informed the kind doctor that I had the device about three weeks prior, so he was already aware that I had the QardioCore. I quickly informed the doctor that I believed I had experienced at least one but possibly two cardiac events. After briefly talking, I hung up the phone and texted him photos of the screens from the Quardio App, so he could see the ECG tracings. Here are the photos that I sent to the Skeptical Cardiologist via text:
I believe this tool is valuable in many ways, but I believe that it was helpful for the Skeptical Cardiologist, as it helped narrow our focus of blood tests, scans, and potential procedures to run in a faster than normal basis. Normally, if I had not had evidence (accurate or not), I would have had to schedule an appointment, or go to ER. At that point, they would have either ordered an event monitor for me to wear while I was away from the hospital, or they would have had to admit me. Since I had a past history of Atrial Fibrillation, which isn’t quite as serious, we would have been sent home with an event monitor and instructions to take it easy and continue to take meds. We would have run more blood work, and more scans, but the point is that we would have been more broadly focused, as we would have had to generally guess as to the nature of the event and narrow it down.
I recognize that this is one of the controversies that is active in clinical cardiology, as I listen to podcasts by Dr. John Mandrola and others regarding the latest cardio devices, procedures and research. I realize that many Cardiologists are not in favor of devices like these, because they lead to uninformed conclusions, which leads to unneeded stress on both patients and their stressed-out doctors and cardiologists. I’ve listened to both sides of the argument, and I have my own opinions that I won’t express here. I will just say that I believe that this device saved me time, possibly my life (as I don’t know what I don’t know, unless I know to look), and some time in hastening and narrowing my therapy choices.
I will say that my wife and I were extremely happy with the services provided by his staff, himself, his colleagues, and the hospital staff as well. While I am confident I may be considered a difficult patient by some, or many, they were very thorough and kind in their treatment and explanation of my treatment options.
I hope that my experience adds helpful insight to the discussion. I’m confident that the Skeptical Cardiologist will add to this post, with his views on the events I’ve discussed above. And, I believe he appreciates having a Skeptical Patient every now and then as well.
As The Skeptical Patient wrote, this device is not sold in the United States. Having seen it in action now, I’m eager to get my hands on one and evaluate it further. It could dramatically alter home arrhythmia monitoring. For this patient it was incredibly helpful. If any of my European or Australian readers has experience with it please let me know.
Qardio makes a stylish, accurate and portable home BP monitor that I’ve written favorably about here.
N.B. Featured image of man running on beach with QardioCore is not of my patient.
The skeptical cardiologist picked up an Apple Watch 4 at the Galleria Apple Store in St. Louis today. The Apple employee who retrieved it told me that ECG recording capabilities were expected in the fall. Of course fall began today and it is not at all clear when, if ever, Apple will provide the software update to its AW4 that will provide ECG capabilities.
Fortunately, consumers already have the capability of recording a medical grade single lead ECG with any Apple Watch 2 or 3-using the KardiaBand from AliveCor.
Apple has hubristically proclaimed the AW4 as the ultimate guardian of our health and while setting it up I was asked if I wanted the watch to notify me if my heart rate dropped below 40 bpm for 10 minutes. Sure! Let’s see how irritating this feature will be.
After setting up the new watch I immediately attached my KardiaBand and installed the Kardia Apple Watch app.
I was able to open the Kardia app and it performed its normal SmartRhythm monitoring but when I tried to record an ECG, alas, nothing happened.
It appears that the KardiaBand does not work with the new Apple Watch 4. Yet.
I was informed by Ira Bahr at AliveCor that their “testing on AW4 is not yet complete. So at present, the device is not supported.”
Now I face a difficult decision-Do I wear my new AW4 with a non KardiaBand wrist band (and no ECG capability) or wear my old Apple Watch with the KardiaBand (and outstanding ECG capability.)
As I pointed out Friday, Apple’s claim that the ECG sensor on their new Apple Watch 4 (available “later this year”) is “the First ECG product offered over the counter directly to consumers” is totally bogus.
AliveCor’s Kardia mobile ECG device was approved by the FDA for over the counter direct to consumer sales on February 10, 2014. Apple had to have known this as they worked with AliveCor to bring the first Apple Watch based ECG device to FDA approval in 2017.
I tried but failed to get AliveCor founder Dr. David Albert’s thoughts on Apple’s disinformation but Yahoo finance was able to speak to Vic Gundotra, the CEO of AliveCor:
Over at the headquarters of AliveCor, a startup based in Google’s hometown of Mountain View, they, too, were surprised by the announcement, CEO Vic Gundotra said in a phone interview on Thursday. Gundotra is a former Googler, widely known as the executive behind the Google+ social network.
Gundotra was also surprised by Apple’s claims of ECG primacy
“We were watching [the announcement], and we were surprised,” Gundotra said. “It was amazing, it was like us being on stage, with the thing we’ve been doing for 7 years,” referring to AliveCor’s product for detecting atrial fibrillation (AFib), a tough-to-spot heart disorder that manifests as an irregular, often quick heart rate that can cause poor circulation.
“Although when they said they were first to go over-the-counter, we were surprised,” he continued. “Apple doesn’t like to admit they copy anyone, even in the smallest things. Their own version of alternative facts.”
One man’s alternative fact is another (less polite) man’s lie.
Gundotra apparently views Apple’s entry as a good thing
“We love that Apple is validating AFib; just wait until you see what AliveCor is going to do next,” he said. “We were a great restaurant in a remote section of town, and someone just opened a giant restaurant right next to us, bringing a lot more attention.”
And as I pointed out previously, the AliveCor mobile ECG device (not the Kardia Band) is significantly cheaper than an Apple Watch and has multiple studies showing its accuracy. Interestingly, Gundotra indicates AliveCor sales has increased after the Apple announcement,.
“Ours is $99, theirs is $399, our sales popped yesterday, big time,”