Since it is common for AF to present at rates >120 BPM, AW ECG will fail to notify many (if not most) of its users that they are in AF.
AliveCor’s Kardia mobile ECG device (both the single lead and the six lead), on the other hand, has no problems identifying AF >120 BPM. I have found that the Kardia ECG was highly accurate in patients with rapid AF from using the device in hundreds of my patients since 2013.
After writing about the AW AF flaw I opened my KardiaPro dashboard which connects to the online ECG recordings each of my patients has made.
Two of my patients with paroxysmal AF had gone into AF in the last 2 days and made recordings.
Both of them had rates > 120 BPM. In both cases, Kardia had easily made the diagnosis. AW would have declared these “inconclusive.”
Patients should be aware of this AW AF flaw. The absence of a declaration of possible AF on the AW ECG should not reassure anyone of the absence of AF.
AW users should have their high rate recordings reviewed by a cardiologist.
Alternatively, they could purchase a Kardia device and utilize it for heart rates over 120 BPM.
The Apple Heart Study received great fanfare at least year’s AHA meetings and was subsequently published in the NEJM. Many Apple Watch (AW) wearers having heard of this study may have concluded the device will reliably identify atrial fibrillation (AF).
In my commentary on the Apple Heart Study I pointed out several issues with relying on Apple Watch for AF diagnosis, most significantly false positive notifications. Recent patient experiences have, in addition, made me concerned about false negative notifications and a lack of sensitivity.
AW ECG is inherently limited in diagnosing AF above 120 BPM. This guarantees a substantial number (possibly the majority) of AF episodes will not be recognized. Such false negative notifications may falsely reassure patients that they don’t have AF and delay them seeking medical attention.
Recently, I saw a patient who was referred to me for an abnormal 12-lead ECG. While reviewing his symptoms we discovered that his AW had registered high heart rates, sometimes up to 150 beats per minute, which lasted for several hours.
Although the AW had recorded this high heart rate it had not notified him of the possibility that he had atrial fibrillation or even that he had a high heart rate.
He had made the ECG recording below using the AW and the results came back inconclusive.
The AW ECG recording clearly shows atrial fibrillation going at a rapid rate-over 150 beats per minute-but the accompanying interpretation gives no hint that the patient had AF.
Based on the combination of an absence of any irregular heart rate/AF warnings from his AW and the absence of a diagnosis of AF when he made AW ECG recordings of the fast rates the patient assumed that he did not have atrial fibrillation.
Why is this? Apparently Apple has decided not to check for AF if the heart rate is over 120 BPM.
Given that most patients with new-onset AF will have heart rates over 120 BPM (assuming they are not on a rate slowing drug like a beta-blocker) it appears likely that Apple Watch ECG will fail to diagnose most cases of AF.
I asked my patient to record an ECG with his watch every time he felt his heart racing after our office visit. A few days later he was sitting in an easy chair after Thanksgiving watching TV and had another spell of racing heart. This time the heart rate was less than 120 BPM and the AW was able to analyze and make the diagnosis.
The inability of AW ECG to diagnose AF when the rate is >120 BPM further adds to my concerns about widespread unsupervised use of the device. When we combine inconclusive high heart rate analyses with the unknown sensitivity of the irregular heartbeat notification algorithm the AW may be providing many patients who have atrial fibrillation with a false sense of security.
Mark has subsequently undergone the ablation procedure and has kindly shared his thoughts and observations on the process. I’ve included a few comments (in green).
The Mystery of Afib and An Ablation
Everyone associated with afib knows how mysterious it seems to be. What triggers it? Why does it stop? Why does it affect marathoners, cross-country skiers, and NBA players more than other groups? Why is everyone’s experience as unique as popcorn granules? Recently Dr. Pearson invited me to talk about my accidental discover of afib, my unsuccessful cardioversions, and my decision to have an ablation.
In the last post, afib was affecting me every day when exercising. Moderate exercise would cause my heart to, as my electrocardiologist would say, “act like a drunken sailor.” It became hard. Exercise is important to me. Medication was not working for me. An ablation was the next step.
Choosing A Doctor
Before you decide on the cardiologist or electrophysiologist (EP) to perform an ablation, do research. Ablations are not particularly dangerous. No one is opening your chest. The doctor is “redecorating” your heart…OK, killing tiny parts of your heart. People occasionally die. There can be complications like infections. How long has your doctor been doing ablations? How many a year? I asked my EP where he learned the technique. Turned out that he learned it from the French doctor who invented it. Peer recognition is good. My EP leads the Atrial Fibrillation Center at the big regional hospital where I had the work. Find out if they are involved in research since this suggests they keep up on the latest developments. I saw that my EP was doing research via the U.S. government’s Medline Plus clinical trial website (https://medlineplus.gov/clinicaltrials.html). And if you are reading about the latest research on the Internet, you can see if your doctor is keeping up with the latest. I asked my EC about a study that appeared days before our appointment. He read it and talked about it. He passed my tests.
(I’ve been meaning to write about a recent study which looked at the early mortality rate (<30 days after procedure) from catheter ablation for atrial fibrillation which was 0.46% among more than 60,000 patients treated for A-fib ablation between 2010 and 2015. These real-world rates are higher than those reported in randomized trials. This doesn’t necessarily make ablation a “dangerous” procedure but patients should know that there is a 1 in 200 chance of dying from it.)
Interestingly, and relevant to Mark’s point about choosing an EP who does a lot of ablations per year, mortality rate was higher in low volume hospital (<21 ablations per year). These data support choosing a high volume operator in a high volume hospital.
Once you choose a doctor, the remainder is scheduling and insurance paperwork. My experience is that you should assume at least a day in the hospital and a day to recover.
I arrived early the day of the procedure. After my previous cardioversions I was experienced with the registration and prep process. A few hours later I was on a gurney entering “mission control.” The procedure room was full of large TV’s, reminding me of launching a rocket. It can be a bit intimidating, but I thought of it as a sports bar. Instead of watching games people were watching my heart. It wasn’t a long time in the room before I was told I’d be sleeping soon.
They were right because I “woke up” about four hours later in a recovery room. I immediately saw my heart rate was in the 70’s and steady. That was good. I put on my Apple Watch and started the ECG test. Without waiting for the watch to decide, I could see my beats were rhythmic. YEAH! I saw “normal sinus rhythm” on the watch and celebrated. Later I found out that I had almost four hours of a successful ablation. Apparently, that is a lot of work however the afib, aflutter, was gone.
After the procedure I felt pressure around my heart. Not surprising considering the “redecorating” that was done. It was more of an annoyance than painful. That lasted for a few days. The area around my groin was also sore from the insertion of the ablation instruments. Certainly not unbearable but not fun. A couple of hours after the procedure I asked if I could go for a walk. The staff accompanied me for a walk and saw that I was fine. I asked if I continue walking. After a mile of moderate walking around the hospital (thanks to the Apple Watch’s measurements), my groin felt much better. When my watch showed I walked three miles, I went to bed. The following morning before breakfast, I walked another three miles. After ablation, start walking as soon as you can. It helped me physically and probably more important mentally showing that I was OK.
My groin area was purple for about a week so the worst part of the ablation was I couldn’t wear a Speedo (nor did I want to wear one). It was ugly and a minor nuisance but didn’t affect my activities. Oddly the second day after the procedure I woke up feeling the aftermath of cramps in both of my calves. This was bothersome walking stairs especially. I hadn’t heard of cramps associated with an ablation so it may just have been coincidence. The next day I could walk fine.
Post-Ablation Early Recurrence
My heart was fine after the ablation. I checked it regularly with my Apple Watch and Kardia Mobile EKG. Life was good until 1:55AM a couple of weeks after the ablation. I was sleeping. Without explanation my heart rate jumped from 53 beats per minute to 110 in five minutes. When I woke hours later, I knew my heart was racing. The Kardia Mobile showed I had a “uncategorized” problem. It stayed around 110 beats no matter what I was doing. A few hours later my EP saw my EKG chart and said I needed another cardioversion. He reminded me that he told me the first time we discussed ablation that during the first three or four months I might have more rhythm problems as the heart returns to normal. He was right.
A few days later I had my third cardioversion. My heart immediately went from 110 back to 60/70 beats per minute after the procedure. Yeah! I was beating normally again.
One Month After Ablation
Today is a month after the last cardioversion. My Apple Watch, Kardia Mobile, and body tell me I am fine. The other metric I check regularly is my heart rate while sleeping since it should reflect my heart rate without activity. I’m averaging 54 beats per minute at night which is fine. I can now exercise moderately or intensely. I am celebrating by writing this article.
I continue to take a blood thinner because of my CHADS₂ score. Hopefully my afib adventure is over…but I will not be surprised if it returns.
So far, so good.
Hopefully, Mark will remain free of afib for many years if not a lifetime but given that he is empowered with both a Kardia 6L device and an Apple Watch for monitoring his rhythm I feel confident he will know when and if it returns.
N.B. Here are the charges for the ablation procedure.
Hospital – 86,350
EC/EP – 7,365
Anesthesia – 4,550
Blood test – 120
Misc charge – 22
Mark ended up paying $200 out of pocket.
Mark Goldstein works in the field of cybersecurity in the Washington, DC area and can be contacted at https://www.linkedin.com
Apple Watch and other fitness trackers have the capability to provide us with information on cardiovascular parameters which reflect the activity of the autonomic nervous system (ANS). Measures of the activity of the ANS reflect the balance between the sympathetic nervous system (which activates fight and flight responses) and the parasympathetic nervous system (which activates “rest and digest” activities) and have been shown to be powerful predictors of mortality.
Most of the attention in this areas has been on heart rate variability (HRV) with various wearables trying to promote HRV as a surrogate marker for stress. The OURA ring people for example state without evidence that “high heart rate variability is an indication of especially cardiovascular, but also overall health as well as general fitness.”
Although unimpressed with the HRV data from Apple Watch or the OURA ring I have recently discovered that I can get a more useful parameter of ANS tone from my Apple Watch-Heart Rate Recovery.
What Is Heart Rate Recovery?
Heart Rate Recovery (HRR) is the rate of decline in heart rate after the cessation of exercise. Basically you measure heart rate right when you stop exercising and again a minute later (and/or two minutes later) and subtract one from the other.
Unlike HRV you don’t really need any high tech devices to make this simple but highly reproducible measurement. You can simply measure your pulse the old-fashioned way by putting a finger on your carotid or radial artery and counting the beats.
What happens to the heart rate during exercise has long been considered to be due to the combination of parasympathetic withdrawal and sympathetic activation.
The fall in heart rate immediately after exercise has been shown to be a function of the reactivation of the parasympathetic nervous system. It is accelerated in athletes and blunted in patients with heart failure.
The study examined outcomes in 2428 consecutive adults (mean age 57 years, 63 percent men) without significant prior cardiac disease who were referred to the Cleveland clinic cardiac lab for nuclear stress testing. Patients underwent symptom-limited exercise on a treadmill using a standard or modified Bruce protocol.
Heart rate was recorded at peak exercise and then patients walked upright and were walking at a speed of 1.5 miles per hour at a grade of 2.5 percent when heart rate was checked a minute later.
Median HRR was 17 beats per minute, with a range from the 25th to the 75th percentile of 12 to 23 beats per minute. Abnormally low HRR was selected as <13 beats/min and was found in 639 patients (26 percent).
In univariate analyses, a low value for the recovery of heart rate was strongly predictive of death, conferring a four-fold increased risk. After adjustment for multiple confounding factors including age and exercise capacity, patients with HRR <13 beats/min had a two-fold risk of dying.
This 20 year old study and HRR remain highly relevant. The paper has been cited 1001 times since publication and thus far in 2019 58 papers have referenced it.
In a follow up study this same Cleveland Clinic group looked at nearly 10 thousand patients undergoing treadmill ECG testing and found HRR <13 beats/min doubled the 5 year risk of death. In the figure below mortality jumps markedly as HRR drops below 13 and quite dramatically if <10 beats/min.
Subsequent studies from different investigators confirmed that HRR is associated with mortality, independent of workload and myocardial perfusion defects, treadmill risk score, and even after adjusting for left ventricular function and angiographic severity of coronary disease.
There has been a lack of consistency in these studies in stress protocols, activity post-exercise and optimal duration of heart beat measurement post exercise.
This 2001 JACC paper determined that a 2 minute HRR <22 beats/min provided a better cut-point than one minue HRR <13 beats/min in predicting mortality at 7 years in male veterans. Individuals underwent maximal treadmill followed by lying down and those with an abnormal HRR were 2.6 times more likely to die. The HRR was equivalent to age and exercise capacity for predicting death.
Apple Watch and Heart Rate Recovery
It’s not entirely obvious how to view the heart rate recovery data on your Apple Watch but it is routinely logged if you record an activity and end it precisely at the end of the activity. To see it you must leave the activity app and open the Heart Rate APP.
Scroll to the bottom of the screen and you will see HR data on your most recent activity including the peak HR and one minute recovery heart rate.
Click on that tab and the full and awe-inspiring graph of your recovery heart rate over 3 minutes is revealed. Here is mine which followed a 1.5 mile run at 6-7 MPH. I did not walk at 1.5 MPH on a 2.5% grade in recovery which would be needed if one wanted to more carefully compare a personal HRR to the numbers from the 1999 NEJM study.
The Watch only stores data on your last workout but if you go to the Activity app on your iPhone (something I had never previously done) you will find under the workouts tab a complete listing of all previous workouts.
Click on the workout of interest and all the data from the workout is wondrously revealed including cadence, pace and near the bottom heart rate changes. Swipe the heart rate changes during exercise to the left and the heart rate recovery graph is revealed. This time you will have to do the subtraction for yourself
Heart Rate Recovery-Simple, Powerful And Intuitive Measure of Autonomic Tone
So there you have it. Heart Rate Recovery (unlike HRV) is a simple parameter, easy to understand and measure. It yields information on your vagal/parasympathetic tone and has been proven to be a powerful and independent predictor of your overall mortality.
It makes more sense to pay attention to HRR if one wants a measure of your body’s autonomic tone than HRV.
If your one minute HRR is <13 beats per minute or two minute HRR <22 beats per minute this is a bad prognostic sign. If you have not been diagnosed with significant cardiovascular disease consider seeing a physician for evaluation..
For those who have been sedentary and are deconditioned or overweight, consider an abnormal HRR as a wake-up call to modify your lifestyle and improve your mortality.
For healthy, asymptomatic individuals the HRR can serve as a marker for your overall cardiovascular fitness. Monitor it along with your exercise capacity, peak heart rate and resting heart rate to raise your awareness of how your exercise is influencing your overall autonomic nervous system balance.
One of the joys of writing this blog is the communication it allows me with discerning individuals and patients across the planet. One such reader, Mark Goldstein, discovered he was in atrial fibrillation after purchasing an Apple Watch 4.
He now utilizes both the Kardia Mobile ECG and the Apple Watch to aid in his personal monitoring of his atrial fibrillation and has been actively pursuing a rhythm control strategy under the care of his electrophysiologist.
I asked him to share with my readers his experience which recently culminated in an ablation.
What follows is his description with my editorial comments in green.
December 2018 I bought a crazy, expensive Apple Watch. That watch may have saved my life. I spend much of my days at a treaddesk (a combination desk and treadmill). I was curious to find out how much exercise I was doing. I bought the watch, put it on, and starting walking as I do almost every day. Two hours later the watch had an alarm. It was warning me about something called “atrial fibrillation,” It said, “your heart has shown signs of an irregular rhythm.” What! I never heard of afib before. I quickly learned about it. Heart palpitations, no. Pain/pressure in the chest, no. Sweaty, faint, dizzy, etc., no, no. no. I checked the box for tired but I assumed it was because of the amount of exercise I was doing.
The next day I was fortunate that I had a physical scheduled a year ago. I told my doctor that my “crazy, expensive watch” thinks I have afib. My doctor laughed, telling me about how he had checked and probed every part of my body for the last 20 years (the probing part I remembered well). As the exam was concluding, he was puzzled by the afib warning so he grabbed my wrist to check my pulse. A few seconds later he was asking the nurse to give me an EKG. Darn, the watch was correct (and for me it was correct 99% of the time when I had afib and when I was normal – praise to Apple).
(This is a great example of how atrial fibrillation can be missed by the routine office physical examination. Some patients, especially those with non-rapid heart rates (due to rate slowing meds like beta-blockers or to intrinsically slow conduction of electrical impulses) are minimally symptomatic and their pulses don’t feel that irregular. Because the first symptom of afib can be stroke I am an advocate of screening)
Shortly I got to meet a cardiologist (like Dr. Pearson, they are all nice people). Another EKG, afib confirmed. As we were talking about my symptoms or lack of symptoms, he said that afib was a bit like Eskimo’s describing snow. Each snowflake is unique and each afib patient is unique. I was in persistent afib. Probably had been in this state for two or three years since my heart rate jumped while sleeping, exercising, and at rest.
(Each afib experience is unique but not all cardiologists are nice people. Mark has been fortunate.)
The treatment plan was a cardioversion, an electrical shock to the heart, or as my cardiologist described it “like rebooting a computer.”
As a tech person, I understood that. The risk of not fixing my afib was five times the likelihood of a stroke. The risks were minimal so I chose the cardioversion.
(A common misconception is that ablation or cardioversion eliminates or substantially lowers the risk of stroke in afib. This is not the case. I’ll devote a future post to delve into this issue.)
Cardioversion one lasted four days before my Apple Watch started to detect afib.
(I’ve described in detail how helpful patient utilization of personal ECG monitoring is in letting me know the rhythm status of patients prior to and following cardioversion here.)
The cardiologist next step was cardioversion two along with a drug to help with rhythm control. Number two lasted a month before I saw my heart rate jump again. I thought something was wrong even though my watch was not detecting afib. Another EKG, this time the result was aflutter. The cardioversions were indeed like a reboot of the computer. If you have a virus on your computer, a reboot may be a temporary fix but eventually the virus will return.
(There are many drugs whose purpose is to suppress the recurrence of atrial fibrillation. Mark was prescribed the extended release version of propafenone, a Type IC antiarrhythmic drug (AAD) similar in efficacy and side effects to flecainide. Type IC AADs should only be used in patients with normal left ventricular function (which was demonstrated in Mark by an echo) and without significant coronary artery disease (typically proven by a negative stress test).
To Ablate Or Not To Ablate
Now I got to meet an electrocardiologist. He said my afib would return and recommended an ablation. He said it was unlikely to be a permanent cure but it would help.
The aflutter disappeared after a day or so. I thought my afib was gone too but should I have an ablation? Ablations are relatively safe but since I was afib free why have the procedure?
I purchased the new Kardia Mobile six-lead portable EKG, a miracle of technology. Highly recommended for peace of mind. Just like my watch, I was seeing normal sinus rhythm. So why get an ablation?
A cardiologist had a YouTube video talking about the decision to have an ablation or any medical procedure. How will it affect the quality of your life or the quantity (how long will you live). This was a simple analysis and I like simple. I heard from my cardiologist that the evidence is that an ablation will unlikely extend my life nor will it reduce my lifespan. It was likely to not affect my lifespan. I confirmed this via independent research (be an informed patient, your outcomes will be better). See Dr Pearson’s articles about the CABANA study and the scientific evidence on ablation). So an ablation and quantity of life were neutral.
Importance Of Quality Of Life
Quality of life was more interesting. Could I do the things wanted to do with my life? Did afib affect my day-to-day life? Could I walk up a couple of flights of stairs without breathing hard? Was I getting tired at 10AM? Could I exercise? At the time, the answer was easy. I could do everything I wanted to do. The afib affect was just about zero except for blood thinner drugs which I suspect I will take forever. No ablation.
Then “the day.” I woke and checked my sleep app on my phone. Heart rate at night jumped. Hmm! I went to the gym. My heart rate while walking jumped too. I did 30 seconds of high-intensity exercise and my heart rate monitor said 205 beats per minute. My heart was beating so hard I had to sit for five minutes. I knew something was wrong. Then I climbed a couple of flights of stairs, something that would never bother me. I felt a shortness of breath. I knew my afib was back. I also knew that the quality of my life was now being affected. I could not do things I wanted to do. My watch and Kardia Mobile EKG confirmed what I knew.
I called my electrocardiologist and scheduled an ablation. He was right. Afib would return.
(Mark tells me that he was taken off his propafenone one month after the second cardioversion because “the PA said I no longer needed it since I was in sinus rhythm.” My practice would have been to continue the propafenone as long as well tolerated and effective in suppressing afib recurrence. In my experience, the recurrence of Mark’s afib may not have been a failure of medical therapy. I treat patients similar to Mark by continuing the anti-arrhythmic drug since the minimal risks are lowered by regular monitoring and I regularly see maintenance of SR.”)
(Other antiarrhythmic medications were mentioned to Mark but as they required a 3 day hospital stay he was not interested.)
Stay tuned: Part two Of Mark’s post will be about the ablation procedure which he recently underwent.
The skeptical cardiologist keeps his eyes open for new, potentially improved ways of personal mobile ECG monitoring and when I saw the following comments on an afib forum I was intrigued:
I recently started using a SonoHealth product that I find MUCH MUCH superior to Kardia..
Really? MUCH MUCH superior? The more someone utilizes all caps
to emphasize theirs points the less I tend to believe them. But, as I am on a mission to discover the truth in all things cardiologic I went to the SonoHealth website and encountered this:
The EKGraph would indeed appear to be MUCH MUCH superior to Kardia mobile ECG if the website marketing can be believed.
Like the Kardia the EKGraph offers a personal ECG monitor obtained using the fingertips and syncing to an app on your smartphone.
The EKGraph claims to have 3 lead capability, something it emphasizes in its marketing but it is only capable of displaying one lead at a time and , similar to Kardia one can obtain lead II and precordial ECG leads by putting one electrode on the leg or chest.
Also similar to Kardia, the EKGraph promises “rhythm detection.” As we shall learn, however, rhythm detection by the EKGraph cannot be trusted whereas Kardia has a wealth of published data supporting its accuracy.
Unlike the Kardia, the EKGraph does have a “bright LCD screen” which displays the ECG wave pattern and heart rate along with the heart rhythm diagnosis.
I emailed SonoHealth and they were kind enough to send me one of their ECG devices to demo. After spending some time with it I can say unequivocally that it should not be purchased or utilized by any patient who wants reliable personal mobile ECG monitoring with accurate diagnoses.
A few days later a package arrived containing the EKGraph in an Applesque box which also contiained a USB charging cable. In addition they included a carrying case and a tube of ECG gel.
Working With The SonoHealth APP
To make a recording one puts the metal strip on the left side of the device on hand, arm or leg and the other metal strip on the right side of the device on an opposing limb or the chest.
This very happy model gives you a feel for the size of the device and the method of making a Lead I recording.
It is possible to made a decent single lead ECG tracing with this device and view the tracing on the associated smartphone app. However, the recordings are typically very noisy and full of artifact making it hard to discern the rhythm. The software appears to lack appropriate filtering.
The SonoHealth app is free but getting it registered was a problem. On the company website support area several readers have complained of the same problem over the last few months:
I am having trouble registering on the phone because when I hit the red button to register, I see the email and username fields at the top of the form, but when I click on email, the info fields jump to name, and I can’t scroll up to access those two fields. I then get a notification that those two fields are required to register. Any suggestions?
There is no response to this issue posted 3 months ago from the company.
Syncing with the app via Blutooth is straightforward. Pressing the sync button transfers all new tracings to the app where they can be reviewed.
Tracings can be emailed or printed.
The major problem with the EKGraph is that its ability to diagnose rhythm is very limited. This device has no published data verifying the accuracy of its rhythm diagnoses whereas the Apple Watch 4 and Kardia ECG devices do. It it is not approved by the FDA.
I used the device on my self and despite identical rhythms the EKGraph called one “tachycardia” and the other “bradycardia.”
I tried using the SonoHealth on patients in my office who were in normal sinus rhythm and received wild, seemingly random diagnoses.
Whatever algorithm the device is using to diagnose rhythm is clearly not making allowances for poor quality recordings.
This patient is in NSR but the EKGraph calls it “tachycardia, VPB bigeminy” mistaking the artifact between the normal QRS beats and ventricular ectopic beats.
Multiple Sketchy Companies Utilizing Similar Hardware
I have noted other mobile ECG device with a remarkably similar appearance to the EKGraph. A search on Amazon yields AliveCor’s devices and the SonoHealth Ekgraph . The Amazon comparison page shows 3 additional EKGraph identical-appearing devices seemingly from 3 different sketchy companies all priced at $79.
A consumer asked SonoHealth about the identical external appearance of SonoHealth’s and EMAY’s devices and the company’s response was::
As a small new company making a new design for the outside shell didn’t seem viable. A mold from scratch costs anywhere from $65,000-$85,000. So our manufacturer allowed us to use their current mold to make the EKGraph.
So even though the outside is similar the software side is totally different. We have new and improved software. There’s also our own SonoHealth app that we developed from scratch.
SonoHealth is a USA company that provides excellent customer support.
I would disagree with SonoHealth’s assessment-there is nothing to suggest their software is either new or improved or even accurate.
The app that they developed from scratch is clunky and difficult to use.
Ratings and Online Presence of SonoHealth
SonoHealth posts on its website alleged reviews of EKGraph. They are uniformly positive. It’s hard to find anything that isn’t 5/5 stars. Apparently, all the problems I found with the product are unique to me.
However, these reviews should be taken with a grain of salt. A few weeks after acquiring my SonoHealth EKGraph I received an email from the company offering a gift card if I followed their precise instructions in writing a review:
TERMS: In order to receive the $10 giftcard reward you MUST write both a Companyand a Product review. We will send each reviewer the egiftcard to the email that they provided when leaving the review. (For verification purposes, the email you enter when leaving the review must match the email associated with your order.)
This manipulation of the review process is shady and calls into question the validity of any review on the company website or Amazon.
Let The (Mobile ECG) Buyer Beware
The SonoHealth EKGraph is capable of making a reasonable quality single lead ECG. Presumably all the other devices utilizing the same hardware will work as well.
However, the utility of these devices for consumers and patients lies in the ability of the software algorithms to provide accurate diagnoses of the cardiac rhythm.
Apple Watch 4 and AliveCor’s Kardia mobile ECG do a very good job of sorting out atrial fibrillation from normal rhythm but the SonoHealth EKGraph does a horrible job and should not be relied on for this purpose.
The companies making and selling the EKGraph and similar devices have not done the due diligence Apple and AliveCor have done in making sure their mobile ECG devices are accurate. As far as I can tell this is just an attempt to fool naive patients and consumers by a combination of marketing misinformation and manipulation.
I cannot recommend SonoHealth’s EKGraph or any of the other copycat mobile ECG devices. For a few dollars more consumers can have a proven, reliable mobile ECG device with a solid algorithm for rhythm diagnosis. The monthly subscription fee that AliveCor offers as an option allows permanent storage in the cloud along with the capability to connect via KardiaPro with a physician and is well worth the dollars spent.
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.
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.
As I described here, the Kardia Band (KB) is an FDA-approved Apple Watch accessory available to the general public without a prescription which records a high quality single-lead ECG.
I’ve been using mine now for a while and can confirm the ease and accuracy of the ECG recordings it makes. I find recordings made with my Apple Watch/Kardia Band are reliably high quality with minimal artifact (unless I’m running on a treadmill.)
Once the 30 second recording is completed, the Kardia app on the Apple Watch takes about 5 seconds to process the information using an AI algorithm and then makes a determination of normal sinus rhythm (NSR), atrial fibrillation or unclassified.
In the JACC study, investigators from the Cleveland Clinic studied 100 consecutive patients presenting for cardioversion from AF with recordings made before and after the procedure. KB interpretations were compared to 12 lead ECGS read by electrophysiologists.
KB interpretations identified AF with 93% sensitivity and 84% specificity. Of the total 169 recordings, 34% were unclassified due to short recordings, low-amplitude p waves, and baseline artifacts.
The authors concluded that the KB algorithm for AF detection, when it is supported by a physician review can reliably differentiate AF from NSR.
(Of note the lead author on this study is on the advisory board of Alivecor the maker of the KB and AliveCor (AliveCor, Mountain View, CA) provided the Kardia Band monitors which were connected to an Apple Watch and paired via Bluetooth to a smartphone device for utilization in the study. AliveCor was not involved in the design, implementation, data analysis, or manuscript preparation of the study.)
My Updated Kardia Experience
I have found the standard Kardia device to be immensely helpful in the management of my afib patients before and after cardioversions (see my prior description here). The paper mentions that 8% of these pre-cardioversion patients showed up for the procedure in normal sinus rhythm, noting that
For each of these patients, the automated KB algorithm did not erroneously identify AF, and the physician interpretation of the KB recording correctly confirmed SR in each case.
Needless to say, it is better to find out a cardioversion is not needed before the patient shows up for the procedure. I would estimate this happens about 5-10% of the time in my practice.
The Kardia device or the KB is also really helpful post cardioversion. If the patient makes daily recordings (which I can review on Kardia Pro online) h/she and I know exactly how long sinus rhythm persisted before reverting back to AF.
This is important information which impacts future management decisions.
Kardia Band Versus Standard Kardia Device
None of my patients have purchased the Kardia Band most likely due to the cost and the fact that they don’t have an Apple Watch. If you have an Apple Watch and want to monitor your heart rhythm I think the KB is a good choice. Otherwise, the original AliveCor mobile ECG device continues to do a fantastic job (in conjunction with Kardia Pro, see here).
The combination of Kardia and Kardia Pro has substantially reduced my use of expensive and annoying long term monitors in my AF population.
In my next update on the KB I will share a reader’s real world description of the pros and cons of the KB (with Smart Rhythm monitoring) in a patient post cardioversion for AF.