Tag Archives: Apple Watch

Heart Rate Recovery: A Simple and Powerful Predictor of Mortality Now Available On Your Apple Watch

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.

Heart Rate Recovery As A Predictor Of Mortality

A 1999 study published in the New England Journal of Medicine found that abnormally low HRR doubled the risk of dying over 6 years.

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.

m_joc00680f2

 

 

 

 

 

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.

My data shows a peak HR of 121 BPM which dropped to 90 BPM at one minute (121-90=31). Two minute recovery is 121-78 or 43 bpm. Both values are WNL

 

IMG_2A2C306430A7-1

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.

Autonomously Yours,

-ACP

Atrial Fibrillation Detection, Personal ECG Monitoring and Ablation: A Patient’s Story

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).

Recording from Mark’s Apple Watch 4 showing atrial fibrillation with controlled ventricular response. Heart rate is only 82 beats per minute. The AW algorithm correction identifies atrial fibrillation.

(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.”

(See my post on cardioversion here.)

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.

Skeptically Yours,

-ACP

Mark Goldstein works in the field of cybersecurity in the WashingtonDC area and can be contacted at https://www.linkedin.com/in/markhgoldstein/

A Review Of SonoHealth’s EKGraph Portable ECG Monitor: Comparison To Apple Watch ECG And AliveCor’s Kardia ECG

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.

Rhythm Detection

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 Company and 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.

Skeptically Yours,

-ACP

Can The Apple Watch Or Kardia ECG Monitor Detect Heart Attacks?

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.

Similarly, although the AliveCor Kardia ECG monitor is superb at diagnosing rhythm abnormalities it is not capable of detecting an MI

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

The article begins
Scott Killian never imagined his Apple Watch might save his life, but that’s exactly what happened a few weeks ago when he had a heart attack in the middle of the night. Killian recently shared his personal experience with 9to5Mac, and the details of his story are absolutely amazing.
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:
 
 
 
 
 
 
 
The Fox News article entitled “Could The Apple Watch Series 4 save you from a heart attack” quotes a non-physician who suggests that AW can detect early signs of a heart attack:
 

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!

Skeptically Yours,

-ACP

Apple Heart Study: Despite The Ballyhoo, No Benefits Demonstrated, Harms Not Measured

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:

  1. Participants enrolled by submitting  information using the iPhone Heart Study app and none of their isubmitted nformation was verified.
  2. 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)
  3. Only 945 of the 2161 who received a pulse notification participated in the first study visit.
  4. 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.”

  5. 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.)
  6. After all these exclusions only 658 ECG monitor patches were shipped to the participants of which only 450 were returned and analyzed.
  7. 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.
  8. Of the 450 ECG patches analyzed only 34% were classified as having afib. Only 25% of this afib lasted longer than 24 hours.
  9. 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.

Tachogramophobically Yours,

-ACP

Apple Watch Fails To Notify Patient Of 3 Hour Episode Of Rapid Atrial Fibrillation

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.

From this link on their website Apple says:

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.

Skeptically Yours,

-ACP

Update On The Kardia Band Apple Watch Accessory: Accuracy In Atrial Fibrillation Pre and Post Cardioversion

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.

 

 

The New Study

A study published in the June JACC examined the accuracy of  Alivecor’s Kardia Band in detecting atrial fibrillation (AF.)

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.

Skeptically Yours

-ACP

Review of Kardia Band Mobile ECG for Apple Watch

The skeptical cardiologist has been evaluating the Kardia Band from AliveCor which allows one to record single lead medical grade ECGS on your Apple Watch. What follows is my initial experience with setting up the device and using it to make recordings.

After ordering my Kardia Band for Apple Watch on 11/30  from AliveCor the device appeared on my door step 2 days later on a Saturday giving me most of a Sunday to evaluate it.

What’s In The Box

Inside the box I found one small and one large black rubber wrist watch band

The larger one had had a small squarish silver metallic sensor and the smaller one had a space to insert a sensor. It turns out my wrist required the smaller band and it was very easy to pop out the sensor and pop it into the smaller band.

After replacing my current band with the Kardia band (requires pushing the button just below the band and sliding the old band out then sliding the new one in) I was ready to go.

The Eternal  fiancée did not complain about the appearance of the band so I’m taking that to mean it passes the sufficiently stylish test. She did inquire as to different colors but it appears AliveCor only has one style and one color to choose from right now.

I have had problems with rashes developing with Apple’s rubbery band and switched to a different one but thus far the Kardia band is not causing wrist irritation.

Set UP

I didn’t encounter any directions in the box or online so I clicked on the Kardia app on the watch and the following distressing message appeared.

Prior to 11/30 Kardia Band only worked in certain countries in Europe so I suspected my AliveCor app needed to be updated.

I redownloaded the Kardia app from the Apple App Store , deleted it off my Watch and reinstalled it.

I was thrilled when the app opened up and gave me the following message

However, I was a little puzzled as I was not aware that setting up Smart Rhythm was a requirement to utilize the ECG recording aspect of Kardia Band. Since I have been granted a grandfathered Premium membership by AliveCor I knew that I would have access to Smart Rhythm and went through the process of entering my name and email into the Kardia app to get this started.

Alas, when the Watch Kardia app was accessed after this I continued to get the same screen. Clicking on “need help” revealed the following message:

Bluetooth was clearly on and several attempts to restart both the watch and the iPhone app did not advance the situation.

I sent out pleas for assistance to AliveCor.

At this point the Eternal Fiancee had awoken and we went to Sardella for a delightful brunch . I had this marvelous item:

Eggs Benedict Raviolo, Mortadella, Bread Ricotta, Egg Yolk, Brown Butter Hollandaise, Potatoes 15.
 Later on that day I returned to my Kardia Band iPhone and deinstalled, reinstalled , reloaded and restarted everything.
The First Recording
At this point it worked and I was able to obtain my first recording by pushing the record ECG button and holding my thumb on the sensor for 30 seconds.
I’ve made lots of recordings since then and they are good quality and have accurately recognized that I am in normal sinus rhythm.
The Smart Rhythm component has also been working. Here is a screen shot of today’s graph.
You’l notice that the Smart Rhythm AI gave me a warning sometime in the morning (which I missed) as it felt my rhythm was abnormal. I missed making the recording but am certain that I was not in afib.
Comparison of the Kardia Band recording (on the right) versus the separate Kardia device recording (on left)  shows that they are very similar in terms of the voltage or height of the p waves, QRS complexes and T waves. 
I felt a palpitation earlier and was able to quickly activate the Kardia Watch app and make a recording which revealed a PVC.
 In summary, after some difficulty getting the app to work I am very pleased with the ease of recording, the quality of the recording and the overall performance of Kardia Band. The difficulties I encountered might reflect an early adoption issue which may already be resolved. Please give me feedback on how the device set up worked for you.
I’ll be testing this out on patients with atrial fibrillation and report on how it works in various situations in future posts.
After more experience with the Smart Rhythm monitoring system which I think could be a fantastic breakthrough in personal health monitoring I’ll give a detailed analysis of that feature.
Everwatchingly Yours,
-ACP

AliveCor’s Kardia Band Is Now Available: Mobile ECG On Your Apple Watch

AliveCor has finally gotten approval from the FDA to release its Kardia Band in the United States.

The skeptical cardiologist is quite excited to get his hands (or wrist) on one and just gave AliveCor $199 to get it.

The device incorporates a mobile ECG sensor into a wrist band that works with either 42 or 38 mm Apple watches. I’ve written extensively about AliveCor’s previous mobile ECG product (here and here) which does a good job of recording a single lead ECG rhythm strip and identifying atrial fibrillation versus normal rhythm,

Hopefully, the Kardia Band will work as well as the earlier device in accurately detecting atrial fibrillation.

According to this brief video to make a recording you tap the watch screen then put your thumb on the sensor on the band.

The app can monitor your heart rate constantly and alerts you  to make a recording if it thinks you have an abnormal rhythm.

I was alerted to the release of Kardia by Larry Husten’s excellent Cardio Brief blog and in his post he indicates that the alert service , termed Smart Rhythm,  requires a subscription of $99 per year.:

AliveCor simultaneously announced the introduction of SmartRhythm, a program for the Apple Watch that monitors the watch’s heart rate and activity sensors and provides real-time alerts to users to capture an ECG with the Kardia Band. The program, according to an AliveCor spokesperson, “leverages sophisticated artificial intelligence to detect when a user’s heart rate and physical activity are out of sync, and prompts users to take an EKG in case it’s signaling possible abnormalities like AFib.”

The Kardia Band will sell for $199. This includes the ability to record unlimited ECGs and to email the readings to anyone. The SmartRhythm program will be part of the company’s KardiaGuard membership, which costs $99 a year. KardiaGuard stores ECG recordings in the cloud and provides monthly summary reports on ECGs and other readings taken.

AliveCor tells me my Kardia Band will be shipped in 1-2 days and I hope to be able to give my evaluation of it before Christmas.

Please note that I paid for the device myself in order to avoid any bias that could be introduced by receiving largesse from AliveCor.

Proarrhythmically Yours

-ACP

N.B. Larry Husten’s article includes some perspective and warnings from two cardiologist and can be read here.

Another article on the Kardia Band release suggests that the Smart Rhythm program at $99/ year is a requirement.

Perhaps, AliveCor’s David Albert can weigh in on whether the annual subscription is a requirement for making recordings or just allows the continuous monitoring aspect.

Six Things a Cardiologist Loves About Apple Watch Series 1 – None of Which Involve Health

The skeptical cardiologist stopped wearing his initial wearable piece of technology (a Garmin device that constantly prompted him to move, described here), within 6 months of purchasing it; it just wasn’t worth the effort of charging and putting on the the wrist.

I am not alone in finding FitBit type devices not worth wearing after awhile. ConscienHealth points out that sales and stock price of FitBit are down significantly.  Part of this is competition, part saturation of the market, but part must be due to individuals going through a process similar to mine.

The great promise that wearable fitness/sleep/activity tracking devices would make us healthier has not been fulfilled.

A recent study showed that among obese young adults, the addition of a wearable technology device to a standard behavioral intervention resulted in less weight loss over 24 months.

Taking the Apple Watch Plunge

However, knowing I was a fan of all things Apple, the eternal fiancee  bought me a Series 1 Apple Watch, which I have come to love. This love has little to do with how the device tracks my steps or my sleep or my pulse or my movement.

Let me count the ways I do love my Apple Watch…

  1. I can answer my phone without touching my phone or

    If I see a call is coming in from Hackert, my home security company, I have to take it no matter what I’m doing. Here I’m having a conversation about what set off my home alarm just using the Apple Watch

    having it near me or even knowing where my phone is.

    Since I’m constantly misplacing the damn thing, this is a surprisingly helpful feature. There is also the really cool aspect of walking around and having a telephone conversation  using my watch.

During a busy day of seeing patients in the office I typically will receive multiple calls from the ER or other doctors I have to talk to immediately.  Now, I can rapidly screen my calls with a tilt of my wrist and excuse myself to take the call. If I’ve been trying to get ahold of Dr. X to discuss a mutual patient, and he calls while I’m doing a transesophageal echocardiogram, I can have someone touch my watch instead of reaching into my pants for my iPhone, or searching in my office for it, or missing the call altogether.

 I’m missing much less important calls these days.

And although previously I would take calls while driving, the watch makes this process much simpler and therefore much safer.

2. Receiving and responding to text messages does not require accessing my iPhone.

Responding in detail to texts is as simple as touching the microphone icon on the Watch, speaking, then touching SEND. The translator works pretty well.

This doesn’t seem like that big of a deal, but again, the ability to rapidly scan incoming texts with just a tilt of the wrist greatly facilitates expeditious screening and processing.

The Apple Watch allows response via either audio recording (translated seamlessly and quickly to text) or pre-set standard responses or emojis.

 

3. “Hey Siri” function simplifies and makes hands-free and iPhone-free many useful tasks. For example:

  • To set a timer for my (heart-healthy) boiled eggs, I say “Hey Siri, set timer for 11 minutes.” Normally in this situation I avoid setting the timer because I’m too busy to grab my phone, open it, and find the timer app (I know I could use Siri on my phone, but that requires more effort).
  • If I suddenly remember I need to call someone while driving, the “Hey Siri” function allows making the call without taking my hands off the steering wheel.
  • If a brilliant idea for a blog post occurs to me while driving or walking through the hospital corridors, “Hey Siri” can take a note with ease.

4. Checking the time is a lot easier (I know, all watches do this, but I’ve haven’t worn a watch for about 20 years).

The lower left icon triggers the pinging of iPhone. Watch and iPhone must be “Connected” via either bluetooth and proximity or via being on the same WIFI network.

5. If I misplace my iPhone (this happens roughly once per hour when I am at home), I can “ping” it by pushing a button on my Apple Watch: follow the ping and “voila!” I have found my iPhone. Most of the time it is lying under a piece of paper or article of clothing within a few feet of where I’m working, but sometimes it is in an obscure corner for obscure reasons.

Here’s a true story which illustrates my tremendous absent-mindeness and the value of the “ping.”

I haven’t figured out how the Apple Watch knows this but when I’m getting ready to drive to work in the morning it automatically shows me something like this, advising me on the best route to take. Likewise, when I’m getting ready to leave work, it alerts me to best route home. It’s somewhat creepy. Is it keeping a log of my driving patterns?

I left my office Friday evening and after stepping outside I realized I did not have my iPhone in its usual location, the left front pocket of my pants. I searched the pockets in my pants and in the jacket I was wearing to no avail. I began heading back to my office believing that I had left it on my desk but then realized that I might have put it in my satchel. Not in my satchel. A bright idea then occurred to me: ping the iPhone to see if it was in the satchel, but hidden.

Sure enough I heard the iPhone ping. But it was not in the satchel; it was (for obscure reasons) in my shirt pocket (a place that apparently makes it undetectable to me).

6. Information on local weather is immediately available. I have configured my watch “dial” to show me the local temperature. Right now with a flick of my wrist I can see that it’s 17 degrees outside and I’m going to have to dress warmly. I’ve also configured my watch dial to tell me when sunrise/sunset is and what my heart rate is.

These last two things, although immensely interesting, are not that helpful.

Oh, excuse me, my watch timer is telling me my eggs are done.

Pingophilically Yours,

-ACP

P.S. I’m still in the process of evaluating the work-out/sleep/move/mindfulness features of Apple Watch and hope to write about it in the near future.

Feel free to share the things you love or hate about your Apple Watch below.