Tag Archives: Apple Watch ECG

Atrial Fibrillation In The Time of Coronavirus: A Call For More Personal Remote ECG Monitoring

What is the best strategy for doctors and patients dealing with atrial fibrillation during the COVID-19 pandemic?

Clearly, at this time everyone needs to minimize visits to the doctor’s office, emergency room, urgent care center or hospital. But patients with paroxysmal atrial fibrillation by definition will have periodic spells during which their heart goes out of rhythm and many of these will occur during this period when we want to minimize contact with individuals outside the home.

In my practice, we are able to manage the majority of these episodes remotely by using a combination of personal ECG monitoring, online cloud ECG review capability, and home adjustment of medications.

Given the presence of coronavirus in the community and the potential for overload of acute care medical resources, outpatient/home management of atrial fibrillation is more important than ever.

I have described in detail in previous posts how we utilize Alivecor’s Kardia device in conjunction with the cloud-based KardiaPro subscription service to manage our afib patients remotely.  (See here and here.) The Apple Watch ECG can also be utilized for this purpose but is more expensive than Kardia and has no online review service.

With this approach we are able to minimize ER visits and hospitalizations. In addition, use of long-term monitors (which also requires a visit to an outpatient center for hook-up) has been greatly reduced.

Given heightened anxiety during the pandemic we are also seeing many patients experiencing palpitations, which are not due to their atrial fibrillation. These can be due to benign premature ventricular contractions or premature atrial contractions.

If an afib patient calls with symptoms of palpitations or rapid heart beat and they have a Kardia device or Apple Watch ECG we can review the recorded ECG, and can quickly make a determination of the cause and best treatment. If they don’t have one of these devices we have no idea what the cause is or the best treatment.

General Advice For Afib Patients 

Obviously, it would be great if patients don’t have episodes of afib during the pandemic.

Paying attention to the eight lifestyle factors which influence afib occurrence I’ve recently posted on is even more important during this stressful period. In particular, afib patients should be limiting the inclination to consume more alcohol and utilizing healthier ways to reduce stress.

Regular exercise has demonstrated benefits in reducing afib episodes and also reduces stress. Gyms are closed or closing, but with spring arriving, outside exercise is always possible. Even if you don’t have exercise equipment in your home there are many exercises you can do inside that provide cardio, strength, and flexibility training. Consider bodyweight exercises, jumping rope, hoping on to a small chair, or go find your old Richard Simmons exercise VHS tape. My wife and I have been enjoying the Seven app lately which takes us through a variety of exercises without the need for equipment. There are tens of thousands of exercise videos on YouTube.

Some afibbers find that meditation or relaxation apps or yoga helps with stress control.

Finally, make sure you have plenty of your prescription medications on hand and that you take them as prescribed without fail. Many pharmacies have home-delivery available for prescriptions.

Regarding medications, please note that good blood pressure control also reduces afib recurrence. Do not stop ACE inhibitors or ARBs as I discussed here.

A Call For More Self Monitoring

Given the importance of staying home right now, afib patients who do not have a method for self monitoring their heart rhythms should consider acquiring a Kardia device or Apple Watch.

Antifibrillatorily Yours,

-ACP

N.B. As I’ve mentioned multiple times I have no connections, financial or otherwise to Apple or Alivecor.

KardiaMobile, the original single lead personal ECG is selling for $84 right now. It’s available also on Amazon.

In my opinion, there is no compelling reason to prefer the Kardia6l, which costs $149 over the single lead KardiaMobile.

Both of these devices work with a Google or iPhone app which is free. To store recorded ECGs on Alivecor’s cloud service requires a subscription fee.

When I enroll my patients into KardiaPro I send them an email invitation which allows them to purchase the KardiaMobile plus have one year of cloud storage and connection to my KardiaPro dashboard for $120. Thereafter the one year KardiaPro service is $60/year.

Apple Watch 5 starts at $399. ECGS are stored in the iPhone app. No cloud storage. ECGs can be emailed as PDF.

Patients with Apple 4 Watches or later can send a PDF of their ECG via email or fax to their cardiologist (https://support.apple.com/en-us/HT208955). Check with your cardiologist if they can view a PDF.

NOTE: Apple has closed all of their retail stores outside of Greater China until March 27. Online stores are open at www.apple.com, or you can download the Apple Store app on the App Store so you can still buy an Apple Watch or an iPhone too.

Cheaper personal ECG devices are available. I’ve reviewed several of these and don’t recommend them. (See here and here.)

Thanks to Mark Goldstein  and Dan Field for review/editing of this post.

New Study Confirms Poor Apple Watch ECG App Sensitivity For Atrial Fibrillation

Although Apple, based on its internal research, claims that the Apple Watch (AW) ECG has a 98% sensitivity and a 99% specificity for detection of atrial fibrillation, doubts have been raised about its accuracy in the real world.

I have recently reported on Apple Watch’s inability to diagnose atrial fibrillation  (AF) when the heart rate is >120 beats per minute. This inherent limitation means AW has a built-in reduced sensitivity (which was not present in the testing group.)

In a Research Letter published online Feb. 24th in Circulation, Dr. Marc Gillinov, reports on the accuracy of Apple Watch in a population of patients who were post cardiac surgery  and therefore on cardiac telemetry with a high risk of going in and out of AF.

Rhythm assessments using the Apple Watch ECG were performed 3 times per day over 2 days on 50 patients. Comparison was made between the watch reading (Sinus rhythm, AF, or inconclusive) and an expert human interpretation of the PDF from the watch and simultaneously obtained telemetry rhythm strip.

The results were disappointing for the AW.

The AW4 notification correctly identified AF in 34 of 90 instances, yielding a sensitivity of 41%. Of 25 patients with at least 1 episode of AF, AF was identified in 19. Among patients in SR, none was designated as AF (ie, no false positives); however, rhythm was deemed inconclusive in 31% of patients, and there was no additional attempt to assess rhythm. Overall agreement between AW4 notification and telemetry was 61% (κ statistic = 0.33 [95% CI, 0.24–0.41]).

Screen Shot 2020-02-28 at 3.17.12 PM

This confirms my prediction that AW would identify less than half of AF cases.

I have to believe that the 29 cases diagnosed as “inconclusive” were due to the AW AF inherent blinding limitation related to rapid heart rate. If we presume these would all have been correctly identified as AF (if the AW had not been hamstrung) then the sensitivity increases to 70%.

The authors of this article don’t seem to understand the difference between unreadable (meaning too much artifact to make a diagnosis) versus inconclusive (which Apple only uses when the AF is > 120 BPM.) They conclude by saying:

The unreadable (ie, inconclusive) rate reported in that study was 6% compared with 31% in this pilot study.

They have muddled together unreadable and inconclusive.

I do strongly agree with their final conclusions

Variations in sensitivity between these 2 studies suggest the need for further validation before this technology is adopted by the public for AF detection. Physicians should exercise caution before undertaking action based on electrocardiographic diagnoses generated by this wrist-worn monitor.

Indeed, any diagnosis from the Apple Watch itself should be confirmed by a cardiologist who is an expert at interpreting these single-lead ECG recordings.

Conclusively Yours,

-ACP

Apple Watch ECG Cannot Diagnose Atrial Fibrillation Faster Than 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.

CL-120-AFIB-AW4.png

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.

CL-150-AFIB-AW4.png

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.

Skeptically Yours,

-ACP

An In-depth, Objective Comparison of Mobile ECG Devices: Emay versus Kardia

The skeptical cardiologist has been a huge advocate of personal mobile ECG monitoring to empower patient’s in understanding/monitoring their heart rhythm.

The deserved leaders in this field are the Apple Watch (4 and later) and Alivecor’s Kardia device which comes in single-lead and six-lead flavors.

Both Apple and AliveCor have gotten FDA approval for their mobile ECG device and have a body of published studies supporting their accuracy.

In contrast, there are a number of “copy-cat” mobile ECG devices which have been feeding on the success of Apple Watch and Kardia but do not have the bona fides the two leaders have.

I reviewed the SonoHealth ECG here and found it sorely lacking in comparison to Kardia in terms of accuracy of diagnosis and quality of recordings, the two most important aspects of a personal ECG monitor.

Dan Field, a physician  and reader of my blog, has been evaluating a device similar to the SonoHealth ECG made by Emay.

He has provided a point by point comparison of the two  devices in the chart below

Emay versus Kardia

His summary:

“The Kardia6L was clearly superior in almost every way except for price and even that was within the margin of error. ”

It should be noted that the single lead Kardia mobile ECG is actually cheaper than the Emay and retails for $99.

Let The (Mobile ECG) Buyer Beware

I ended my post reviewing SonoHealth’s ECG with a warning which applies equally to the Emay device:

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

 

A Guide To Using Apple Watch and Kardia ECG devices-What They Can and Can’t Do

Many patients (and perhaps physicians) are confused as to how best to utilize personal ECG devices. I received this question illustrating such confusion from a reader recently:

I first came across your website a year ago during persistent angina attacks, and returning now due to increasing episodes of symptoms akin to Afib. I bought a Kardia 2 yrs ago for the angina episodes, and looking to buy the Apple Series 4 for the Afib, as I want to try a wearable for more constant monitoring. What I would greatly appreciate if you had a basic guide for both the Kardia & Apple devices, specifically when and how to best employ them for unstable angina and detecting undiagnosed Afib. As in, what can I as a patient provide to you as a doctor for diagnosis in advance of a formal visit. I’m a US Iraq vet medically retired in the UK, and most of my concerns get dismissed out of hand as “anxiety”, not sure why they thought a stent would cure my anxiety though  

Personal, Wearable ECG Devices Won’t Diagnose Angina (or Heart Attacks)

First. please understand that none of these devices have any significant role in the management of angina. Angina, which is chest/arm/jaw discomfort due to a poor blood supply to the heart muscle cannot be reliably diagnosed by the single lead ECG recording provided by the Apple Watch, the Kardia Band or the Kardia mobile ECG device. Even a medical-grade 12 lead ECG doesn’t reliably diagnose angina and we rely on a constellation of factors from the patient’s history to advanced testing to determine how best to manage and diagnose angina.

Second, as you are having episodes “akin to Afib”, all of these devices can be helpful in determining what your cardiac rhythm is at the time of the episodes if they last long enough for you to make an ECG recording.

The single lead ECG recording you can make from the Apple Watch, the Kardia Band and from the Kardia mobile device can very reliably tell us what the cardiac rhythm was when you were feeling symptoms.

The algorithms of these devices do a good job of determining if the rhythm Is atrial fibrillation. Also, if the rhythm is totally normal they are good at determining normality.

However, sometimes extra or premature beats confuse the algorithms resulting in an unclassified tracing and (rarely) an inaccurate declaration of afib

These tracings can be reviewed by a competent cardiologist to sort out what the rhythm really is.

In all of these cases, having an actual recording of the cardiac rhythm at the time of symptoms is immensely helpful to your doctor or cardiologist in determining what is causing your problems.

My recommendation, therefore, would be to make several recordings at the time of your symptoms. Print them out and carefully label the print-out with exactly what you were feeling when it was recorded and present these to the doctor who will be reviewing your case.

As I’ve mentioned in previous posts (see here), my patients’ use of Kardia with the KardiaPro online service has in many cases taken the place of expensive and inconvenient long term monitoring devices.

Case Example-Diagnosing Rare And Brief Attacks Of Atrial Fibrillation

I recently saw a patient who I think perfectly demonstrates how useful these devices can be for clarifying what is causing intermittent episodes of palpitations-irregular, pounding, or racing heart beats.

She was lying on a sofa one day when she suddenly noted her heart “pumping fast” and with irregularity. The symptoms last for about an hour. She had noticed this occurred about once a year occurring out of the blue.

Her PCP ordered a long term monitor, a stress test and an echocardiogram.

The monitor showed some brief episodes of what I would term atrial tachycardia but not atrial fibrillation but the patient did not experience one of her once per year hour long episodes of racing heart during the recording. Thus, we had not yet solved the mystery of the prolonged bouts of racing heart.

She was referred to me for evaluation and I recommended she purchase an Alivecor device and sign up for the KardiaPro service which allows me to view all of her recordings online. The combination of the device plus one year of the KardiaPro service costs $120.

She purchased the device and made some occasional recordings when she felt fine and we documented that these were identified as normal by Kardia. For months nothing else happened.

Then one day in April she had her typical prolonged symptom of a racing heart and she made the recording below (She was actually away from home but had the Kardia device with her.)

When she called the office I logged into my KardiaPro account and pulled up her recordings and lo and behold the Kardia device was correct and she was in atrial fibrillation at a rate of 113 BPM.

With the puzzle of her palpitations solved we could now address proper treatment.

Continuous Monitoring for Abnormal Rhythms

Finally, let’s discuss the wearables ability to serve as a monitor and alert a patient when they are in an abnormal rhythm but free of any symptoms.

My reader’s intent was to acquire a device for “constant monitoring”:

I’m looking to buy the Apple Series 4 for the Afib, as I want to try a wearable for more constant monitoring.

This capability is theoretically available with Apple Watch 4’s ECG and with the Kardia Band (using SmartRhythm) which works with Apple Watch Series 1-3.

However, I have not been impressed with Apple Watch’s accuracy in this area (see here and here) and would not at this point rely solely on any device to reliably alert patients to silent or asymptomatic atrial fibrillation.

In theory, all wearables that track heart rate and alert the wearer if the resting heart rates goes above 100 BPM have the capability of detecting atrial fibrillation. If you receive an alert of high HR from a non ECG-capable wearable you can then record an ECG with the Kardia mobile ECG to see if it really is atrial fibrillation.

At 99$, the Kardia is the most cost-effective way of confirming atrial fibrillation for consumers.

I hope this post adds some clarity to the often confusing field of personal and wearable ECG devices.

Electroanatomically Yours,

-ACP

Putting The Apple Watch 4 ECG To The Test In Atrial Fibrillation: An Informal Comparison To Kardia

My first patient this morning, a delightful tech-savvy septagenarian with persistent atrial fibrillation told me she had been monitoring her rhythm for the last few days using her Apple Watch 4’s built in ECG device.

Previously she had been using what I consider the Gold Standard for personal ECG monitoring- AliveCor’s Kardia Mobile ECG   and I monitored her recordings through our Kardia Pro connection.

I had been eagerly awaiting Apple’s roll out since I purchased the AW4 in September (see here) and between patients this morning I down-loaded and installed the required iPhone and Watch upgrades and began making AW4 recordings.

Through the day I tried the AW4 and the Kardia on patients in my office.

Apple Watch 4 ECG Is Easy and Straightforward

The AW4 ECG recording process is very easy and straightforward. Upon opening the watch app you are prompted to open the health app on your iPhone to allow connection to the Watch ECG information. After this, to initiate a recording simply open the Watch ECG app and hold your finger on the crown.

Immediately a red ECG tracing begins along with a 30 second countdown.

Helpful advice to pass the time appears below the timer:

“Try Not to move your arms.”

and

“Apple Watch never checks for heart attacks.”

When finished you will see what I and my patient (who mostly stays in sinus rhythm with the aid of flecainide) saw-a declaration of normality:

Later in the day I had a few patients with permanent  atrial fibrillation put on my watch.

This seventy-something farmer from Bowling Green, Missouri was easily able to make a very good ECG recording with minimal instruction

The AW4 nailed the diagnosis as atrial fibrillation.

We also recorded a Kardia device ECG on him and with a little more instruction the device also diagnosed atrial fibrillation

After you’ve made an AW4 recording you can view the PDF of the ECG in the Health app on your iPhone where all of your ECGs are stored. The PDF can be exported to email (to your doctor) or other apps.

ECG of the Bowling Green farmer. I am not in afib.

Apple Watch Often “Inconclusive”

The AW4 could not diagnose another patient with permanent atrial fibrillation and judged the recording “inconclusive”

The Kardia device and algorithm despite a fairly noisy tracing was able to correctly diagnose atrial fibrillation in this same patient.

I put the AW4 on Sandy, our outstanding echo tech at Winghaven who is known to have a left bundle branch block but remains in normal rhythm and obtained this inconclusive report .

Kardia, on the other hand got the diagnosis correctly:

One Bizarre Tracing by the AW4

In another patient , an 87 year old lady with a totally normal recording by the Kardia device, the AW4 yielded a bizarre tracing which resembled ventricular tachycardia:

Despite adjustments to her finger position and watch position, I could not obtain a reasonble tracing with the AW4.

The Kardia tracing is fine, no artifact whatsoever.

What can we conclude after today’s adventures with the Apple Watch ECG?

This is an amazingly easy, convenient and straightforward method for recording a single channel ECG.

I love the idea that I can record an ECG whereverI am with minimal fuss. Since I wear my AW4 almost all the time I don’t have to think about bringing a device with me (although for a while I had the Kardia attached to iPhone case that ultimately became cumbersome.)

Based on my limited sample size today, however, the AW4 has a high rate of being uncertain about diagnoses. Only 2/3 cases of permanent atrial fibrillation were identified (compared to 3/3 for the Kardia) and only 4/6 cases of sinus rhythm were identified.

If those numbers hold up with larger numbers, the AW4 is inferior to the Kardia ECG device.

I’d rather see the AW4 declare inconclusive than to declare atrial fibrillation when it’s not present but this lack of certainty detracts from its value.

What caused the bizarre artifact and inconclusive AW4 tracing in my patient is unclear. If anybody has an answer, let me know.

We definitely need more data and more studies on the overall sensitivity and specificity of the AW4 and hopefully these will be rapidly forthcoming.

For most of my patients the advantages of the AW4 (assuming they don’t already have one) will be outweighed by its much greater cost and we will continue to primarily utilize the Kardia device which will also allow me to view all of their recordings instantaneously in the cloud.

Conclusively Yours,

-ACP

Note. The original version of this post had the wrong ECG tracing for the first “inconclusive” AW4 recording of a patient with permanent atrial fibrillation. H/t to discerning reader Vignesh for pointing this out months after the initial posting.