Sometimes AliveCor’s Mobile ECG device yields unclassified interpretations of recordings. Understandably if you want to know whether your rhythm is normal or atrial fibrillation, the unclassified classification can be very frustrating.
There are various caues of an unclassified tracing with different solutions. Some unclassified recordings are due to a heart rate over 100 BPM or under 50 BPM and cannot be fixed. Similarly, some patients with ectopic beats like PVCS may consistently generate unclassified interpretations (see my discussion here).
Artifacts induced by poor recording techniques are common as a cause and almost always can be fixed.
These can be reduced by minimizing motion, extraneous noise, and maximizing contact with the electrodes. Follow all the steps AliveCor lists here.
For me, the following step is crucial
If your fingers are dry, try moistening them with antibacterial wipes or a bit of lotion
And be aware the device needs to be near the microphone of your iPad or smartphone.
Low Voltage As Cause of Unclassified Kardia Recordings
Another cause of unclassified interpretations is a low voltage recording (which I initially discussed here.).
At the recent ACC meeting I asked Alivecor inventor and CEO David Albert if he had any solutions to offer for those who obtain unclassified low voltage AliveCor tracings.
He told me that the cause is often a vertically oriented heart and that recording using the lead II technique can often solve the problem.
Lead II involves putting one electrode on your left knee and one your right fingers as described in this video:
Reader “J” recently sent me a series of Kardia ECG recordings, some of which were unclassified , some normal and one read as possible atrial fibrillation.
The unclassified and possible AF tracings looked like this:
They were very regular with a rate between 80 and 100 BPM but they totally lacked p waves. It was not clear to me what the rhythm was on these tracings.
Other tracings had lowish voltage but the p waves were clearly visible and Kardia easily classified them as normal
Still others had improved QRS voltage with clear p waves and were also classified appropriately as normal
After some back and forth emails we discovered that the ECG recordings with no p waves were always made using the chest lead recording. AliveCor-describes this as follows:
For an Anterior Precordial Lead, the device can be placed on the lower left side of the chest, just below the pectoral muscle. The bottom of the smartphone or tablet should be pointing towards the center of the body.
There is an abnormal cardiac rhythm that is regular between 80 and 100 BPM with no p waves and normal QRS called junctional tachycardia but in J’s case the absent p waves are related to the recording site.
Also, note that for this young woman the lead II voltage (Type B tracing) is much higher than the standard, lead I voltage (type A tracing).
Lead II With Pants On
After Dr. Albert told me of the advantages of Lead II I responded that it seemed somewhat awkward to take one’s pants off in order to make an ECG recording.
He immediately reached in his suit pocket and pulled out a pen-shaped device and began spraying a liquid on his left knee.
To my surprise he was able to make a perfect Lead II recording without taking his pants off!
Lessons learned from reader J and Dr. A:
Consider trying different leads if the standard Lead I (left hand, right hand) is consistently yielding unclassified ECG recordings
Try Lead II (left knee, right hand) to improve voltage and recording quality
You can record off your knee even with your pants on if you are prepared to spray liquids on your pants
In March of 2017 AliveCor introduced Kardia Pro, a cloud-based software platform that allows physicians to monitor patients who use the Kardia mobile ECG device.
I have been utilizing the Kardia mobile ECG device since 2013 with many of my atrial fibrillation (AF) patients and have found it be very useful as a personal intermittent long term cardiac monitor. (see here and here)
I signed up for the Kardia Pro service about 3 months ago and all of my patients who purchased Kardia devices prior to March of 2017 have been migrated automatically to Kardia Pro by AliveCor.
Now (post March 2017), patients who acquire a Kardia device must sign up for the Kardia Pro service at $15 per month to connect with a physician.
I think this is money well spent and I’ll demonstrate how the service works with a few examples.
Monitoring Patients With Atrial Fibrillation
I saw a 68 year old man with persistent atrial fibrillation that was first diagnosed at the time of pneumonia in late 2017.
He underwent a cardioversion after recovering from the pneumonia but quickly reverted back to AF. His prior cardiologist offered him the option of repeat cardioversion and long term flecainide therapy for maintenance of normal sinus rhythm (NSR) but he declined.
When I saw him for the first time in the office a month ago I listened to his heart and to my surprise, noted a regular rhythm: an AliveCor recording in the office confirmed he was in NSR. The patient had been unaware of when he was in or out of rhythm
We discussed methods for monitoring his rhythm at this point which include a 24 Holter monitor, a 7 to 14 day Long Term Monitor, a Cardiac Event Monitor and a Mobile Cardiac Outpatient Telemetry device. These devices are helpful and although expensive are often covered by insurance. They require wearing electrodes or a patch continuously and the results are not immediately available.
I also offered him the option of monitoring his AF using a Kardia device with the recordings connected to me by Kardia Pro.
He purchased the device on his own for $99, downloaded the app for his smartphone and began making recordings.
I enrolled him in my Kardia Pro account and he received an email invitation with a code that he entered which connected his account with mine, allowing me to view all of his recordings as they were made.
When I log into my Kardia Pro account I can now view a graphic display of the recordings he has made with color coding of whether they were considered normal or abnormal by Kardia.
The patient overview page also displays BP information if the patient is utilizing certain Omron devices which work with Kardia.
The display shows that after our office visit he maintained NSR for 3 days (green dots) and then intermittently had ECG recordings classified as AF (yellow dots) or unclassified (black).
The more he used the device and got feedback on when he was in or out of rhythm the more he was able to recognize symptoms that were caused by AF.
I can click on any of the dots and six second strips of the full recording are displayed. In the example below I clicked on 2/27 which has both an unclassified recording (which is atrial flutter) and an AF recording
Clicking on the ECG strips brings up the full 30 second recording on a page that also allows me to assign my formal interpretation. In the example below I added atrial flutter as the diagnosis, changing it from Kardia’s unclassified (Kardia’s algorithm calls anything it cannot clearly identify as AF that is over 100 BPM as unclassified.)
The ECG can then be archived or exported for entry into an EHR.
The benefits of this patient being connected
to me are obvious: we now have an instantaneous patient-controlled method for knowing what his cardiac rhythm is doing whether he is having symptoms or not.
This knowledge allows me to make more informed treatment decisions.
The Kardia Pro Dashboard
When I log into kardia pro I see this screen.
It contains buttons for searching for a specific patient or adding a new patient. Adding new patients is a quick and simple process requiring input of patient demographics including email and birthdate.
From the opening screen you can click on your triage tab. I have elected to have all non normal patient recorded ECGS go into the triage tab.
Another patient’s Kardia Pro page shows that he records an ECG nearly every day and most of the time Kardia documents NSR in the 60s. Overall, he has made 773 recordings and 677 of them were NSR, 28 unanalyzed (due to brevity) , 13 unclassified and 55 showing AF.
Monitoring Rate Control In Patients With AF and Reversion Post-Cardioversion
Another patient I saw for the first time recently has had long-standing persistent AF. His previous cardiologist performed an electrical cardioversion a year ago but the patient reverted back to AF in 40 hours. Before seeing me he had purchased a Kardia mobile ECG device and was using it to monitor his heart rate.
After he accepted my email invitation to connect via Kardia Pro I was able to see his rhythm and rate daily. The Kardia Pro chart belowshows his daily heart rate while in atrial fibrillation. We utilized this to guide titration of his rate controlling medications. Such precise remote monitoring of heart rate in AF (which is often difficult to accurately assess by standard heart rate devices) obviates the need for office visits for 12 lead ECGs or periodic Holter monitors.
I performed a second cardioversion on him after which he made daily recordings documenting maintenance of NSR. With this system we can determine exactly when AF returns, information which will be very helpful in determining future treatment options.
Kardia Pro Plus Kardia Mobile ECG Creates Personal Intermittent Long Term Rhythm Monitor
There are many potential applications of the Kardia ECG device beyond AF monitoring (assessing palpitations, PVCs, tachycardia, etc.) but they are all enhanced when the device is combined with a good cardiologist connected to the device by Kardia Pro.
I’ve gotten spoiled by the information I get from my AF patients who are on Kardia Pro now. When they call the office with palpitations or a sense of being out of rhythm I can determine within a minute what their rhythm is wherever I am (excluding tropical beaches and mountain tops) or wherever the patient is (for the most part.)
On the other hand patients who are not on Kardia Pro have to come into the office for 12-lead ECGs. When they call I feel like my diagnostic tools are limited. Such patients usually end up getting one of the standard Long Term Monitoring (LTM) Devices. If I am fortunate, after a few days to weeks , the results of the LTM will be faxed to my office.
I am optimistic based on this early experience with Kardia Pro that ultimately this service in conjunction with the Kardia Mobile ECG device (or similar products) will replace many of the more expensive and inconvenient long term monitoring devices that cardiologists currently use.
The KardiaBand for Apple Watch from AliveCor has delivered on its unique promise of a medical grade single lead ECG recording made by placing your thumb on your wristwatch band.
The ECG recordings are equivalent in quality to those made by their previously available KardiaMobile (see my prior post here.) After more experience with the Band I think the ease of recording is superior to KardiaMobile and the ability to discriminate atrial fibrillation from normal sinus rhythm is similar to KardiaMobile.
By combining either a KardiaBand or a KardiaMobile device with Kardia’s SmartRhythm monitoring system for Apple Watch we now have the promise of personal monitoring to detect atrial fibrillation.
What is SmartRhythm?
SmartRhythm is AliveCor’s term for its system for monitoring your heart rate and activity levels in order to identify when your rhythm is abnormal.
The system “takes your heart rate and activity data gathered from the Apple Watch and evaluates it using a deep neural network to predict your heart rate pattern.”
The heart rate is obtained from the Apple Watch PPG sensor every 5 seconds. If it differs from what is predicted SmartRhythm notifies you to record an ECG.
If you’d like to learn more detail about the development of SmartRhythm and how it functions, AliveCor has an excellent informational piece here.
You can choose to have the Kardia SmartRhythm display come up whenever your Apple Watch awakens. It’s got information on your heart rate and activity over the preceding several hours
The AliveCor FAQ on SmartRhythm stresses that a notification does not always mean an abnormal rhythm. Clearly false positives can and will occur. The first day I wore my KardiaBand I had several of these.
Causes for false positives include exercise that Apple Watch couldn’t detect, stress or anxiety-in other words, situations where your heart rate is higher than predicted by how much activity you are doing.
The long term record of your SmartRhythm recordings resides on your iPhone . Here’s my record for the last week
Note that Kardia , in addition to tracking your heart rate, also shows you by the green, yellow and orange dots, the times that ECG recordings were made.
Green dots indicate recordings classified as normal and yellow as “unclassified.” In my case most of the unclassified recordings were due to heart rate >100 BPM associated with exercise.
There is one orange dot indicating that Kardia felt the ECG showed “possible atrial fibrillation.”
This happened when I took my Apple Watch off my wrist and put it on one of my patients who has permanent atrial fibrillation. I had him push on the KardiaBand sensor to make an ECG recording and it was correctly identified as atrial fibrillation.
Thus far I have had no notifications of “possible atrial fibrillation” while I have been wearing my watch thus the false positive rate appears acceptably low.
How Does SmartRhythm Perform During Exercise?
I checked out SmartRhythm’s ability to predict normal and abnormal heart patterns by wearing it during a session on my indoor bike trainer. The device did a good job of tracking both my heart rate and activity during the workout. You can view the most recent data by viewing your Apple Watch screen during the workout as below
Or for more detailed information you can view the complete history on your iPhone as below
The system accurately tracked my heart rate and activity (although AliveCor lists stationary bike as an activity that may result in false positives). During a session of weights after the aerobic workout despite erratic heart rates and arm movements it did not notify me of an abnormality. I also did 100 jumping jacks (which involves wildly flailing my arms) and the heart rate remained within the predicted boundaries.
What is more remarkable is that I was able while cycling at peak activity to make a very good quality ECG recording by taking my right hand off the handle bar and pushing my thumb down on the KardiaBand sensor on my left wrist.
This recording clearly displays p waves and is sinus tachycardia. It’s unclassified by Kardia because the rate is >100 BPM.
Afib Patient Experience
One of my patients last week, a 70 year old woman with paroxysmal atrial fibrillation, had already set up SmartRhythm monitoring on her Apple Watch.
I have this patient like many of my afibbers utilizing KardiaMobile to check an ECG when they think they are in afib.
However, she, like many of my afib patients, is totally unaware when her heart is out of rhythm. Such asymptomatic patients are alerted to the fact that they are in afib by detection of a rapid heart rate (from a heart rate tracking wearable or BP monitor) or an irregular heart beat (from BP monitor or by someone checking the pulse) or by a random recording of an ECG.
She’s started using SmartRhythm in the hopes that it will provide a reliable and early warning of when she goes into atrial fibrillation.
We discussed the possibility of stopping the flecainide she takes to maintain normal rhythm to test the accuracy of the SmartRhythm system for detecting atrial fibrillation in her but decided not to. She’s on an oral anticoagulant and therefore protected from stroke so development of atrial fibrillation will not be dangerous for her.
I eagerly await the first real world, real patient reports of SmartRhythm’s performance in atrial fibrillation detection.
If there are any afibbers out there who have had an episode of atrial fibrillation detected by SmartRhythm please let me know the details.
We need such anecdotes along with controlled trials to determine how useful SmartRhythm will be as a personal wearable system for detection of afib.
N.B. I’ve copied a nice section from AliveCor’s website which describes in detail the difference between measuring heart rate from the PPG sensor that all wearable devices use versus measuring the electrical activity of the heart with an ECG.
To understand how Kardia for Apple Watch works, let’s start by talking about your heart, how the Apple Watch and other wearable devices can measure your heart rate, and how an ECG is different from the information you get from a heart rate sensor alone.
Your heart is a pump. With each beat of your heart, blood is pumped through your arteries and causes them to expand. In the time between beats, your arteries relax again. On the underside of the Apple Watch is a sensor, called a photoplethysmogram (PPG), that uses green and infrared LEDs to shine light onto your skin, and detects the small changes in the amount of light reflected back as your arteries expand and relax with each beat of your heart. Using this sensor, the Apple Watch can tell how fast your heart is beating, and how your heart rate changes over time.
But, your heart rate does not tell everything there is to know about your heart. The PPG sensor on the Apple Watch can only see what happens after each heartbeat, as blood is pumped around your body. It can’t tell you anything about what is making your heart beat, or about what happens inside your heart during each beat. An ECG is very different, and tells you a lot more!
An ECG measures the electrical activity in your heart muscles. It detects the small pulse of electricity from the sinoatrial node (the body’s natural pacemaker, which normally initiates each heartbeat) and the large electrical impulses produced as the lower chambers of the heart (the ventricles) contract and relax. By looking at an ECG, a doctor can discern a wealth of information about the health and activity of your heart muscle, much more than you can tell from your heart rate alone. ECGs are the required gold standard for diagnosis of arrhythmias and many cardiac abnormalities, and can even be used to see evidence of acute heart attacks and even events that have occurred in the past.
Research has shown that taking frequent ECGs increases the likelihood of detecting certain arrhythmias, and decreases the mean time to diagnosis.
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.
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:
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.
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.
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.
The Skeptical Cardiologist is a strong proponent of empowering patients with atrial fibrillation by utilizing personal cardiac rhythm devices such as Afib Alert or AliveCor’s Kardia.
I’ve written about my experiences with the initial versions of the Kardia mobile ECG device and the service it provides here and here.
I have been monitoring dozens of my afib patients using AliveCor’s Physician Dashboard.
Recently AliveCor changed fundamentally the way their app works such that for new users much of the functionality I described in my previous posts now requires subscribing to their Premium service which costs $9.99 per month or $99 per year.
What Has Changed With The Kardia App
The Kardia device which works with both iOs and Android smart
phones is unchanged and still generates a “medical-grade” single lead rhythm strips which appears within the Kardia app.
The app still is reasonably accurate at identifying atrial fibrillation or normal heart rhythms and offers a fee-based service for interpretation of unclassified ECGs.
However, for new purchasers of Kardia, the capability to access, email or print prior ECG recordings has gone away. Prior to March of this year, Kardia users could access prior ECG tracings which were stored in the cloud by touching the “Journal” button on the app. These older tracings could be emailed and they were available through the cloud for a physician like myself to review at any time.
Now new Kardia purchasers will find that when they make an ECG recording they have the option to email a PDF of the ECG but once they hit the DONE button it is gone and is not stored anywhere.
For my patients purchasing after March, 2017 this means that unless they purchase Kardia Premium service I will not be able to view their ECG recordings online.
An AliveCor account executive summarized for me the changes as follows:
We added a significant number of features over the past year and a half, and grandfathered all users on March 16th, 2017. New users now have the option to download and use Kardia for free, but the premium services are $9.99/mo or $99/year. Kardia Premium allows unlimited storage and history of their EKGs, summary reports with longitudinal data, blood pressure monitoring and tracking weight and medication.
Why Journal Functionality Is Important
If you purchased your AliveCor/Kardia device prior to March 16th, 2017 ago the journal functionality still works. Let’s call such customers “Journal Grandfathered”.
This Journal functionality is important in a number of ways:
My Journal Grandfathered patients can bring their phones with them during an office visit and we can review all of their ECG tracings.
Journal gGandfathered Kardia users can email their old tracings to their physicians or to anyone they wish (even the skeptical cardiologist!). They can also print them out and save PDFs of the tracings.
I can view through my online physician account all of my Journal Grandfathered patients. This means any time a patient of mine makes a recording that is unclassified or suggests atrial fibrillation I can be notified and immediately view it online.
This fundamental change took place as AliveCor attempts to convince purchasers of the Kardia device to use their Premium service.
Why AliveCor Changed The Kardia App Function
Dr. David Albert, inventor and cardiologist and the founder of AliveCor was kind enough to talk with me about this change.
He indicates that of the 150,000 AliveCor users, 10,000 are now using the Kardia Premium service. About 20% of new users elect Kardia Premium.
Prior to the change all AliveCor users had their old ECG recordings stored in the cloud in a HIPPA compliant fashion. This free service was costing AliveCor quite a bit and the company felt it was best to switch to a subscription service to provide this secure cloud storage.
With the change to the (relatively inexpensive) subscription service, patients will get additional features. As the AliveCor account executive described:
Kardia Premium allows unlimited storage and history of their EKGs, summary reports with longitudinal data, blood pressure monitoring and tracking weight and medication.
I’ve looked at the Premium service and it seems quite useful when combined with a connected physician utilizing Kardia Pro. I’ll evaluate the Premium service and the physician Kardia Pro service further and write a full post on its features in the near future.
If you are not grandfathered and want to stick with the Basic Kardia service you still have an immensely useful and inexpensive device which allows personal detection of your cardiac rhythm. Just remember to email yourself the ECG recording you just made before you hit DONE.
The skeptical cardiologist has many patients who are successfully using their AliveCor/Kardia devices to monitor for episodes of atrial fibrillation (afib).
However, a significant number of patients who have had atrial fibrillation also have premature beats. Sometimes patients feel these premature beats as a skipping or irregularity of the heart beat. Such palpitations can mimic the feeling patients get when they go into atrial fibrillation.
The ideal personal ECG monitor, therefore, would be able to reliably differentiate afib from premature beats for such patients.
Premature Beats: PVCs and PACs
I’ve discussed premature ventricular contractions (PVCs) here and here. Premature beats can also originate from the upper chambers of the heart or atria.
Such premature atrial contractions (PACs) have generally been considered benign in the past but a recent study showed that frequent (>30 s per hour) PACs or runs of >20 PACs in a row were associated with a doubling of stroke risk.
For patients who experience either PVCs or PACs the AliveCor device is frequently inaccurate.
PACs Misdiagnosed As Atrial Fibrillation
Here is a panel of recordings made by a patient of mine who has had documented episodes of atrial flutter in the past and who monitors his heart rhythm with Alivecor regularly:
Of the ten recordings , four were identified as “possible atrial fibrillation.”
Unfortunately only one of the four “possible atrial fibrillation” recordings has any atrial fibrillation: this one has 7 beats of afib initially then changes to normal sinus rhythm (NSR).
The other 3 recordings identified by AliveCor as afib are actually normal sinus rhythm with premature beats.
In addition, frequently for this patient AliveCor yields an “Unclassified” reading for NSR with PACs as in this ECG:
PVCs Misread As Atrial Fibrillation
I wrote about the first patient I identified in my office who had frequent PVCs which were misdiagnosed by AliveCor as afib here.
Since then, I’ve come across a handful of similar misdiagnoses.
One of my patients began experiences period palpitations 5 years after an ablation for atrial fibrillation. He obtained an AliveCor device to rec ord his rhythm during episodes.
For this patient,, the AliveCor frequently diagnoses “possible atrial fibrillation” but all of his episodes turn out not to be afib. In some cases he is having isolated PVCs:
At other times he has periods of atrial bigeminy which are also called afib by AliveCor. In this tracing he has atrial bigeminy and a PVC.
PVCs Read As Normal
Premature beats sometimes are interpreted by AliveCor as normal. A reader sent me a series of recordings he had made when feeling his typical palpitations. all of which were called normal. Indeed, all of them but one showed NSR. However on the one below the cause of his palpitations can be seen: PVCs.
I obtained the “Normal” tracing below from a patient in my office with a biventricular pacemaker and frequent PVCs who had no symptoms.
PVCs Read As Unclassified
A woman who had undergone an ablation procedure to eliminate her very frequent PVCS began utilizing AliveCor to try to determine if she was having recurrent symptomatic PVCs. She became quite frustrated because AliveCor kept reading her heart rate at 42 BPM and giving her an unclassified reading.
AliveCor is always going to call rhythms (other than afib) unclassified when it counts a heart rate less than 50 BPM or greater than 100 BPM.
In this patient’s case, every other beat was a PVC (red circles). Her PVCs are sufficiently early and with low voltage so the AliveCor algorithm cannot differentiate them from T Waves and only counts the normal sinus beats toward heart rate.
Accurate AliveCor Readings
I should point out that many of my patients get a very reliable assessment from their devices. These tracings from a woman with paroxysmal atrial fibrillation are typical: all the Normal readings are truly normal and all the atrial fibrillation readings are truly atrial fibrillation with heart rates above 100.
The Normal Detector in the AliveECG app notifies you when a recording is “normal”. This means that the heart rate is between 50 and 100 beats per minute, there are no or very few abnormal beats, and the shape, timing and duration of each beat is considered normal.
What qualifies as “very few” abnormal beats is not clear. The manual goes on to state that the AliveCor normal detector has been designed to be conservative with what it detects as normal.
What is clear is that premature beats significantly confuse the AliveCor algorithm. Both PVCs and PACs can create a false positive diagnosis of atrial fibrillation when it is not present.
Consequently, if you have afib and premature beats you cannot be entirely confident that a reading of afib is truly afib. Strongly consider having the tracing reviewed by a cardiologist before concluding that you had afib.
On the other hand if you are experiencing palpitations and make a recording with Alivecor that comes back as normal do not assume that your heart rhythm was totally normal. While highly unlikely to be afib, your palpitations could still be due to PACs or PVCs.
If a patient of mine has an abnormal or questionable AliveCor recording it is currently a very simple process for me to review the recording online through my AliveCor doctor dashboard. The recordings can also be emailed to me.
However, Kardia appears to be trying to move new AliveCor purchasers to a subscription or Premium service. In addition, Kardia keep giving me messages that “the doctor dashboard is going away.”