As I pointed out Friday, Apple’s claim that the ECG sensor on their new Apple Watch 4 (available “later this year”) is “the First ECG product offered over the counter directly to consumers” is totally bogus.
AliveCor’s Kardia mobile ECG device was approved by the FDA for over the counter direct to consumer sales on February 10, 2014. Apple had to have known this as they worked with AliveCor to bring the first Apple Watch based ECG device to FDA approval in 2017.
I tried but failed to get AliveCor founder Dr. David Albert’s thoughts on Apple’s disinformation but Yahoo finance was able to speak to Vic Gundotra, the CEO of AliveCor:
Over at the headquarters of AliveCor, a startup based in Google’s hometown of Mountain View, they, too, were surprised by the announcement, CEO Vic Gundotra said in a phone interview on Thursday. Gundotra is a former Googler, widely known as the executive behind the Google+ social network.
Gundotra was also surprised by Apple’s claims of ECG primacy
“We were watching [the announcement], and we were surprised,” Gundotra said. “It was amazing, it was like us being on stage, with the thing we’ve been doing for 7 years,” referring to AliveCor’s product for detecting atrial fibrillation (AFib), a tough-to-spot heart disorder that manifests as an irregular, often quick heart rate that can cause poor circulation.
“Although when they said they were first to go over-the-counter, we were surprised,” he continued. “Apple doesn’t like to admit they copy anyone, even in the smallest things. Their own version of alternative facts.”
One man’s alternative fact is another (less polite) man’s lie.
Gundotra apparently views Apple’s entry as a good thing
“We love that Apple is validating AFib; just wait until you see what AliveCor is going to do next,” he said. “We were a great restaurant in a remote section of town, and someone just opened a giant restaurant right next to us, bringing a lot more attention.”
And as I pointed out previously, the AliveCor mobile ECG device (not the Kardia Band) is significantly cheaper than an Apple Watch and has multiple studies showing its accuracy. Interestingly, Gundotra indicates AliveCor sales has increased after the Apple announcement,.
“Ours is $99, theirs is $399, our sales popped yesterday, big time,”
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 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.”
The skeptical cardiologist has been testing the comparative accuracy of two hand-held mobile ECG devices in his office over the last month. I’ve written extensively about my experience with the AliveCor/Kardia (ACK) device here and here. Most recently I described my experience with the Afib Alert (AA) device here.
Over several days I had my office patients utilize both devices to record their cardiac rhythm and I compared the device diagnosis to the patient’s true cardiac rhythm.
In 14 patients both devices correctly identified normal sinus rhythm. AFA does this by displaying a green check mark , ACK by displaying the actual recording on a smartphone screen along with the word Normal.
The AFA ECG can subsequently uploaded via USB connection to a PC and reviewed in PDF format. The ACK PDF can be viewed instantaneously and saved or emailed as PDF.
Normal by AFA/Unreadable or Unclassified by AliveCor
In 5 patients in normal rhythm (NSR) , AFA correctly identified the rhythm but ACK was either unreadable (3) or unclassified (2). In the not infrequent case of a poor ACK tracing I will spend extra time adjusting the patient’s hand position on the electrodes or stabilizing the hands. With AFA this is rarely necessary.
In this 70 year old man the AFA device recording was very good and the device immediately identified the rhythm as normal.
ACK recording was good quality but its algorithm could not classify the rhythm.
A 68 year old man who had had bypass surgery and aortic valve replacement had a very good quality AFA recording with correct classification as NSR
AliveCor/Kardia recordings on the same patient despite considerable and prolonged efforts to improve the recording were poor and were classified as “unreadable”
There were 3 cases were AFA diagnosed atrial fibrillation (AF) and the rhythm was not AF. These are considered false positives and can lead to unncessary concern when the device is being used by patients at home. In 2 of these ACK was unreadable or unclassified and in one ACK also diagnosed AF.
A 90 year old woman with right bundle branch block (RBBBin NSR was classified by AFA as being in AF.
The ACK algorithm is clearly more conservative than AA. The ACK manual states:
If you have been diagnosed with a condition that affects the shape of your EKG (e.g., intraventricular conduction delay, left or right bundle branch block,Wolff-Parkinson-White Syndrome, etc.), experience a large number of premature ventricular or atrial contractions (PVC and PAC), are experiencing an arrhythmia, or took a poor quality recording it is unlikely that you will be notified that your EKG is normal.
One man’s rhythm confounded both AFA and AC. This gentleman has had atrial flutter in the past and records at home his rhythm daily using his own AliveCor device which he uses in conjunction with an iPad.
During our office visits we review the recordings he has made. He was quite bothered by the fact that he had several that were identified by Alivecor as AF but in fact were normal.
A recording he made on May 2nd at 845 pm was read as unclassified but with a heart rate of 149 BPM. The rhythm is actually atrial flutter with 2:1 block.
Sure enough, when I recorded his rhythm with ACK although NSR (with APCS) it was read as unclassified
AFA classified Lawrence’s rhythm as AF when it was in fact normal sinus with APCs.
One patient a 50 year old woman who has a chronic sinus tachycardia and typically has a heart rate in the 130s, both devices failed.
We could have anticipated that AC would make her unclassified due to a HR over 100 worse than unclassified the tracing obtained on her by AC (on the right)was terrible and unreadable until the last few seconds. On the other hand the AFA tracing was rock solid throughout and clearly shows p waves and a regular tachycardia. For unclear reasons, however the AFA device diagnosed this as AF.
Accuracy in Patients In Atrial Fibrillation
In 2/4 patients with AF, both devices correctly classified the rhythm..
In one patient AFA correctly diagnosed AF whereas ACK called it unclassified.
This patient was in afib with HR over 100. AFA correctly identified it whereas ACK called in unclassified. The AC was noisy in the beginning but towards the end one can clearly diagnose AF
In one 90 year old man AFA could not make the diagnosis (yellow)
ACK correctly identified the rhythm as AF
One patient who I had recently cardioverted from AF was the only false positive ACK. AliveCor tracing is poor quality and was called AF whereas AFA correctly identified NSR>
The sensitivity of both devices for detecting atrial fibrillation was 75%.
The specificity of AFA was 86% and that of ACK was 88%.
ACK was unreadable or unclassified 5/26 times or 19% of the time.
The sensitivity and specificity I’m reporting is less than reported in other studies but I think it represents more real world experience with these types of devices.
In a head to head comparison of AFA and ACK mobile ECG devices I found
-Recordings using AfibAlert are usually superior in quality to AliveCor tracings with a minimum of need for adjustment of hand position and instruction.
-This superiority of ease of use and quality mean almost all AfibAlert tracings are interpreted whereas 19% of AliveCor tracings are either unclassified or unreadable.
-Sensitivity is similar. Both devices are highly likely to properly detect and identify atrial fibrillation when it occurs.
-AliveCor specificity is superior to AfibAlert. This means less cases that are not AF will be classified as AF by AliveCor compared to AfibAlert. This is due to a more conservative algorithm in AliveCor which rejects wide QRS complexes, frequent extra-systoles.
Both companies are actively tweaking their algorithms and software to improve real world accuracy and improve user experience but what I report reflects what a patient at home or a physician in office can reasonably expect from these devices right now.
The skeptical cardiologist has had several of his readers submit stories and tracings of AliveCor Mobile ECG recordings which yield unclassified or unreadable recordings. In some cases this is due to excess noise but a lot of these tracings suffer from low voltage: the height of the tracing is very small.
John, a skepcard reader, is typical.
Recently, he noted his heart was racing and made an AliveCor recording which came back interpreted by the app as normal
Three hours later he made a second recording which has drastically lower voltage: the only deflections visible are tiny QRS complexes, the p waves have disappeared. I think this is also normal sinus rhythm but because p waves can’t be seen this came back uninterpretable and if there were any irregularity AliveCor would have called it atrial fibrillation:
John has a theory on the cause of some of his low voltage recordings which I shall reveal in a subsequent post after testing it.
In the meantime, if any readers have suggestions as to causes of low voltage recordings or have noted similar issues please comment below or send recordings and observations to DRP@theskepticalcardiologist.com.
The skeptical cardiologist has often sung the praises of the AliveCor Mobile ECG for home and office heart rhythm monitoring (see here and here.) However, there is a significant rate of failure of the device to accurately identify atrial fibrillation. I’ve seen numerous cases where the device read afib as “unclassified” and normal sinus rhythm (usually with PVCs or PACs) called afib both in my office and with my patient’s home monitors.
In such cases it is easy for me to review my patient’s recordings and clarify the rhythm for them.
For those individuals who do not have a cardiologist available to review the recordings, AliveCor offers a service which gives an option of having either a cardiac technician or cardiologist review the tracing. The “cardiac technician assessment” costs $9 and response time is one hour. The “Clinical Analysis and Report by a U.S. Board Certified Cardiologist” costs $19 with 24 hour response time.
Obviously, I have no need for this service but I’ve had several readers provide me with their anecdotal experiences with it and it hasn’t been good.
One reader who has a familial form of hypertrophic cardiomyopathy utilizes his AliveCor device to monitor for PVCs. One day he made the following recording which AliveCor could not classify:
He then requested a technician read which was interpreted as “atrial fibrillation sustained.”
He then had requested the cardiologist reading which came back as Normal Sinus Rhythm.
Finally, he again requested the technician read and got the correct reading this time which is normal sinus rhythm with PACs
When my reader protested to Kardia customer service about this marked inconsistency: three different readings in a 24 hour period, a Kardia customer service rep responded :
I was able to review this with our Chief Medical Officer who advised that the recording shows Sinus Rhythm with PACs. The Compumed report seldom provides identification of PACs and PVCs as most cardiologists believe they are not significant findings. The sustained AFib finding was incorrect, so I have refunded the $5 fee you had paid.
Please let us know if you have any other questions.
As I pointed out in my post on palpitations, most PVCS are benign but some are not and patients with palpitation would like to know if they are having PVCS and/or PACs when they feel palpitations.
More importantly, the misdiagnosis of afib when the rhythm is NSR with PACs or PVCs can lead to extreme anxiety.
Heres a recording
I made in my office this morning on a patient with cardiomyopathy and a defibrillator.
This is very clearly NSR with PVCs yet AliveCor diagnosed it as “possible atrial fibrillation.”
The AliveCor algorithm is not alone in making frequent errors in the diagnosis of atrial fibrillation.
The vast majority of ECGs performed in the US come with an interpretation provided by a computerized algorithm and medical personnel rely on this interpretation until it can be verified or corrected by an overreading cardiologist.
One study demonstrated that computerized ECG interpration (ECG-C) is correct only 54% of the time when dealing with a rhythm other than sinus rhythm
Another study found that 19% of ECG-C misinterpreted normal rhythm as atrial fibrillation. Failure of the physician ordering the ECG to correct the inaccurate interpretation resulted in change in management and initiation of inappropriate treatment, including antiarrhytmic medications and anticoagulation, in 10% of patients. Additional unnecessary diagnostic testing was performed based on the misinterpreted ECGs in 24% of patients.
When lives or peace of mind are at risk you want your ECG interpreted by a cardiologist.
I would like to take this opportunity to personally issue a challenge to IBM’s Watson.
Hey, Watson, I bet $1,000 I can Interpret cardiac rhythm from an ECG with more accuracy than you can!
The AliveCor/Kardia mobile ECG device is a really nifty way to monitor your heart rhythm. Since acquiring the third generation device (which sits within or on my iPhone case and communicates with a smartphone app) I have begun routinely using it on my patients who need a heart rhythm check during office visits. It saves us the time, inconvenience (shirt and bra removal) and expense of a full 12-lead ECG which I would normally use.
In addition, I’ve convinced several dozen of my patients to purchase one of these devices and they are using it regularly to monitor their heart rhythms. Typically, I recommend it to a patient who has had atrial fibrillation (Afib) in the past or who has intermittent spells of palpitations.
Some make daily recordings to verify that they are still in normal rhythm and others only make recordings when symptoms develop.
Once my email invitation request is accepted I can view the ECGs recorded by my patients who have AliveCor devices as I described here.
This monitoring has in many cases taken the place of expensive, obtrusive and clumsy long term event monitors.
In general, it has been very helpful but the device/app makes occasional mistakes which are significant and sometimes for certain patients it does a poor job of making a good recording.
Alivecor Success Stories
One of my patients, a spry ninety-something year young lady makes an AliveCor recording every day, since an episode of Afib 9 months ago.
And when I say every day I mean it literally everyday. It could be because she is compulsive or perhaps she has programmed the AliveCor to remind her. When I log in to the AliveCor site and click on her name I can see these daily recordings:
After a month of normal daily recordings, she suddenly began feeling very light headed and weak with a sensation that her heart was racing.
She grabbed her trusty iPhone and used the AliveCor device attached to it to make a recording of her cardiac rhythm. This time, unlike the dozens of other previous recordings, the device indicated her heart rate was 157 beats per minutes , about twice as fast as usual.
After 5 hours her symptoms abated and by the time of her next recording she had gone back to the normal rhythm.
She made two other recordings during the time she felt bad and they both confirmed Afib at rates of 140 to 150 beats per minute.
In this case, the device definitely alerted her to a marked and dramatic increase in heart rate but was not capable of identifying this as Afib In my experience with several hundred recordings, the device accurately identifies atrial fibrillation about 80% of the time. On rare occasions (see here) it has misidentified normal rhythm with extra beats as atrial fibrillation
AliveCor/kardia users have the option of having their recordings interpreted for a fee by a cardiologist or a technician.
My patients can alert me of a recording and I can go online and read the ECG myself and then contact the patient to inform them of my interpration of their heart rhythm and my recommendations.
Another patient made the recording below:Although she is at high risk of having a stroke during the times she is in Afib, we had been holding the blood thinner I had started her on because of bleeding from her mouth. I had instructed her to take daily recordings of her rhythm with the AliveCor until she was seen by her dentist to evaluate the bleeding.
In this case, the AliveCor performed appropriately, identifying correctly the presence of Afib which was the cause of her nocturnal symptoms.
A young woman emailed me that her AliveCor device on several occasions has identified her cardiac rhythm during times of a feeling of heart racing and palpitations as “possible atrial fibrillation.” When she sent the recordings in to AliveCor to have a paid interpretation, however, the recordings were interpreted as sinus tachycardia with extra beats. Indeed , upon my review her rhythm was not Afib. Clearly, when the device misidentifies Afib, this has the potential for creating unnecessary anxiety.
It is not uncommon for a full, 12-lead ECG done in the hospital or doctor’s office by complex computer algorithms to misinterpret normal rhythm as Afib so I’m not surprised that this happens with AliveCor using a single lead recorded from the fingers.
The young woman was advised by AliveCor to try a few things such as using the device in airplane mode, sitting still and wetting her fingers which did not help. She was sent a new device and the problem persisted. She finds that putting the device on her chest gives a better chance of success.
She also runs into a problem I see frequently which is a totally normal recording labeled by the device as “unclassified.”
In this example, although I can clearly see the p-waves indicating normal sinus rhythm, the voltage is too low for the device to recognize.
Send Me Your AliveCor Problems and Solutions
I’m interested in collecting more AliveCor/Kardia success and failure stories so please post yours in the comments or email me directly at DRP@theskeptical cardiologist.com.
In addition, I’m interested in any tips AliveCor users have to enhance the success of their recordings: What techniques do you use to make the signal strength and recording better? What situations have you found that tend to worsen the signal strength and recording quality?
Still Unclassified Yours,
P.S. Tomorrow is Cyber Monday and I note that Kardia is running a “Black Friday” special through 11/28, offering the device at 25% off.
P.P.S. Kardia, You should change the statement on your website, “90% of strokes are preventable if you catch the symptoms early.” makes no sense. I think you mean that some strokes are preventable (I have no idea where the 90% figure come from) if one can detect Afib by utilizing a monitoring device to assess symptoms such as palpitations or irregular heart beat.