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.
AliveCor’s Official Position on Premature Beats
The AliveCor manual states
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.
Coralively Yours,
-ACP
Navigating Treatment Options For Atrial Fibrillation 
Skipping the “doctor dashboard” might have an impact on their regulatory compliance requirements …
Unclear why they don’t solve that PVC issue and even add other arrythmia detection, as algorithms exist since decades.
Sooner or later they risk being obsoleted by low cost ecg+ patches
LikeLike
Agree with Johan definitely. It’s quite uncertain why they can’t solve the PVC issue.
LikeLike
I have many PVCs PA C’s and short bursts of afib I understand everything you are saying about the alivecor even though I do love mine as well I would be very interested in being able to send you an occasional reading to look at for me even for a fee what would I have to do to be one of your patientsand get this service.
LikeLike
Had about ten ectopics while recording but result was normal. Another time because my heart beat was fast its result ‘unclassified ‘ confusing as purpose of recording is to confirm and show these changes.
LikeLike
I am a 63 year old obese male. I was one of the original users of alivecor. I have experienced every one of the items you discussed about on multiple occasions. I live in Utah but would love to be able to send you recordings to review for me even if there is a fee.
Is that possible?
P.S. Even with the flaws I love my alivecor unit. It has made living with pvc, pacs, short runs of afib much easier. I have these for 30 years I can feel everyone, that’s why it is so hard to live with for me.
Best regards,
Kim
LikeLike
Kim,
I’m glad the device has helped you deal with your arrhythmias.
I find it to be an indispensable tool for many of my patients.
I haven’t established any method for charging fees but
If you want to email your unclassified tracings to DRP@theskepticalcardiologist.com I can review them as time allows
LikeLike
I have a kardia app but it says each time it’s a normal reading even though occasionally I’m feeling a couple of missed beats or pause. Also I’ve had a couple that came back as unclassified as my heart rate was 110 bpm. Does this mean the missed beats are normal or they havnt been picked up? Thank you
LikeLike
Kardia is going to classify sinus rhythm with premature beats (PVCS or PACs) as “normal” most of the time. It does not identify the PVCS or PACS. Sometimes (rarely) it mistakes the premature beats for atrial fibrillation and sometimes it calls the recording “unclassified”.
LikeLike
If you want to email your unclassified tracings to DRP@theskepticalcardiologist.com I can review them as time allows
LikeLike
I am a user of Kardia. I don’t know who was reading these but I have a recent trace with 5 consecutive PVCs that was deemed no problem. I happen to know something about electrocardiography and they are classic examples. This is an interesting toy but apparently it has difficulty even recognizing an aberrant sinus rhythm.
LikeLike
It is not currently aimed at detecting PVCS. See my post today to see how effective it is in managing afib, however.
That being said, the device records a good quality single lead ECG which if read by a physician can easily diagnose PVCs.
LikeLike
I have bigeminy and skipped every beat which I can’t seem to find a name for
LikeLike
How are you feeling now ? i have alot of symptomatic pvc beats too in bigeminy (mostly at rest)
LikeLike
A recent ski trip at high altitude resulted in an increase in BP, and the appearance of PACS for the first time. The first signal of PACS was a wiggly heart symbol, both on the old Omron and the new Bluetooth Qardia. Both new Apple Watch 4 and the Kardia band on the old AW3 indicated irregularities. The local cardiologist confirmed PACS on full ECG.
These devices are working as intended as warning signals to seek further advice. Whilst the cardiologist was complacent about PACS some lifestyle changes seem to be helping, as I am mindful that PACS may be a harbinger of further problems.
LikeLike