An Early Look At AliveCor’s Amazing KardiaMobile 6L: Accurate 6 Lead ECG On Your Smartphone

The skeptical cardiologist has been evaluating a demo version of AliveCor’s new KardiaMobile 6L.

I have been a huge advocate of Kardia’s single lead ECG and use it with great success in dozens of my afib patients. I’ve written about how this personal ECG monitoring empowers patients and providers and is a crucial component of the enlightened medical management of afib.

In less than a month AliveCor plans to release its KardiaMobile 6L which will provide 6 ECG leads  using a smartphone based mobile ECG system that is similar to the Kardia single lead system.

AliveCor’s website proclaims “This is your heart x 6.”




I was fortunate enough to obtain a demo version of the 6L and have been evaluating it.

My  first impressions are that this is a remarkable step forward in the technology of personal ECG monitoring. I’m not sure if I would call it “your heart x 6” but I feel the ability to view six high quality leads compared to one is definitely going to add to the diagnostic capabilities of the Kardia device.

Kardia 6L Setup And Hardware

The 6L is similar in design and function to the single lead device.

I’m including this cool spinning video (from the AliveCor website) which makes it appear, slick, stylish and  futuristic

Once paired to the Kardia smartphone app (available for iOS or Android smartphones for free) it communicates with the smartphone  using BLE to create ECG tracings.

Like the single lead Kardia the 6L has two sensors on top for left and right hand contact. But in addition, there is a third on the bottom which can be put on a left knee or ankle.

The combination of these sensors and contact points yield the 6 classic frontal leads of a full 12 lead ECG: leads I, II, III, aVL, aVR, and aVF. This is accomplished, AliveCor points out “without messy gels and wires.

I found that using the device was simple and strait-forward and we  were able to get high quality tracings with minimal difficulty within a minute of starting the process in all the patients we tried it on.

The  Diagnostic Power Of Six Leads

Below is a tracing on a patient with known atrial fibrillation. The  algorithm correctly diagnoses it. With 6 different views of the electrical activity of the atrium I (and the Kardia algorithm)  have a better chance of determining if p waves are present, thereby presumably  increasing the accuracy of rhythm determination

Depending on the electrical vector of the left and right atria, the best lead to visualize p waves varies from patient to patient, thus having 6 to choose from should improve our ability to differentiate sinus rhythm from afib.

In the example below, the Kardia 6L very accurately registered the left axis deviation and left anterior fascicular block that we also noted on this patient’s 12 lead ECG. This 6L capability, determining the axis of the heart in the frontal plane,  will further add to the useful information Kardia provides.


For a good summary of axis determination and what abnormal axes tells us see here.

The History of ECG Leads

When I began my cardiology training the 12-lead ECG was  standard but it has not always been that way. I took this timeline figure from a nice review of the history of the ECG



Einthoven’s first 3 lead EKG  in 1901 was enormous.

Old string galvanometer electrocardiograph showing the big machine with the patient rinsing his extremities in the cylindrical electrodes filled with electrolyte solution.
 It is mind-boggling to consider that we can now record  6 ECG leads with a smartphone and a device the size of a stick of gum

For the first 30 years of the ECG era cardiologists only had 3 ECG leads to provide information on cardiac pathology.  Here’s a figure from a state of the art paper in 1924 on “coronary thrombosis” (which we now term a myocardial infarction) showing changes diagnostic of an “attack” and subsequent atrial fibrillation

In the 1930s  the 6 precordial leads were developed providing more information on electrical activity in the horizontal axis of the heart. The development of the augmented leads (aVr, aVL, aVF) in 1942  filled in the gaps of the frontal plane and the combination of all of these 12 leads was sanctified by the AHA in 1954.

I’ll write a more detailed analysis of the Kardia 6L after spending more time using it in patient care.

Specifically I’ll be analyzing (and looking for published data relative to):

-the relative accuracy of the 6L versus the single lead Kardia for afib determination (which, at this point would be the major reason for current Kardia users to upgrade.)

-the utility of the 6L for determination of cardiac axis and electrical intervals in comparison to the standard 12 lead ECG,  especially in patients on anti-arrhythmic drugs

For now, this latest output from the meticulous and thoughtful folks at AliveCor has knocked my socks off!

Stockingfreely Yours,


N.B. If one uses the single lead kardia device in the traditional manner (left hand and right hand on the sensors) one is recording ECG lead I. However, if you put your right hand on the right sensor and touch the left sensor to your left leg you are now recording ECG lead II and if to the right leg, ECG lead III.

I describe this in detail here. For certain individuals the lead II recordings are much better than lead I and reduce the prevalence of “unclassified” recordings.

My feeling is that by automatically including the leg (and leads II and III) the 6L will intrinsically provide high voltage leads for review and analysis, thereby improving the ability to accurately classify rhythm.

And (totally unrelated to the 6L discussion) one can also record precordial ECG leads by putting the device on the chest thus theoretically completing the full 12 leads of the standard ECG.

Please also note that I have no financial or consulting ties to AliveCor.  I’m just a big fan of their products.


10 thoughts on “An Early Look At AliveCor’s Amazing KardiaMobile 6L: Accurate 6 Lead ECG On Your Smartphone”

  1. Thank you for your wonderful website! At 65years old I was diagnosed with A-fib 60 days ago & had a successful (at least for now) cardio version. Rx treatment & my research/education continue.

    Now that I know a-fib can reoccur I need to monitor & document myself more closely, however I often travel and stay in areas where no internet, 3g, 4g services are available. My laptop, iPad, android phone are.

    I’m considering a KardiaMobile 6L but seems to require regular internet access to their proprietary cloud program to work/archive well. I also read it tops out at 100 BPM so after I hike up a hill & take a break I’d not be able to tell my BPM.

    The new highly rated 2019 version Emay Heart Health Tracker (white, link below) & app appears more self contained & DIY. Especially adding a decent tracing/wave “decoder” chart to my kit. Data is archive-able & still sharable when connections permit. Your earlier review of the Emay indicates you’re not a fan. Any thoughts?

    Thanks again for your generosity & time to build such a valuable resource for us newbies. – DL

    • David,
      I’m about to post a comparison of the Emay and Kardia devices by a reader/physician. Bottom line is it is very similar to the SonoHealth ECG which is virtually useless for diagnosing normal versus abnormal rhythm. All reviews on Amazon are suspect for these devices as the manufacturers are paying reviewers.
      I would stick with kardia and although I’ve written favorably about the 6L I haven’t found any distinct advantages over the single lead.
      It will record heart rates over 100 but it won’t call them normal but use the term tachycardia which just means HR >100. If it’s afib >100 it will diagnose it reliably.
      The Emay is very similar to the Sonohealth I wrote about. Although it seems more DIY it is very poor quality.
      Your question will motivate me to get the Emay /Kardia comparison post out possibly today.
      Dr P

  2. I have been using a single lead Kardia mobile to record myself when I have my “funny spells” which seem to be related to intermittent bradycardia. It worked very well for me but when I tried to use it for my husband who has a bipaced pacemaker and ICD it takes the recording but says there is too much interference every time. Will the 6 lead be any better. He has had Afib in the past and Vtach with 3 ventricular ablations this summer and is now on Milnirone pump. I suspect he is having strings of PVCs resulting in SOB whenever he exerts himself but I have no means of documenting that. Can the 6 lead Kardia mobile assist with identifying that or does it have the same problems as the single lead? Is there any other home device that might be suitable in this situation.

    • Diane,
      These are good questions. I’m not aware of any head to head comparisons of the single and the six lead Kardia for rhythm diagnosis other than the one I did.
      Therefore, although theoretically possible, it is not clear the 6L is superior for diagnosing difficult rhythms.
      AliveCor has in the past specifically said their algorithm won’t work for paced rhythms. I suspect in your husband’s case because of the biv pacemaker and PVCS no consumer device will be helpful.
      If I had the question you posed about PVCs occurring with exercise I would consider doing a stress ECG to observe rhythm closely with a 12 lead medical grade ECG. You could also consider a Holter monitor or a 12 lead Holter monitor.
      Dr. P

  3. See my post on LinkedIn , interval correlation studies have already been done . QTc will be most useful and a Russian device , the EKG Dongle offers more diagnostic abilities .

  4. I bought the original Kardia and quickly diagnosed my afib that my cardiologist and other doctors missed. I even had gone to the er once and the machine said i had afib and the er and my cardiologist said it wasn’t afib, but two months later I had very clear afib. So far medication seems to be working with minimal side effects but dr recommended ablation already. Im thinking I need a new doctor. Anyway, I’m upgrading my Kardia but it wont be as easy to do the ecg’s at work with pants on lol.

  5. Looking forward to this.

    Hope there is a system whereby it can be stored with the iPhone carry case – I cut a rectangular hole in the iPhone case so the original Kardia with two terminal pads was piggybacked onto the phone, available at all times.Quite unobtrusive and slim in my pocket.

    But looking at the video, this might be hard to organise. Maybe an iPhone case with a wallet style pouch to keep the new Kardia on board.

    The convenience of the Kardia band, and AW4, means that a reading is instantly available, a great encouragement to use whenever symptoms are felt.

  6. Looking forward to the 6L. If it is anything like Kardia’s current product(s), it will be second to none. Get rid of that Apple Watch. Try for a refund, a lawsuit (class action) call me, or give to a family member or friend who already knows they are in permanent AFIB. Just kidding about that part. But GO KARDIA. THE BEST.


  7. I had a great deal of trouble with my single lead unit. Typical male: if at first something does not work – simply put more shoulder into it. I had to ‘lighen up’.

    Thanks for the tip on this Doc. I am lucky, I don’t really have issues, but like to stay ahead of things. Cheers.


  8. I am hoping not to need my single lead anymore after an apparently successful ablation. It was my single lead that confirmed my syncopal episodes and afib. I know that you are not a fan of ablation, but if it keeps me out of the ER it is well worth the risks.


Please leave your comments. The skeptical cardiologist loves feedback. He reads all and replies to all that warrant a reply.