Category Archives: Medical/Fitness Devices

AfibAlert Versus AliveCor/Kardia: Which Mobile ECG Device Is Best At Accurately Identifying Atrial Fibrillation?

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.

Normal/Normal

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.

Chaput AFA SR

ACK recording was good quality but its algorithm could not classify the rhythm.

GC Unclassified

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 NSRChaput AFA SR

AliveCor/Kardia recordings on the same patient despite considerable and prolonged efforts to improve the recording were poor and were classified as “unreadable”

Scott AC unreadable
Alivecor tracing shows wildly varying baseline with poor definition of p wave

 

False Positives

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.

VA AFA read as AF
Slight irregularity of rhythm combined with a wider than normal QRS from right bundle branch block and poor recording of p waves likely caused AFA to call this afib
VA unclassified RBBB
AliveCor tracing calls this unclassified. The algorithm does not attempt to classify patients like this with widened QRS complexes due to bundle branch block.

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.IMG_8399.jpg

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.

Screen Shot 2017-05-06 at 11.48.47 AM
These are recordings Lawrence made at home that i can pull up on my computer. He makes a daily recording which he repeats if he is diagnosed with atrial fibrillation. In the two cases above of AF a repeat measurement was read as normal. Of the two cases which were unclassified , one was normal with APCs and the other was actually atrial flutter

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.

Screen Shot 2017-05-06 at 11.47.37 AM

Sure enough, when I recorded his rhythm with ACK although NSR (with APCS) it was read as unclassified

Screen Shot 2017-05-06 at 11.49.49 AM

AFA classified Lawrence’s rhythm as AF when it was in fact normal sinus with APCs.

AFA Mcgill AF

 

 

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 AFScreen Shot 2017-05-06 at 8.39.06 AMScreen Shot 2017-05-06 at 8.11.53 AM

In one 90 year old man AFA could not make the diagnosis (yellow)

Screen Shot 2017-05-06 at 11.35.40 AM

ACK correctly identified the rhythm as AF

Screen Shot 2017-05-06 at 11.37.51 AM

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>

Screen Shot 2017-05-06 at 8.42.46 AMScreen Shot 2017-05-06 at 8.42.26 AM

 

 

Overall Accuracy

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.

Summary

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.

-ACP

QardioArm: Stylish, Accurate and Portable. Is It the iPhone of Home Blood Pressure Monitors?

The skeptical cardiologist frequently has his hypertensive patients check their BPs at home and report the values to him.

An easy, accurate and efficient way to record BPs at home, and transmit to the doctor, is my Holy Grail for management of hypertension; QardioArm offers to improve on this process compared to more conventional home BP cuffs.

I recently bought a QardioArm for my father and tested one myself over the last month, and herein are my findings. I compared it closely to my prior “go to”  BP device, the Omron 10 (which I recommended as a Christmas gift here).

Appearance

The QardioArm looks like and is packaged like an Apple product. The box containing the device is esthetically pleasing, and can serve as an excellent storage and transportation mechanism. The case closes magnetically and has a pocket, within which resides the manual.

 

Upon removing the QardioArm, one is struck by how compact, sleek and cool it looks. This is not your father’s BP cuff. There are no wires or tubes coming off it, and the cuff wraps around a red (white, blue or gold) plastic rectangular cuboid.

The cuff/cuboid is small enough to easily fit in a purse or satchel, facilitating portability.

Ease of Use

Once you understand how the device works it is a breeze to use.  However, if you are inclined, like me, to skip reading the instruction manual, you run the risk of being incredibly frustrated.

First, you must download the free Qardio App to your smartphone, create a user login, register and create your personal account. If you don’t have a smartphone or tablet or don’t use the internet, this cuff if not for you. For me, this was a simple, quick process.

After setting up the Qardio App, you pair the QardioArm with the App. This requires the QardioArm be on and Blue Tooth be enabled on your smartphone.

An example of the profoundly negative review individuals give the device when they have not figured out the on/off process. This one on Consumer Reports

You might think that turning on the QardioArm, and knowing it is on,
would be an incredibly easy and obvious process: it is not (unless you pay close attention to the instructions). If you read reviews of Qardioarm on Consumer Reports or Amazon, you will encounter many very unhappy users. This is primarily because some folks could not get it to turn on.


Here are my detailed instructions for turning it on:

  1. There is a small magnet inside the cuff.
  2. The device turns itself on when you unwrap the cuff and it turns off when you wrap the cuff back up. (I am not good at wrapping things up properly and ran into issues initially because of this). When you wrap the cuff up properly you can feel the magnet locking into place and thus turning the device off.
  3. When the device is on there is no light to indicate it is on. A green light flashes on the side when it turns on, but then goes out. Many user reviews indicate frustration with this and often they end up trying to change the batteries, believing that the device is dead. I went through this same thought process initially.
  4. The device turns off “after a few minutes” if not used. You won’t know if it is on or off. If it doesn’t respond when you trigger it from the App, you must carefully rewrap the cuff and then unwrap it. If you don’t trigger the device properly with the magnet, it won’t wake up.

The QardioArm encircling the beautiful arm of the eternal fiancee’ of the skeptical cardiologist. Note: when the cuff is wrapped around my unattractive arm, it fastens properly and does not hang down.

Now that you know how to turn the device on and have paired it with your Cardio App, put the cuff over your upper arm with the cuboid over the inner aspect of your arm,
hit the big green START button and sit back while the cuff is magically inflated and an oscillometric measurement of your blood pressure performed.

 

 

The blood pressure is displayed on the app instantaneously along with pulse. If the device detects irregularity of the pulse (a possible but not reliable sign of atrial fibrillation or other abnormal heart rhythms), it display an “irregular heart beat” warning.

You can have the QardioArm take 3 BPs, a variable amount of time apart, and average the readings.

BP and pulse data can be viewed in tabular or graphic formats and  can be synched with the Apple Health App:

 

Accuracy

I found the QardioArm BP measurements to be very accurate. My medical assistant, Jenny, recorded our patient’s BPs using the “gold-standard” manual technique, and with QardioArm (consecutively and in the same arm), and there was excellent agreement. In one man with a very large arm, she could not record a BP (QardioArm’s cuff fits the arm of most people, and is appropriate for use by adults with an upper arm size between 22 and 37 cm (8.7 and 14.6 inches).  If your upper arm is larger than that, this device is not for you.  In one patient who was in atrial fibrillation, the device properly recorded an “irregular heart beat.”

From the Qardio website:

QardioArm is a highly accurate blood pressure monitor and has undergone independent, formal clinical validation according to ANSI/AAMI/ISO 81060-1:2007, ANSI/AAMI/ISO 81060-2:2009, ANSI/AAMI/IEC 80601-2-30:2009, as well as British Standard EN 1060-4:2004.

QardioArm is a regulated medical device: FDA cleared, European CE marked and Canadian CE marked.

It measures blood pressure with a resolution of 1 mmHg and pulse with 1 beat/min.

The accuracy is +/- 3 mmHg or 2% of readout value for blood pressure, and +/- 5% of readout value for pulse.

Comparison To Omron 10

I spent time evaluating the accuracy of QardioArm because a few online reviewers suggest that it is highly inaccurate for them and Consumer Reports gives it a “poor” rating for accuracy.

Consumer Reports gave the QardioArm an astonishingly low score giving it lower marks than the Omron for Convenience, Accuracy and Comfort. It gave the QardioArm a Poor mark for accuracy. No details of their measurement data are available on the site.

I compared it to the Omron 10 (Consumer Reports highest-rated BP device), and found close agreement between the two.

Simultaneous BP using Omron (above) and QardioArm (left)


I took my own BP with the QardioArm on the left arm and the Omron 10 on the right arm. Multiple simultaneous measurements showed less than 3 mmHg difference in systolic blood pressure between the two.

Unlike Consumer Reports, I found QardioArm superior to the Omron 10 in several areas:

  1. QardioArm is faster. It took 30 seconds to complete a BP measurement, compared to 50 seconds for the Omron 10.
  2. BPs are immediately available on my iPhone with QardioArm, whereas a separate Bluetooth synching process is required for the Omron App. This process never works well for me, as the Omron fails to transmit measurements reliably.
  3. It is amazingly easy to transmit BPs via email to your doctor (or friends if so inclined).

Support

I found the QardioArm website to be very informative and helpful. The manual that comes with the device is very complete and you should definitely read it before using the device. I did not need telephone or email support services, so I can’t comment on those.

Overall Rating and a Caveat

Despite an initial frustration with QardioArm, I ended up really liking this device a lot. This sounds a little silly but the QardioArm improved the esthetic experience of home BP monitoring for me. Because it is compact, sleek and attractive, patients may be more likely to utilize it on a regular basis. In particular, I see it as something that you would be much more inclined to take with you for BP monitoring at work or on vacation.

I will be recommending  this to my tech-savvy, style-conscious patients who require home BP monitoring. Previously, this type of patient would bring in their smartphone and show me the accumulated data from their BP readings. With a QardioArm, they can easily email my office the data and we can have it scanned into their record.

My final caveat: the QardioArm I gave my father for his 91st birthday does not work on his arm. It works without a problem on the arms of his friends and relatives. I have no idea why, but fortunately QardioArm honored their 30 day 100% money-back no questions asked guarantee. I’ve asked him to give me his nonagenarian perspective on the QardioArm experience so I can share it in a future post.


Quriously Yours,

-ACP

How Well Does The AfibAlert Remote Hand-Held Automatic ECG Device Work For Detection of Atrial Fibrillation?

I’ve been evaluating the ability of a mobile hand-held ECG device called AfibAlert to detect atrial fibrillation for the last few weeks.

I found that the device made very reliable and consistent recordings of cardiac rhythm and did a reasonably good job of detecting atrial fibrillation (afib).

The device  came in a plastic case with a USB cable for uploading recordings and two metal bracelets which attach to electrodes and provide an alternative recording method.

The device itself is about 6 by 3 by 1 inch.

 

Recordings are made by placing your thumbs on the silver/siver chloride electrodes

After a few seconds the display in the center will give heart rate and after 45 seconds the
device will make a decision about your rhythm:

If it diagnoses normal sinus rhythm a green check appears and if it diagnoses  afib a red telephone appears.

If it is confused you get yellow circular arrows.

As the maker of the device explains:

Lohman Technologies’ patented algorithm analyzes the patient’s heartbeat and the appropriate icon illuminates to show what action is needed. AfibAlert’s® algorithm was validated against 51,000+ ECG strips from the MIT-BIH Atrial Fibrillation Database with known diagnosis. The Afib monitor’s results were excellent, with 94.6% accuracy in detecting the presence of arrhythmias. Each recording produces a 45-second diagnostic quality ECG rhythm strip

The device I tested does not allow you to immediately see the ECG tracing. The recordings are uploaded to a PC via USB cable and then can be viewed as a PDF document.

I made 17  recordings on patients in my office one day. The age range was 50 to 93 years and most  patients were able to rapidly and easily  grasp the device with thumbs appropriately positioned to make interpretable recordings.

Only 2/17  came back. yellow. In both cases, I repeated the recording and the device was able to make the correct diagnosis. Twice I got the yellow signal on an elderly, partially blind patient who had trouble keeping his thumb on the electrode.

In 15  cases of normal sinus rhythm the device correctly identified NSR.

In one case of atrial fibrillation the device correctly identified atrial fibrillation.

 

 

In one case of SR with
APCs the device
incorrectly identified afib

 

Overall the device correctly classified 88% of the tracings. This was superior to the device I normally utilize ( AliveCor/Kardia mobile ECG)  in head to head comparison (I’ll present this comparison in a subsequent post).

My bullet points on the AfibAlert device:

-5 stars for Ease of Recording

-5 stars for Quality of recording

In all cases that uploaded, the recordings were very clear and free of artifact. The device did not upload yellow signal events and I presume more artifact is present in these recordings.

-2 stars for Convenience.

I found the software and uploading to be very awkward and slow. The company indicates new software soon to be released along with the ability to interface directly with iPads or smartphones that hopefully will improve this factor.

The inability to instantaneously view the ECG tracings means I cannot use it in my office to screen patients for arrhythmias. However, if a patient is solely using it to determine if afib is present or absent, this information is available right away.

-3 stars for Accuracy.

It does a reasonable job of identifying the patient who is in normal rhythm versus one in atrial fibrillation.

However, like AliveCor and other devices which strictly look at the variability of the pulse, it can be easily fooled by premature beats, especially when they are frequent, and inappropriately classify these as afib resulting in false positives.

In addition, when afib rates are very slow and thus much less variable it is likely AfibAlert will incorrectly classify them as normal thus resulting in false negatives.

False Negatives and False Positives

False negatives result in delayed diagnosis of afib. Patients will be falsely reassured that their rhythm is normal when it is not.

False  positives result in needless anxiety and testing/treatment.

If afib monitoring devices are to be successful they have to have a very low frequency of both types of inaccuracy.

The solution to inaccuracy of interpretation, of course, is to have a cardiologist over-read the tracings.

AfibAlert recordings are available online for review by your personal physician after being uploaded. This requires your physician to have an account with AfibAlert. There is no capability for having the recordings over read by an online cardiologist for a charge.

As far as I can tell the device is only available for purchase in the US and only on the AfibAlert website.

Interestingly, you cannot purchase AfibAlert  without a prescription from a physician.

Why this is mandated for AfibAlert and not AliveCor is a mystery to me.

 

 

Alertly Yours,

-ACP

 

 

What Is The Cause of Low Voltage (Unreadable or Unclassified) AliveCor/Kardia Mobile ECG Recordings?

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

EKG-3
First tracing. Note the QRS complex (the large regular spikes) are 2 boxes high. Right in front of them is a little bump, the p wave indicating normal sinus rhythm

 

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:

EKG-4
Second tracing. Note the QRS spikes now are less than half of a box tall. There are no consistent p waves visible (unless one has a good imagination). The bumps after QRS spikes are T waves.

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.

Voltagophilistically Yours,

-ACP

 

 

 

 

Do NOT Rely on AF Detect Smartphone App To Diagnose Atrial fibrillation

I’m writing this brief post as a warning to any individuals who have purchased the  smartphone app AF Detect (screen shot below from Apple app store.) It is not a reliable detector of atrial fibrillation (AF).

screen-shot-2017-02-19-at-11-25-56-am

 

A patient of mine with AF recently  purchased this app unbeknownst to me. He  relied on its faulty information which  reassured hm he was not in AF when in fact he was in AF. Such misinformation has the potential to lead to dangerous delays in diagnosis.

There are multiple reviews on the Apple and Google app sites which confirm the total lack of reliability of this app to diagnose AF with screen-shot-2017-02-19-at-9-18-10-ammultiple instances of both failure to detect known AF and inappropriate diagnosis of AF when rhythm was not AF.

In the description of the app the company says the app will “transform you rmobile device into a personal heart rate monitor and atrial fibrillation detector”.

However after purchasing the app and before using it you see this disclaimer which img_8348states it is not to be used for any medical diagnosis.

 

 

 

 

 

 

I will be performing a more detailed analysis of this app’s performance in the future and contacting the FDA about the danger such inaccurate medical testing confers on victims.

In the meantime if you have any experience with this app or other apps claiming to detect AF reliably using detection of the pulse from finger application to the camera lens please share them with me (via email  DRP@theskepticalcardiologist.com or via comments below.)

-ACP

Sustained Atrial Fibrillation or Not: The Vagaries and Inaccuracies of AliveCor/Kardia and Computer Interpretation of ECG Rhythm

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 img_8322cardiologist 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:
screen-shot-2017-02-14-at-5-37-42-am
screen-shot-2017-02-14-at-5-43-51-am screen-shot-2017-02-14-at-5-41-41-am

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 againscreen-shot-2017-02-14-at-5-44-09-am 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.

sr-pvcs-with-annotations
This tracing clearly (to me) shows regular and similar upward deflections (red arrow, p waves) which are a similar distance from the QRS complexes which follow (QRS complexes). The green arrows point to irregular deflections due to noise which can confuse computer algorithms (and non-cardiologists.) The distance between the QRS complexes is very regular (black arrow, RR interval). Thus, this is clearly normal sinus rhythm (NSR). Later in the recording PVCs (green arrows) are noted occurring every other beat. The distance between the QRS complexes on either side of the PVC is still the same as two RR intervals. This is clearly ventricular bigeminy.

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!

Are you listening, IBM?

Do you copy, Watson?

-ACP

AliveCor Mobile ECG Update: Successes and Failures

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:Screen Shot 2016-06-17 at 12.40.07 PM

After a month of normal daily recordings, she suddenly began feeling very light headed and weak with a sensation that her heart was racing.

Screen Shot 2016-06-17 at 12.41.13 PMShe 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 Screen Shot 2016-06-17 at 12.46.52 PMher 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

Review Options

AliveCor/kardia users  have the option of having their recordings IMG_6936-1interpreted 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:Screen Shot 2016-06-18 at 11.32.26 AMAlthough 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.

AliveCor Failures

A young woman emailed me that her AliveCor device on several screen-shot-2016-11-27-at-5-18-23-amoccasions 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.”screen-shot-2016-11-27-at-5-35-05-am

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,

-ACP

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.

screen-shot-2016-11-25-at-6-00-14-amP.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.