Tag Archives: Kardia

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,

-ACP

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.

Enlightened Medical Management of Atrial Fibrillation: Part I. Amiodarone, Kardia And Cardioversions

The skeptical cardiologist is a firm believer in the benefit of maintaining normal rhythm in most patients who develop atrial fibrillation (AF, see here.)

Sometimes this can be accomplished by lifestyle changes (losing pounds and cutting back on alcohol , treating sleep apnea, etc.) but more often successful long term maintenance of normal rhythm (NSR) requires a judicious combination of medications and electrical cardioversions (ECV).

It is also greatly facilitated by a compliant and knowledgeable patient who is regularly self-monitoring with a personal ECG device.

My article on electrical cardioversion (see here)  was inspired by a patient (we’ll call her Sandy) who asked me  in April of 2016, “how many times can you shock the heart?”

In 2016 I performed her fifth cardioversion and last week I did her sixth.

Her story of AF is a common one which exemplifies how excellent medical management of AF can cure heart failure and mitral regurgitation and create decades of AF-free, happy and healthy existence.

A Tale Of Six Cardioversions

Sandy had her first episode of atrial fibrillation in 2001 and underwent a cardioversion at that time and as far as she knew had no AF problems for 14 years. I’ve seen numerous cases like this where following a cardioversion, patients maintain NSR for a long time without medications but I’ve also seen  many in whom AF came back in days to months.

In 2015 she saw her PCP for routine follow-up and AF with a rapid rate was detected.  She had been noticing shortness of breath on exertion and a cough at night but otherwise had no clue she was out of rhythm.

When I saw her in consultation she was in heart failure and her echocardiogram demonstrated a left ventricular  ejection fraction of 50% with severe mitral regurgitation.  She quickly went back into AF after an electrical cardioverson (ECV) and  reverted to AF again following a repeat ECV  after four days on amiodarone.

Since amiodarone can take months to reach effective levels in the heart we tried one more time to cardiovert after loading on higher dosage amiodarone for one month. This time she stayed in NSR

Following that cardioversion she has done extremely well. Her shortness of breath resolved and follow up echocardiograms have demonstrated resolution of her mitral regurgitation.

She had purchased a Kardia mobile ECG device for personal monitoring of her rhythm and we were able to monitor her rhythm using the KardiaPro dashboard. Recordings showed she was consistently maintaining NSR after her 2016 ECV

Image from my online KardiaPro Dashboard showing the date and HR of patient’s home ECG recordings leading up to the cardioversion and following it. The orange dots were Kardia diagnosed AF and following the cardioversion the green dots are NSR.

 

 

 

I’ve written extensively on the great value of KardiaPro used in conjunction with the Kardia mobile ECG device for monitoring patients pre and post cardioversion for atrial fibrillation.  Sandy  does a great job of making frequent Kardia ECG recordings, almost on a daily basis so even though she has no symptoms we are alerted to any AF within 24 hours of it happening.

Amiodarone-The Big Medical Gun For Stopping Atrial Fibrillation

The recurrence of AF Sandy had in 2016 occurred 8 months after I had lowered her amiodarone dosage to 100 mg daily.

Amiodarone is a unique drug in the AF toolkit.

It is the by far the most effective drug for maintaining sinus rhythm, an effect that makes it our most useful antiarrhythmic drug (AAD).

  1. It is cheap and well-tolerated.
  2. Uniquely among drugs that we use for controlling atrial fibrillation it takes a long time to build up in heart tissue and a long time to wear off.
  3. It is the safest antiarrhythmic drug from a cardiac standpoint. Unlike many of the other AADs we don’t have to worry about pro-arrhythmia (bringing out more dangerous rhythms such as ventricular tachycardia or ventricular fibrillation) with amio.
  4. Amiodarone, however, is not for all patients-it has significant long term side effects that necessitate constant vigilance by prescribing physicians including thyroid, liver and lung toxicity.

I monitor my patients on amiodarone with thyroid and liver blood tests every 4 months and a chest x-ray yearly and I try to utilize the minimal dosage that will keep them out of AF.

In Sandy’s case it was apparent that 100 mg was too little but with an increase back to 200 mg daily, the AF remained at bay.

In early 2017, Sandy read on Facebook that amio was a “poison” and after discussing risks and benefits we decided to lower the dosage to 200 mg alternating with 100 mg. It is common and appropriate for patients to be fearful of the potential long term and serious consequences of medications. For any patient taking amiodarone I always offer the option of stopping the drug with the understanding that there is a strong likelihood of recurrent AF within 3 months once the drug wears off.

In October, 2018 with Sandy continuing to show normal heart function and maintain SR as documented by her daily Kardia ECG tracings we decided to further lower the dosage to 100 mg daily.

Six months later she noted one day that her Kardia reading was showing a heart rate of 159 bpm and diagnosing atrial fibrillation. AF had recurred on the lower dosage of amiodarone.  She had no symptoms but based on prior experience we knew that soon she would go into heart failure.

Image from my online KardiaPro report on Sandy showing all green dots (NSR) until she went into AF (orange dots). Upon discharge from the hospital the daily Kardia recordings now show NSR (green dots).

Thus, her amiodarone was increased and a sixth cardioversion was performed. We could find no trigger for this episode (unless the  bloody mary she consumed at a  Mother’s Day Brunch 2 days prior was the culprit.)

Medical Management With Antiarrhythmics Versus Ablation

Many patients seek a “cure” for atrial fibrillation. They hear from friends and neighbors or the interweb of ablation or surgical procedures that promise this.  Stopafib.org, for example,  promotes these types of procedures saying “Catheter ablation and surgical maze procedures cure atrial fibrillation”

In my experience the majority of patients receiving ablation or surgical procedures (Maze procedure and its variants) ultimately end up having recurrent episodes of atrial fibrillation. Guidelines do not suggest that anticoagulants can be stopped in such patients. Often, they end up on AADs.

I’ve prepared a whole post on ablation for AF but the bottom line is that there is no evidence that ablation lowers the AF patient’s risk of dying, stroke, or bleeding. My post will dig deeper into the risks and benefits of ablation.

There is no cure for AF, surgical, catheter-based or medical.

In the right hands most patients can do very well with medical management combined with occasional cardioversion.

Who posseses the right hands?

In my opinion, most AF patients are best served by a cardiologist who has a special interest in atrial fibrillation and takes the time to read extensively and keep up with the latest developments and guideline recommendations in the area. This does not need to a be an electrophysiologist (EP doctor-one who specializes in the electrical abnormalities of the heart and performs ablations, pacemakers and defibrillators.)

I have a ton of respect for the EP doctors I work with and send patients to but I think that when it comes to doing invasive, risky procedures the decision should be based on a referral/recommendation from a cardiologist who is not doing the procedure.

In many areas of cardiology we are moving toward an interdisciplinary team of diagnosticians, interventionalists, surgeons and non-cardiac specialists to make decisions on performance of high-risk and high-cost but high-benefit procedures like valve repair and replacement, closure of PFOs and implantation of left atrial appendage closure devices.

It makes sense that decisions to perform high-risk , high-cost atrial fibrillation procedures also be determined by a multi-disciplinary team with members who don’t do the procedure.

This is a rule of thumb that can also be applied to many surgical procedures as well.  For example, the decision to proceed to surgical treatment of carotid artery blockages (carotid endarterectomy) is typically  made by the vascular surgeons who perform the procedure. In my opinion this decision should be made by a neurologist with expertise in neurovascular disease combined with a good cardiologist who has kept up with the latest studies on the risks and benefits of carotid surgery and is fully briefed on the latest guideline recommendations.

Unbenightedly Yours,

-ACP

A Guide To Using Apple Watch and Kardia ECG devices-What They Can and Can’t Do

Many patients (and perhaps physicians) are confused as to how best to utilize personal ECG devices. I received this question illustrating such confusion from a reader recently:

I first came across your website a year ago during persistent angina attacks, and returning now due to increasing episodes of symptoms akin to Afib. I bought a Kardia 2 yrs ago for the angina episodes, and looking to buy the Apple Series 4 for the Afib, as I want to try a wearable for more constant monitoring. What I would greatly appreciate if you had a basic guide for both the Kardia & Apple devices, specifically when and how to best employ them for unstable angina and detecting undiagnosed Afib. As in, what can I as a patient provide to you as a doctor for diagnosis in advance of a formal visit. I’m a US Iraq vet medically retired in the UK, and most of my concerns get dismissed out of hand as “anxiety”, not sure why they thought a stent would cure my anxiety though  

Personal, Wearable ECG Devices Won’t Diagnose Angina (or Heart Attacks)

First. please understand that none of these devices have any significant role in the management of angina. Angina, which is chest/arm/jaw discomfort due to a poor blood supply to the heart muscle cannot be reliably diagnosed by the single lead ECG recording provided by the Apple Watch, the Kardia Band or the Kardia mobile ECG device. Even a medical-grade 12 lead ECG doesn’t reliably diagnose angina and we rely on a constellation of factors from the patient’s history to advanced testing to determine how best to manage and diagnose angina.

Second, as you are having episodes “akin to Afib”, all of these devices can be helpful in determining what your cardiac rhythm is at the time of the episodes if they last long enough for you to make an ECG recording.

The single lead ECG recording you can make from the Apple Watch, the Kardia Band and from the Kardia mobile device can very reliably tell us what the cardiac rhythm was when you were feeling symptoms.

The algorithms of these devices do a good job of determining if the rhythm Is atrial fibrillation. Also, if the rhythm is totally normal they are good at determining normality.

However, sometimes extra or premature beats confuse the algorithms resulting in an unclassified tracing and (rarely) an inaccurate declaration of afib

These tracings can be reviewed by a competent cardiologist to sort out what the rhythm really is.

In all of these cases, having an actual recording of the cardiac rhythm at the time of symptoms is immensely helpful to your doctor or cardiologist in determining what is causing your problems.

My recommendation, therefore, would be to make several recordings at the time of your symptoms. Print them out and carefully label the print-out with exactly what you were feeling when it was recorded and present these to the doctor who will be reviewing your case.

As I’ve mentioned in previous posts (see here), my patients’ use of Kardia with the KardiaPro online service has in many cases taken the place of expensive and inconvenient long term monitoring devices.

Case Example-Diagnosing Rare And Brief Attacks Of Atrial Fibrillation

I recently saw a patient who I think perfectly demonstrates how useful these devices can be for clarifying what is causing intermittent episodes of palpitations-irregular, pounding, or racing heart beats.

She was lying on a sofa one day when she suddenly noted her heart “pumping fast” and with irregularity. The symptoms last for about an hour. She had noticed this occurred about once a year occurring out of the blue.

Her PCP ordered a long term monitor, a stress test and an echocardiogram.

The monitor showed some brief episodes of what I would term atrial tachycardia but not atrial fibrillation but the patient did not experience one of her once per year hour long episodes of racing heart during the recording. Thus, we had not yet solved the mystery of the prolonged bouts of racing heart.

She was referred to me for evaluation and I recommended she purchase an Alivecor device and sign up for the KardiaPro service which allows me to view all of her recordings online. The combination of the device plus one year of the KardiaPro service costs $120.

She purchased the device and made some occasional recordings when she felt fine and we documented that these were identified as normal by Kardia. For months nothing else happened.

Then one day in April she had her typical prolonged symptom of a racing heart and she made the recording below (She was actually away from home but had the Kardia device with her.)

When she called the office I logged into my KardiaPro account and pulled up her recordings and lo and behold the Kardia device was correct and she was in atrial fibrillation at a rate of 113 BPM.

With the puzzle of her palpitations solved we could now address proper treatment.

Continuous Monitoring for Abnormal Rhythms

Finally, let’s discuss the wearables ability to serve as a monitor and alert a patient when they are in an abnormal rhythm but free of any symptoms.

My reader’s intent was to acquire a device for “constant monitoring”:

I’m looking to buy the Apple Series 4 for the Afib, as I want to try a wearable for more constant monitoring.

This capability is theoretically available with Apple Watch 4’s ECG and with the Kardia Band (using SmartRhythm) which works with Apple Watch Series 1-3.

However, I have not been impressed with Apple Watch’s accuracy in this area (see here and here) and would not at this point rely solely on any device to reliably alert patients to silent or asymptomatic atrial fibrillation.

In theory, all wearables that track heart rate and alert the wearer if the resting heart rates goes above 100 BPM have the capability of detecting atrial fibrillation. If you receive an alert of high HR from a non ECG-capable wearable you can then record an ECG with the Kardia mobile ECG to see if it really is atrial fibrillation.

At 99$, the Kardia is the most cost-effective way of confirming atrial fibrillation for consumers.

I hope this post adds some clarity to the often confusing field of personal and wearable ECG devices.

Electroanatomically Yours,

-ACP

Can The Apple Watch Or Kardia ECG Monitor Detect Heart Attacks?

The skeptical cardiologist recently received this email from a reader:

With the new Apple Watch that’s out now, people have suggested my husband (who had a heart attack at 36) should get it since it could detect a heart attack. But I keep remembering what you said – that these devices can’t detect heart attacks and that Afib isn’t related to a heart attack most of the time – is that still the case? I don’t really know how to explain to people that it can’t do this, since absolutely everyone believes it does.

The answer is a resounding and unequivocal NO!

If we are using the term heart attack to mean what doctors call a myocardial infarction (MI) there should be no expectation that any wearable or consumer ECG product can reliably diagnose a heart attack.

The Apple Watch even in its latest incarnation and with the ECG feature and with rhythm monitoring activated is incapable of detecting a myocardial infarction.

Similarly, although the AliveCor Kardia ECG monitor is superb at diagnosing rhythm abnormalities it is not capable of detecting an MI

To make this even clearer note that when you record an ECG on the Apple Watch it intermittently flashes the following warning:

 

Note: “Apple Watch never checks for heart attacks”

How did such this idea take root in the consciousness of so many Americans?

Perhaps this article in 9-5 Mac had something to do with it

The article begins
Scott Killian never imagined his Apple Watch might save his life, but that’s exactly what happened a few weeks ago when he had a heart attack in the middle of the night. Killian recently shared his personal experience with 9to5Mac, and the details of his story are absolutely amazing.
In reality,  the man received an alarm that his resting heart rate was high at night. Apparently he also was experiencing chest pain and went to an ER where a cardiac enzyme was elevated.  Subsequently he underwent testing that revealed advanced coronary artery disease and he had a bypass operation. 
Even if we assume all the details of this story are accurate it is absolutely not a case of Apple Watch diagnosing an MI.
 
A high resting heart rate is not neccessarily an indicator of an MI and most MIs are not characterized by high heart rates.  We have had the technology with wearables to monitor resting heart rate for some time and no one has ever suggested this can be used to detect MI.
 
The rate of false alarms is so high and the rate of failure to diagnose MI so low that this is a useless measure and should not provide any patient reassurance.
 
The writer of this story and the editors at 9-5 Mac should be ashamed of this misinformation.
 
Several other news sources have needlessly muddied the water on this question including Healthline and Fox News:
 
 
 
 
 
 
 
The Fox News article entitled “Could The Apple Watch Series 4 save you from a heart attack” quotes a non-physician who suggests that AW can detect early signs of a heart attack:
 

In clear cut cases the Apple Watch could make the difference between life and death,” says Roger Kay, president of Endpoint Technologies Associates. Because you wear the Apple Watch at all times, it can detect an early sign of a stroke or a heart attack, and that early indication is critical, he says.

And the Healthline article on the new Apple Watch also incorrectly implies it can diagnose MI:

The device, which was unveiled last week, has an electrocardiogram (ECG) app that can detect often overlooked heart abnormalities that could lead to a heart attack.

And if you are felled by a heart problem, the fall detector built into the Apple Watch Series 4 could alert medical professionals that you need help

Fox News and Healthline should modify their published articles to correct the misinformation they have previously provided.

And it is still true that  although both Apple Watch and Kardia can diagnose atrial fibrillation the vast majority of the time acute heart attacks are not associated with atrial fibrillation.

Readers, please spread the word far and wide to friends and family-Apple Watch cannot detect heart attacks!

Skeptically Yours,

-ACP

Putting The Apple Watch 4 ECG To The Test In Atrial Fibrillation: An Informal Comparison To Kardia

My first patient this morning, a delightful tech-savvy septagenarian with persistent atrial fibrillation told me she had been monitoring her rhythm for the last few days using her Apple Watch 4’s built in ECG device.

Previously she had been using what I consider the Gold Standard for personal ECG monitoring- AliveCor’s Kardia Mobile ECG   and I monitored her recordings through our Kardia Pro connection.

I had been eagerly awaiting Apple’s roll out since I purchased the AW4 in September (see here) and between patients this morning I down-loaded and installed the required iPhone and Watch upgrades and began making AW4 recordings.

Through the day I tried the AW4 and the Kardia on patients in my office.

Apple Watch 4 ECG Is Easy and Straightforward

The AW4 ECG recording process is very easy and straightforward. Upon opening the watch app you are prompted to open the health app on your iPhone to allow connection to the Watch ECG information. After this, to initiate a recording simply open the Watch ECG app and hold your finger on the crown.

Immediately a red ECG tracing begins along with a 30 second countdown.

Helpful advice to pass the time appears below the timer:

“Try Not to move your arms.”

and

“Apple Watch never checks for heart attacks.”

When finished you will see what I and my patient (who mostly stays in sinus rhythm with the aid of flecainide) saw-a declaration of normality:

Later in the day I had a few patients with permanent  atrial fibrillation put on my watch.

This seventy-something farmer from Bowling Green, Missouri was easily able to make a very good ECG recording with minimal instruction

The AW4 nailed the diagnosis as atrial fibrillation.

We also recorded a Kardia device ECG on him and with a little more instruction the device also diagnosed atrial fibrillation

After you’ve made an AW4 recording you can view the PDF of the ECG in the Health app on your iPhone where all of your ECGs are stored. The PDF can be exported to email (to your doctor) or other apps.

ECG of the Bowling Green farmer. I am not in afib.

Apple Watch Often “Inconclusive”

The AW4 could not diagnose another patient with permanent atrial fibrillation and judged the recording “inconclusive”

The Kardia device and algorithm despite a fairly noisy tracing was able to correctly diagnose atrial fibrillation in this same patient.

I put the AW4 on Sandy, our outstanding echo tech at Winghaven who is known to have a left bundle branch block but remains in normal rhythm and obtained this inconclusive report .

Kardia, on the other hand got the diagnosis correctly:

One Bizarre Tracing by the AW4

In another patient , an 87 year old lady with a totally normal recording by the Kardia device, the AW4 yielded a bizarre tracing which resembled ventricular tachycardia:

Despite adjustments to her finger position and watch position, I could not obtain a reasonble tracing with the AW4.

The Kardia tracing is fine, no artifact whatsoever.

What can we conclude after today’s adventures with the Apple Watch ECG?

This is an amazingly easy, convenient and straightforward method for recording a single channel ECG.

I love the idea that I can record an ECG whereverI am with minimal fuss. Since I wear my AW4 almost all the time I don’t have to think about bringing a device with me (although for a while I had the Kardia attached to iPhone case that ultimately became cumbersome.)

Based on my limited sample size today, however, the AW4 has a high rate of being uncertain about diagnoses. Only 2/3 cases of permanent atrial fibrillation were identified (compared to 3/3 for the Kardia) and only 4/6 cases of sinus rhythm were identified.

If those numbers hold up with larger numbers, the AW4 is inferior to the Kardia ECG device.

I’d rather see the AW4 declare inconclusive than to declare atrial fibrillation when it’s not present but this lack of certainty detracts from its value.

What caused the bizarre artifact and inconclusive AW4 tracing in my patient is unclear. If anybody has an answer, let me know.

We definitely need more data and more studies on the overall sensitivity and specificity of the AW4 and hopefully these will be rapidly forthcoming.

For most of my patients the advantages of the AW4 (assuming they don’t already have one) will be outweighed by its much greater cost and we will continue to primarily utilize the Kardia device which will also allow me to view all of their recordings instantaneously in the cloud.

Conclusively Yours,

-ACP

Note. The original version of this post had the wrong ECG tracing for the first “inconclusive” AW4 recording of a patient with permanent atrial fibrillation. H/t to discerning reader Vignesh for pointing this out months after the initial posting.

A Review Of The QardioCore ECG Strap From A Patient’s Perspective

One of my patients has been on the cutting edge of personal cardiac monitoring devices and I asked him to share his recent experience with the QardioCore ECG strap. What he sent me is a fascinating description of how the device works (which is unique in this area) along with how it was crucial in diagnosing the cause of his recent symptoms. I’m sharing it below.


I’m a current patient of the Skeptical Cardiologist and have experienced recovery from 14 months of Atrial Fibrillation with Rapid Ventricular Response, and subsequent heart failure.   While I haven’t had symptoms of heart failure or Atrial Fibrillation in over 6 months, as a former long-distance cyclist, I had been following the progress for the FDA approval of the QardioCore device since it was announced over a year ago.   You can learn more about their device at https://www.getqardio.com/qardiocore-wearable-ecg-ekg-monitor-iphone/, but I’ve pasted text from their website here: (https://support.getqardio.com/hc/en-us/articles/115000257105-Electrocardiogram-ECG-EKG- )

“QardioCore is a clinical-quality wearable electrocardiogram recorder. An electrocardiogram – often abbreviated as ECG or EKG – is a test that measures the electrical activity of the heart. With each heart beat, an electrical impulse (or “wave”) travels through the heart. This wave causes the muscle to squeeze and pump blood from the heart.

 

An ECG gives two major kinds of information. First, by measuring time intervals on the ECG, a doctor can determine how long the electrical wave takes to pass through the heart. Finding out how long the wave takes to travel from one part of the heart to the next shows if the electrical activity is normal or slow, fast or irregular. Second, by measuring the amount of electrical activity passing through the heart muscle, a cardiologist may be able to find out if parts of the heart are too large or are overworked. During an ECG, several sensors, called electrodes, capture the electrical activity of the heart.

QardioCore is ideal for health conscious individuals or those with known or suspected heart conditions to record their everyday ECGs, physical activity, sport performance and medical symptoms and share their data with their doctors. Medical professionals can use QardioCore to quickly assess heart rate and rhythm, screen for arrhythmias, and remotely monitor and manage patients who use QardioCore.

 

QardioCore should be only used in conjunction with professional medical advice, diagnosis, or treatment, and not as a substitute, or a replacement for it. Qardio creates products and services that conform to US quality, safety and security requirements for medical products, while delivering a modern user experience. QardioCore will begin selling in the US after receiving US Food and Drug Administration clearance.”

Unfortunately, the US FDA tends to move slowly, and we can only speculate as too why, but the device is not available for purchase here.   However, I found a friend in France who purchased one for me and shipped me the device.   It is not illegal for me to use the device here, but it is not allowed to be sold here in the US.

I use an Apple I-Phone 8Plus and have used both the AliveCor KardiaBand and the KardiaMobile found here (https://store.alivecor.com), and reviewed by the esteemed Skeptical Cardiologist in other posts as well.   While I find it as a useful tool, my only dissatisfaction is that I want to passively monitor my heart during sporting activities and look for rhythm disturbances.   While I’m no expert in either sporting activities or rhythm disturbances, I’ve completed some healthy reading and living on both subjects and have a general awareness of the topic.

The QardioCore device is simple to wear, comes with three belts that can be used and cleaned, and comes with a charging cable.   Everything that the app, and the product does, seems to be accurately described on their web site, so I won’t cover off on details here.   You can read more about it at this link:   https://www.getqardio.com/qardioapp/   My only dissatisfaction with this device, and other blue tooth devices, has nothing to do with the device itself.   Apple seems to randomly disconnect from Bluetooth devices with their phones.   I don’t pretend to know the specific mechanisms for the problem, but my blue tooth devices for bicycling, music headsets, and heart monitoring have all been plagued with intermittent blue tooth connection problems.   So, at times, I find myself having to restart their app to keep the device connected, which is a minor annoyance.   

I also use the QardioArm product to measure and monitor my blood pressure and am satisfied with it as well.

What follows is my anecdotal experiences of September 26, 2018 through the present day and I agreed to write about them here, in case it provides useful insight to others in some way.

As a person with a short-term history of heart problems, I tend to capture a lot of data with my devices.   I monitor things like heart rate variability, blood pressure, Alivecor Kardia readings, sleep history, etc.   I make an active attempt to monitor my levels of stress, but I know for certain that I lead a stressful life.  I work longer hours than I should, probably sleep less than I should, exercise less than I like and should, and medicate and pray far less than I should.  So, I don’t want to imply that anything that happened is the fault of the medical system, bad blue tooth connections, bad medical care, or bad advice from the Skeptical Cardiologist or any other medical professional.   I tend to listen well, learn well, but I don’t always act as I should.  But, I’m responsible for my choices, my decisions, and I live with the results of my actions.

With that said, I was sitting at the office on Wednesday September 26th, 2018 and was working away without a care in the world.   As a computer programmer, I’m very sedentary and enjoy my work.   I was wearing my QardioCore ECG strap at the time because I’m a big believer in capturing baseline data for my general living and lifestyle.   I believe this data was invaluable in my first episode of heart problems, but have no supporting evidence to support my claim.   At around 8:58:42 AM, I felt somewhat bad, and felt my heart racing.   I glanced over at my phone which was showing the ECG trace at the time and noticed what I believed was Atrial Flutter at the time.   But, after about 20 seconds, the ECG trace returned to normal, and I felt fine again.   I made a quick note of the time, because I was busy, and continued working for the day.  The Quardio App provides no diagnostic information, so it doesn’t analyze and interpret ECG patterns like the Alivecor Kardia app does. When I arrived at home later that day, I went back to look at the ECG trace, as the Quardio App easily allows that through features of the App.   When I found the point in time of the ECG, I became concerned immediately because I believe that I was seeing a pattern that I recognized as Ventricular Tachycardia, a condition that comes in many forms, and has many causes, but can be fatal if not properly treated.   As my cortisol levels increased, I contacted Dr. Google and just quickly verified that I wasn’t completely nuts, although I acknowledge there may be some partial nuttiness there.   While going through this process, I experienced another 4 second episode which only increased my anxiety levels.   After contacting my wife and asking her to return home, and informing some family members, I felt it best that I should contact the Skeptical Cardiologist after hours for input on my problem.   I hate to bother the doctor, as he is a busy man, but contacted his after-hours number.  While the operator on the other end of the line wondered what kind of nut case I was, she kindly contacted the doctor who promptly called me on my cell phone.    I had informed the kind doctor that I had the device about three weeks prior, so he was already aware that I had the QardioCore.   I quickly informed the doctor that I believed I had experienced at least one but possibly two cardiac events.   After briefly talking, I hung up the phone and texted him photos of the screens from the Quardio App, so he could see the ECG tracings.   Here are the photos that I sent to the Skeptical Cardiologist via text:

 

 

IMG_6828

 

IMG_6829

I believe this tool is valuable in many ways, but I believe that it was helpful for the Skeptical Cardiologist, as it helped narrow our focus of blood tests, scans, and potential procedures to run in a faster than normal basis.   Normally, if I had not had evidence (accurate or not), I would have had to schedule an appointment, or go to ER.   At that point, they would have either ordered an event monitor for me to wear while I was away from the hospital, or they would have had to admit me.   Since I had a past history of Atrial Fibrillation, which isn’t quite as serious, we would have been sent home with an event monitor and instructions to take it easy and continue to take meds.   We would have run more blood work, and more scans, but the point is that we would have been more broadly focused, as we would have had to generally guess as to the nature of the event and narrow it down.

I recognize that this is one of the controversies that is active in clinical cardiology, as I listen to podcasts by Dr. John Mandrola and others regarding the latest cardio devices, procedures and research.   I realize that many Cardiologists are not in favor of devices like these, because they lead to uninformed conclusions, which leads to unneeded stress on both patients and their stressed-out doctors and cardiologists.   I’ve listened to both sides of the argument, and I have my own opinions that I won’t express here.   I will just say that I believe that this device saved me time, possibly my life (as I don’t know what I don’t know, unless I know to look), and some time in hastening and narrowing my therapy choices.

I will say that my wife and I were extremely happy with the services provided by his staff, himself, his colleagues, and the hospital staff as well.   While I am confident I may be considered a difficult patient by some, or many, they were very thorough and kind in their treatment and explanation of my treatment options.

I hope that my experience adds helpful insight to the discussion.   I’m confident that the Skeptical Cardiologist will add to this post, with his views on the events I’ve discussed above.   And, I believe he appreciates having a Skeptical Patient every now and then as well.


As The Skeptical Patient wrote,  this device is not sold in the United States. Having seen it in action now, I’m eager to get my hands on one and evaluate it further. It could dramatically alter home arrhythmia monitoring. For this patient it was incredibly helpful.  If any of my European or Australian readers has experience with it please let me know.

Qardio makes a stylish, accurate and portable home BP monitor that I’ve written favorably about here.

Qardiodynamically Yours,

-ACP

N.B. Featured image of man running on beach with QardioCore is not of my patient.

Apple’s Alternative Facts And The Giant Watch Restaurant Next Door To AliveCor

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.

Specifically, Gundotra says that his company was confused by Apple’s claims that the Series 4 will be the first over-the-counter ECG testing device for consumers. AliveCor is a 49-employee startup that makes over-the-counter ECG testing devices and software, including an FDA-cleared band for the Apple Watch, called KardiaBand, and a version that attaches to a smartphone, called Kardia.

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,”

Antialternafactively Yours,

-ACP

The New Apple Watch 4: Cardiac Accuracy Unknown, “Game-Changing” Benefits Overblown

On February 10, 2014 AliveCor, Inc. announced that its heavily validated personal  mobile ECG monitor had received FDA over-the counter clearance. Previously the device, which allows recording of a single-lead ECG and, in conjunction with a free smart-phone app, can diagnose atrial fibrillation was only available by prescription.

Since 2013, I have been successfully using this device with my patients who have atrial fibrillation (and writing about it extensively)

Apple COO Jeff Williams standing in front of (presumably) an ECG obtained by Apple Watch 4. It’s OK quality (but smallish p waves). Is that the best they could do? Notice that it is making a diagnosis of sinus rhythm. This PDF can be mailed “to your doctor.”

I was shocked, therefore, to hear the COO of Apple, Jeff Williams, announce that Apple will be offering in its new Apple Watch 4  “the first ECG product offered over the counter directly to consumers.”

This seemed blatantly inaccurate as AliveCor’s device clearly preceded by 4 years Apple’s claim.

Furthermore, AliveCor’s Kardia Band which converts any Apple Watch into a single-lead ECG  (which I’ve written about here and here) has been available and providing the Apple Watch-based ECGs since November 30, 2017.

AliveCor has an outstanding website which documents in detail all the research studies done on their products (there are dozens and dozens of linked papers) and all of their press releases dating back to 2012. It also explains in detail how the product works.

The title of their November 30, 2017 release was  FDA Clears First Medical Device Accessory for Apple Watch®

AliveCor shortly thereafter (December 12, 2017) announced Smart Rhythm , an Apple Watch app that monitors your rhythm and alerts you if it thinks you are in atrial fibrillation. I’ve discussed Smart Rhythm here.

Apple’s Watch will tell you that you are not in atrial fibrillation. Given that we don’t know how accurate it is, should that be reassuring?

The new Apple Watch’s rhythm monitoring app sounds a lot like Smart Rhythm but without any of the documentation AliveCor has provided.

So, within 10 months of Alivecor providing the world with the first ever wearable ECG (and proven its accuracy in afib) Apple seems to have come out with a remarkably similar product.

The major difference between Apple and AliveCor is the total lack of any reviewable data on the accuracy of the Apple device. Yes, that’s right Apple has provided no studies and no data and we have no idea how accurate its ECG device is (or its monitoring algorithm).

For all we know, it could diagnose sinus rhythm with frequent APCS or PVCs consistently as atrial fibrillation, sending thousands of Watch 4 wearers into a panic and overloading the health care system with meaningless alerts.

Apple’s website claims

Apple Watch Series 4 is capable of generating an ECG similar to a single-lead electrocardiogram. It’s a momentous achievement for a wearable device that can provide critical real-time data for doctors and peace of mind for you.

Apple’s “momentous achievement” was actually achieved 10 months earlier by AliveCor and if its monitoring algorithm and ECG system are significantly worse than the proven AliveCor system they will be destroying the peace of mind of users.

Electrodes built into the Digital Crown and the sapphire back crystal allow sensing of cardiac electrical signals. Did Apple get this idea from AliveCor?

After describing the Apple Watch’s new health features, Jeff Williams introduced Ivor Benjamin, MD, the President of the American Heart Association. Benjamin proceeded to describe the new Apple Watch cardiac features as “game-changing”, noting that the AHA is committed to helping patients be “proactive.”

Does  Benjamin have access to the accuracy of the Apple Watch ECG sensor? If so, he and the AHA should immediately share it with the scientific community. If not, by endorsing this feature of the Watch he should be ashamed. Users need to know if he or the AHA was paid any money for this appearance. Also, we should demand to know if (as the prominent AHA logo suggested and news reports implied) the AHA is somehow endorsing the Apple Watch.

Frequent readers know I’m a huge Apple fan but this Apple Watch business makes me think something is rotten in the state of Apple.

Skeptically Yours,

-ACP

AliveCor Mobile ECG : Ways To Minimize Low Voltage and Unclassified Recordings

Sometimes AliveCor’s Mobile ECG device yields unclassified interpretations of recordings. Understandably if you want to know whether your rhythm is normal or atrial fibrillation, the unclassified  classification can be very frustrating.

There are various caues of an unclassified tracing with different solutions.  Some unclassified recordings are due to a heart rate over 100 BPM or under 50 BPM and cannot be fixed. Similarly, some patients with ectopic beats like PVCS may consistently generate unclassified interpretations (see my discussion here).

Artifacts induced by poor recording techniques are common as a cause and almost always can be fixed.

These can be reduced by minimizing motion, extraneous noise, and maximizing contact with the electrodes.  Follow all the steps AliveCor lists here.

For me, the following step is crucial

  • If your fingers are dry, try moistening them with antibacterial wipes or a bit of lotion

And be aware the device needs to be near the microphone of your iPad or smartphone.

Low Voltage As Cause of Unclassified Kardia Recordings

Another cause of unclassified interpretations is a low voltage recording (which I initially discussed here.).

At the recent ACC meeting I asked Alivecor inventor and CEO David  Albert if he had any solutions to offer for those who obtain unclassified low voltage AliveCor tracings.

He told me that the cause is often a vertically oriented heart and that recording using the lead II technique can often solve the problem.

Lead II involves putting one electrode on your left knee and one your right fingers as described in this video:

Reader “J”  recently sent me a series of Kardia ECG recordings,  some of which were unclassified , some normal and one read as possible atrial fibrillation.

The unclassified and possible AF tracings looked like this:

 

They were very regular with a rate between 80 and 100 BPM but they totally lacked p waves. It was not clear to me what the rhythm was on these tracings.

Other tracings had lowish voltage but the p waves were  clearly visible  and Kardia easily classified them as normal

Lowish voltage with p waves (Type B)

 

Good QRS voltage with clear p waves ( Type B

 

Still others had improved QRS voltage with clear p waves and were also classified  appropriately as normal

 

After some back and forth emails we discovered that the ECG recordings with no p waves were always  made using the chest lead recording.   AliveCor-describes this as follows:

  • For an Anterior Precordial Lead, the device can be placed on the lower left side of the chest, just below the pectoral muscle. The bottom of the smartphone or tablet should be pointing towards the center of the body.

Mystery solved!

There is an abnormal cardiac rhythm that is regular between 80 and 100 BPM with no p waves and normal QRS called junctional tachycardia but in J’s case the absent p waves are related to the recording site.

Also, note that for this young woman the lead II voltage (Type B tracing) is much higher than the standard, lead I voltage (type A tracing).

Lead II With Pants On

After Dr. Albert told me of the advantages of Lead II I responded that it seemed somewhat awkward to take one’s pants off in order to make an ECG recording.

He immediately reached in his suit pocket and pulled out a pen-shaped device and began spraying a liquid on his left knee.

To my surprise he was able to make a perfect Lead II recording without taking his pants off!

Lessons learned from reader J and Dr. A:

  • Consider trying different leads if the standard Lead I (left hand, right hand) is consistently yielding unclassified ECG recordings
  • Try Lead II (left knee, right hand) to improve voltage and recording quality
  • You can record off your knee even with your pants on if you are prepared to spray liquids on your pants

Pantsonically Yours,

-ACP

Kardia’s Fascinating SmartRhythm For Apple Watch Is Very Cool: Will It Allow Personal Atrial Fibrillation Detection?

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

SmartRhythm display. The light blue vertical bars representing heart rate range during an interval. The continuous lines above and below the vertical bars show the boundaries of heart rate predicted by the neural network based on your measured activity from the Watch accelerometer. . Upper left corner is yellow triangle indicating that the system detected potential abnormal rhythm and recommended a recording. The dot on the right is an ECG recording. The vertical bars at the very bottom represent steps taken during an interval

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.

The Apple Watch face of my patient with the Kardia icon bottom right. Note also that she has a Starbucks reward available

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.

Fastidiously Yours,

-ACP

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!

Three hearts showing a P-Wave, QRS-Complex, and a T-Wave

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.