Tag Archives: AF

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.

Why Did I Go Into Atrial Fibrillation?

The skeptical cardiologist is asked this  question or  variations of it (such as  what caused me to go out of rhythm?) on a daily basis.

Most patients would like to have a reason for why their atria suddenly decided to fibrillate.  It’s understandable. If they could identify the reason perhaps they could stop it from happening again.

There are two variations on this question:

For the patient who has just been diagnosed with afib the question is really “what is the underlying reason for me developing this condition?”

For the patient who has had afib for a while and it comes and goes seemingly randomly the question is “what caused the afib at this time? i.e. what triggers my episodes?”

For most patients, there is no straighforward and simple answer to either one of these questions

The Underlying Cause of Atrial Fibrillation

My stock response to this first question goes like this:

“Atrial fibrillation is associated with getting older and having high blood pressure. 10 % of individual >/= 80 years have atrial fibrillation. 90% of patients with afib have hypertension.

Aging and hypertension may increase scarring or damage in the left atrium or pulmonary veins that drain into the left atrium setting up abnormal electrical signals.

There are some specific things that cause afib and we will be doing a complete history and physical and some testing to check for the most common. We’ll check you for thyroid or electrolyte abnormalities and we will do an echocardiogram to look for any structural problems with your heart.

If we do find a treatable cause such as hyperthyroidism or a cardiac valve problem we will fix that and the afib may go away, however chances are we won’t find a specific reason why you developed atrial fibrillation.

Finally, and possibly most importantly, let’s take a close look at your lifestyle. Are you overweight? If so, losing 10% of your body weight will substantially lower your risk of recurrent atrial fibrillation. Let’s get you exercising regularly and eating a healthy diet, Make sure your sleep is optimized and your stress minimized.”

If you’d like a more sophisticated look into what causes afib take a look at this graphic from a recent paper.

Current theory has it that factors that we know are associated with atrial fibrillation  including obesity, hypertension and sleep apnea cause atrial structural abnormalities or remodeling which then create various atrial electrical abnormalities.

 

Exhaustive List of Causes

If you’d like an exhaustive list of factors associated with atrial fibrillation, you can memorize the acronym P.I.R.A.T.E.S. which is sometimes used by medical students to remember the causes of atrial fibrillation which include:

  • Pulmonary disease (COPD, PE)/Phaeochromocytoma
  • Ischemia (ACS)
  • Rheumatic heart disease (mitral stenosis)
  • Anemia (high output failure/tachycardia)/Atrial myxoma/Acid-base disturbance
  • Thyrotoxicosis (tachycardia)
  • Ethanol/Endocarditis/Electrolyte disturbance (hypokalaemia, hypomagnesaemia)/Elevated BP
  • Sepsis/Sick Sinus Syndrome/Sympathomimetics (Drugs)

And here’s a cute  mnemonic from the Family Practice Notebook using ATRIAL FIB itself (although you have to use the ph of pheochromocytoma to make the f of fib)

  1. Alcohol Abuse
  2. Thyroid Disease
  3. Rheumatic Heart Disease
  4. Ischemic Heart Disease
  5. Atrial Myxoma
  6. Lung (Pulmonary Embolism, Emphysema)
  7. Pheochromocytoma
  8. Idiopathic
  9. Blood Pressure (Hypertension)

Both of these mnemonics are a little outdated. For example, rheumatic mitral stenosis is quite rare as a cause of afib in the US but  degenerative and functional mitral regurgitation is a common cause.

Ischemic heart disease (aka coronary heart disease) isn’t felt to cause atrial fibrillation unless it results in a myocardial infarction and subsequent heart failure. Way too many cardiac catheterizations are performed on patients who present with atrial fibrillation by doctors who don’t know this.

Congenital heart defects (not mentioned in either mnemonic) especially atrial septal defects often are associated with afib

There may be case reports of pheochromocytoma (a catecholamine-secreting neuroendocrine tumor) causing afib but they are few and far between.

Finally, genetics clearly play a role in the younger patient with afib without any known risk factors. One of my patients and his twin brother both developed symptomatic afib in their 40s.

In The Chronic Afibber What Triggers An Episode?

Alas, for most afibbers we won’t identify specific reasons why you go in and out of afib although there are some triggers you should definitely avoid such as excessive alcohol.

Some of the “causes” listed in the mnemonic are acute triggers of afib episodes.

For example low potassium or magnesium (typically induced by diuretics, diarrhea or vomiting) can bring on episodes .(See my discussion on potassium and PVCS here-much of it is relevant to afib.)

And I  have definitely seen patients go  into atrial fibrillation who have acute pulmonary problems such as pneumonia, pulmonary embolism or exacerbation of COPD.  In these cases, it is felt that the lung process raises pressure in the pulmonary arteries thereby  putting strain on the right heart leading to higher right atrial pressures.

Sleep apnea is associated with afib and I have had a few cases where after identifying that a patient’s  afib always began during sleep we were able to substantially lower episodes by treatment of sleep apnea.

Pericarditis with inflammation adjacent to the left atrium not uncommonly causes  afib. This is the likely mechanism for the afib that occurs frequently after cardiac surgery. Since pericarditis may never recur (especially in the cardiac surgery patient) we think the risk of afib recurring is low in these patients.

Anything that raises stress and stimulates the sympathomimetic nervous system can be a trigger. For example, a young and otherwise healthy patient of mine went into afib after encountering a car in flames along the side of the road. We found that beta-blockers (which block the sympathetic nervous system) helped prevent her episodes.

Some patients have odd but reproducible triggers. One of my patients routinely went into afib when he ate ice cream. I had a simple , very effective treatment plan for him.

Caffeine and Chocolate

Many afibbers have been told to avoid caffeine but a recent study of 34,000 women found that there was no increased risk of afib with increasing caffeine content and no sign that any of the individual contributors to caffeine in the diet (coffee, tea, cola, and chocolate) were more likely to cause afib.

Higher chocolate consumption, in fact, has recently been linked to a lower rate of afib. An observational  study of 55 thousand Danish men and women found that those who consumed 2 to 6 servings per week of 1 oz (30 grams) of chocolate had a 20% lower rate of clinically apparent afib.

Alcohol and Atrial Fibrillation

Binge drinking has long been known to cause acute atrial fibrillation.

However, it appears that even light to moderate chronic alcohol consumption increases the risk of going into atrial fibrillation.

This graphic from an excellent recent review of the topic gives the potential mechanisms:

The review concludes that although light to moderate alcohol consumption lowers your risk of dying, any alcohol consumption increases your risk of afib.

This graph shows the relationship between dying from heart disease (red line) and risk of going into afib (blue line) and amount of alcohol consumed.

Looking at the 15 drinks per week point on the x-axis (about 2 drinks per day) we see that your CV mortality is reduced by 20% whereas your risk of afib has increased by 20%.

A better point on the x-axis is 7 (1 drink per day) which has a 25% lower CV mortality but only a 10% higher risk of afib.

Whatever caused you to go into afib the good news is that with lifestyle changes and the care of a good cardiologist chances are excellent that you can live a normal, happy, healthy , long and active life.

Etiologically Yours,

ACP

 

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

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

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.

 

 

They Were in Normal Sinus Rhythm for Halloween

The skeptical cardiologist likes to see his afib patients stay in the normal rhythm (normal sinus rhythm) after they are cardioverted. On Halloween here in the office at Cardiac Specialists of St. Lukes three of our assistants helped drive home the message with a creative ensemble costume:

img_7951
Three marvelous medical assistants  help maintain normal sinus rhythm and battle the chaos of atrial fibrillation. (From left to right, Trish, Diane, and Jenny)

Speaking of Halloween, rather than handing out candy next Halloween, I’ll be handing out sacks of stroke-bustin’ nuts.

I’m sure the neighborhood kids will love the alternative to all that high fructose corn syrup!

Frightfully Yours

-ACP

 

 

 

Atrial Fibrillation Ablation: Time For A Team Approach?

For many proceduralists in medicine and surgery, there is a tendency to overestimate the value and underestimate the risk of the intervention that they perform. This factor, plus the current medical reimbursement system in the US, which rewards physicians primarily on the quantity of services performed rather than the quality of care, fosters a strong incentive for proceduralists to perform their procedures early and often.

It is rare for a proceduralist to publicly advocate a cautious and circumspect approach to their procedure; the usual public expressions are highly enthusiastic endorsements intended for marketing and increasing volume.

In this regard, it is particularly refreshing to read the thoughts today of a clinical electrophysiologist, whose bread and butter partially consists of doing ablations of atrial fibrillation (AF.)

John Mandrola (who writes a great blog at DrjohnM.org and reports for theheart.org) has written an excellent summary of the things that patients should consider prior to getting an AF ablation which I shall reblog below.

Mandrola asks us to consider whether the decision for AF ablation should be made by a team rather than by the proceduralist who stands to benefit from performing the ablation.

I’ve emphasized some points from his post:

-AF ablation is a multi-hour procedure that requires general anesthesia. Up to 80 burns are made in the left atrium, some close to the esophagus and phrenic nerve. There are significant risks to the procedure. The honest long-term success rate barely tops 50%.

-Many patients have to undergo a second procedure, or even third or fourth procedures.

-Some questions an AF team might ask:

  • Have you checked the patient for sleep apnea?

  • Have you asked him to reduce his alcohol intake or weight?

  • Will the AF resolve after the stress of a divorce has worn off?

  • Does the patient know there’s not a shred of evidence that AF ablation reduces stroke or death rates?

 

-Does the patient know that AF is not deadly heart disease? In other words, has fear been sufficiently extracted from the decision?

I, not infrequently, refer appropriate patients to excellent and thoughtful electrophysiologists for a discussion of the pros and cons of ablation and consideration of its performance .  Before sending them, I try to act like the “team” that Mandrola envisions and review the risks and benefits along with alternative approaches.

Below is John’s post in its entirety:

A patient presents with atrial fibrillation (AF) and a rapid rate. He doesn’t know he is in AF; all he knows is that he is short of breath and weak.

The doctors do the normal stuff. He is treated with drugs to slow the rate and undergoes cardioversion. During the hospital stay, he receives a stress test and an implantable loop recorder.

He goes home on a couple of medications. The expensive implanted monitor shows rare episodes of short-lived AF, less than 1% of the time. The patient feels great.

But here’s the kicker: his doctor recommends an AF ablation.

This is nuts. The man has had one episode of AF. He has no underlying heart disease. And he feels well while taking only basic meds. There’s been no discussion of weight loss, exercise, alcohol reduction, or sleep evaluation.

I don’t know how often this happens in the real world, but I suspect that it’s happening more and more. The number of doctors trained in electrophysiology have increased. And, trainees in academic centers spend most of their time mastering the AF ablation procedure.

The Dartmouth Atlas of Healthcare group have shown cardiology to be a supply-sensitive service. Meaning, the more cardiologists there are in an area, the more procedures get done. This build-it-and-they-will-come problem dogs much of US healthcare, not only cardiology. Think MRI and CT centers.

Might a solution to the overuse of AF ablation be a multi-disciplinary heart team?

We already do this for some heart valve surgeries, specifically, transaortic valve replacement (TAVR).

AF ablation is a multi-hour procedure that requires general anesthesia. Up to 80 burns are made in the left atrium, some close to the esophagus and phrenic nerve. There are significant risks to the procedure. The honest long-term success rate barely tops 50%. (Success rates depend somewhat on the type of AF.)

Then there are the repeat procedures. Many patients have to undergo a second procedure, or even third or fourth procedures. (All at many thousands of dollars per case.)

If doctors recommending the procedure had to present the patient to a team of peers, there may be more discussion about the sobering realities of AF care. Questions could arise:

  • Have you checked the patient for sleep apnea?
  • Have you asked him to reduce his alcohol intake or weight?
  • Will the AF resolve after the stress of a divorce has worn off?
  • Does the patient know there’s not a shred of evidence that AF ablation reduces stroke or death rates?
  • Does the patient know that AF is not deadly heart disease? In other words, has fear been sufficiently extracted from the decision?

I recognize that not every decision in medicine should be made by committee. AF ablation, however, might fit some sort of internal review.

The European Heart Journal just published a terrific review on the treatment of persistent AF. In this paper, the treatment of risk factors gets strong mention–as does the sobering results of AF ablation in more advanced forms of AF, and the vast uncertainty surrounding treatment approaches.

I’m not against AF ablation; I perform the procedure often. But after I’m sure all other aspects of atrial-health have been addressed, and the patient is fully informed. It’s a huge mistake to equate AF ablation with ablation of other focal (emphasis on focal) rhythm problems, like supraventricular tachycardia.

I’d have no trouble justifying my AF ablation procedures to a heart team.

JMM

Can Ovine Obesity (Fat Sheep) Teach Us About Atrial Fibrillation?

Until the last year or so when patients asked me what they could do to help their atrial fibrillation (AF) I would tell them to avoid excessive alcohol consumption and take their medications as prescribed.

My response has changed because new data suggest that losing weight and exercising can significantly reduce the recurrent rate of atrial fibrillation. Now, in addition to my standard reasons for staying at ideal body weight and exercising regularly I can toss in the fact that atrial fibrillation will be less frequent and troublesome.

I had noted previously that the majority of my patient’s with AF were obese and sedentary (although there are definitely many AF patients who exercise regularly, eat a great diet and stay at their ideal body weight0 but data was lacking to suggest cause and effect.

LAAfat
View of the left atrial appendage (LAA) and posterior aspect of left atrium obtained in a 400 pound woman about to undergo  electrical cardioversion for her atrial fibrillation. The orange arrow points to extensive collection of fat in the walls of the atrium.

In addition, I had noted that when I looked at the left atrium of the vast majority of patients with AF using an imaging tool called trans-esophageal echocardiography they had evidence for fatty infiltration into the area between the atria (atrial septum)  and the wall of the left atrium.

I strongly suspected based on these observations that somehow the fat infiltrating into the walls of the left atrium was triggering AF but I had no way of proving it.  Isolated observations like these can only generate hypotheses on causality.

Science has many different approaches to solidifying or proving hypotheses and one such approach is to induce a disease in an animal similar to humans and make detailed analyses of the cause and consequences.

Australian researchers writing in JACC in July present their observations on the electrical, physiologic and structural changes that result when sheep get fat.

How Do You Make Sheep Fat?

Apparently you just let them eat as many pellets made of energy-dense soybean oil (2.2%) and molasses–fortified grain as they want.

After 36 weeks the 10 sheep given ad libitum pellets weighed twice as much as the sheep who were restricted and kept lean

After 36 more weeks of obesity the sheep were studied extensively. All sheep underwent “electrophysiological and electroanatomic mapping; hemodynamic and imaging assessment (echocardiography and dual-energy x-ray absorptiometry); and histology and molecular evaluation”.

The investigators found

“Sustained obesity results in global biatrial endocardial remodeling characterized by LA enlargement, conduction abnormalities, fractionated electrograms, increased profibrotic TGF-β1 expression, interstitial atrial fibrosis, and increased propensity for AF. Obesity was associated with reduced posterior LA endocardial voltage and infiltration of contiguous posterior LA muscle by epicardial fat, representing a unique substrate for AF”

The fat sheep developed AF and had multiple abnormalities in the left atrium, the source of AF, that made them more likely to develop atrial fibrillation.
Screen Shot 2015-09-01 at 4.32.32 PM In fact, the investigators believe it was fat collecting around the heart and specifically around the posterior left atrium that was triggering all these changes.

The pictures to the left show a heart from one of the fat sheep. The arrow points to the extensive amount of fat collecting posterior to the left atrium.

When the posterior left atrial wall was viewed microscopically, fat cells could be seen infiltrating between the muscle cells in the fat sheep (right, blue arrow) but not in the lean sheep. Screen Shot 2015-09-01 at 4.33.06 PM

In the fat sheep, fat cells (adipocytes)  were enlarged and infiltrated between the muscle cells of the left atrium, presumably disrupting the normal electrical activity and contributing to the development of atrial fibrillation.

More Reasons To Stay At Your Ideal Body Weight!

If you were previously unmotivated to avoid obesity perhaps this will motivate you.

Think about fat cells gathering around your heart and pouring their evil humours into the tissues of your left atrium and making it more likely that you will develop AF. With AF comes increase risk of stroke, heart failure and death.

-unadipocytically yours

-ACP

AliveCor Smartphone App Detects Atrial fibrillation: Potential for Stroke Prevention

Atrial fibrillation (AF)  is a common abnormal rhythm of the heart which causes 1 in 4 strokes. Those afflicted with AF may lack any symptoms or only have a vague sense of irregularity of their heartbeat and thus the first symptom of AF can be stroke.

The gold standard for diagnosing AF has long been the electrocardiogram (ECG or EKG) and typically the ECG involves placing 12 electrodes on the chest/arm/legs and recording the electrical activity of the heart on an expensive device.

I’ve been checking out a device made by Alive Cor which works with your smart phone to record a single channel ECG and is capable of accurately diagnosing if you are in the normal (sinus) rhythm or in AF.
Screen Shot 2015-07-12 at 8.45.49 AMYou can purchase the third generation (significantly smaller then earlier versions) AliveCor Mobile ECG from Amazon or from AliveCor directly for 74.99$ and it works with an app with both iOS and Android devices.

I used mine with my iPhone 6. At first I carried it separately, fearing the added bulk when stuck on to my iPhone case but after a while I realized that it was never with me when I wanted to use it and that there was a huge risk of losing it and so I used the backing adhesive to attach it to my case.

After pairing the device with the app you put two fingers on each of the metal pads and the smartphone screen displays the recording. After 30 seconds of recording it then interprets the rhythm.

Screen Shot 2015-07-12 at 8.56.47 AM
Typical recording in normal sinus rhythm. The red arrow indicates the small p waves which are the electrical signal of the upper chambers (the atria) depolarizing , the blue arrow indicates the electrical depolarization of the ventricles (QRS). The orange arrow indicates that the time interval between the QRS complexes is the nearly the same for each beat, indicating the regularity that we expect when in NSR compared to AF.

Above is a typical recording I made in my office on a patient who had a history of AF. The quality is good and I can clearly see that he is in normal sinus rhythm. The app correctly made the diagnosis of NSR and calculated his heart rate at 68 beats per minute.

One day I had most of my patients record their ECG’s using AliveCor and compared it to the standard 12-lead ECG we normally record. The device correctly identified the two patients with AF out of this group and correctly identified the normals.

Screen Shot 2015-07-12 at 9.26.42 AM
AliveCor recording of patient with AF with heart rate of 70 beats per minute. Note the absence of p waves before the QRS complexes and note the beat to beat variation in the RR interval (orange arrow)

This recording is from a patient with persistent AF which had recurred two weeks earlier. The device correctly identified AF.

Studies have documented that AliveCor Mobile ECG can accurately diagnose AF in a screening setting and the FDA approved the device for AF screening in 2014.

Given the high prevalence of silent AF, the strong association of AF with stroke and the availability of anticoagulants which reduce AF associated stroke by 70%, screening for AF with devices like AliveCor holds the promise of preventing large numbers of stroke.

(For my comments on taking the pulse and stroke prevention see here and on the inadvisability of a routine 12-lead ECG see here)

AliveCor allows physicians utilizing the Mobile APP and ECG to have a “dashboard” into which their patients can transmit their AliveCor ECG recordings.

I will be discussing this remarkable new device with my AF patients  who are smartphone enabled. I think it will advance our ability to more efficiently and quickly diagnose AF in them.

My standard approach if a patient with AF calls and says that they feel like they are out of rhythm is to have them come into the office for a full 12-lead ECG. If they are AliveCor enabled, they could make their own recording, and we could review that remotely and make a diagnosis without the office visit.

Let me know your thoughts on smartphone ECGs.

fibrillatorily yours,

-ACP