Tag Archives: AF

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:

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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