Tag Archives: atrial fibrillation

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

My Top Four Practice-Changing Presentations From the ACC 2019 Meeting: From Alcohol To Aspirin

The ACC meetings in New Orleans have wrapped up and I must stop letting the good times roll.

In the areas I paid attention to I found these four presentations the most important:

1. After the historic back to back presentations of the Partner 3 and Evolut trials it is clear that catheter-based aortic valve replacement (TAVR) should be the preferred approach to most patients with severe symptomatic aortic stenosis.

Both TAVR valves (the baloon-expanded Edwards and the self-expanding Medtronic) proved superior to surgical AVR in terms of one year clinical outcomes.

2. The Alcohol-AF Trial. It is well known that binge alcohol consumption (holiday heart) can trigger atrial fibrillation (AF) and that observational studies show a higher incident of AF with higher amounts of alcohol consumption.

This trial was the first ever randomized controlled trial of alcohol abstinence in moderate drinkers with paroxysmal AF (minimum 2 episodes in the last 6 months) or persistent AF requiring cardioversion.

Participants consumed >/= 10 standard drinks per week and were randomized to abstinence or usual consumption.

They underwent comprehensive rhythm monitoring with implantable loop recorders or existing pacemakers and twice daily AliveCor monitoring for 6 months.

Abstinence prolonged AF-free survival by 37% (118 vs 86 days) and lowered the AF burden from 8.2% to 5.6%

AF related hospitalizations occurred in 9% of abstinence patients versus 20% of controls

Those in the abstinence arm also experienced improved symptom severity, weight loss and BP control.

This trial gives me precise numbers to present to my AF patients to show them how important eliminating alcohol consumption is if they want to have less AF episodes.

It further emphasizes the point that lifestyle changes (including weight loss, exercise and stress-reduction) can dramatically reduce the incidence of atrial fibrillation.

3. AUGUSTUS. This trial looked at two hugely important questions in patients who have both AF and recent acute coronary syndrome or PCI/stent. The trial was simultaneously published in the New England Journal of Medicine. The questions were:

Apixaban (Eliquis, one of the four newer oral anticoagulants (NOAC)) versus warfarin for patients with AF: which is safer for prevention of stroke related to AF?

Triple therapy with  low dose aspirin and clopidogrel plus warfarin/NOAC versus clopidogrel plus warfarin/NOAC: which is safer in preventing stent thrombosis without causing excess bleeding in patients with AF and recent stent?

Briefly, they found:

The NOAC apixaban patients compared to warfarin had a 31% reduction in bleeding and hospitalization. No difference in ischemic events.

Adding aspirin  increased bleeding by 89%. There was no difference in  ischemic events. (Major or clinically relevant nonmajor bleeding was noted in 10.5% of the patients receiving apixaban, as compared with 14.7% of those receiving a vitamin K antagonist (hazard ratio, 0.69; 95% confidence interval [CI], 0.58 to 0.81; P<0.001 for both noninferiority and superiority), and in 16.1% of the patients receiving aspirin, as compared with 9.0% of those receiving placebo (hazard ratio, 1.89; 95% CI, 1.59 to 2.24; P<0.001).)

This means that the dreaded “triple therapy”  after PCI in patients with AF with its huge bleeding risks no longer is needed.

It also further emphasizes that NOACs should be preferred over warfarin in most patients with AF.

The combination of choice now should be a NOAC like apixaban plus clopidogrel.

4. REDUCE-IT provided further evidence that icosapent ethyl (Vascepa) significantly reduces major cardiovascular events in patients with establshed CV disease on maximally tolerated statin therapy.

The results of the pirmary end point from the REDUCE-IT were presented at the AHA meeting last year and they were very persuasive. At the ACC, Deepak Bhatt presented data on reduction of total ischemic events from the study and they were equally impressive. Adding the pharmaceutical grade esterified form of EPA at 2 grams BID reduced first, second, third and fourth ischemic events in this high risk population.

The benefit was noted on all terciles of baseline triglyceride levels. Thus, the lowest tercile of 81 to 190 mg/dl benefitted as well as the highest tercile (250 to 1401).

Although I dread the costs, it’s time to start discussing adding Vascepa on to statin therapy in high risk ASCVD patients who have trigs>100 .

As I wrote previously I didn’t learn anything from the much ballyhooed and highly anticipated Apple Heart Study . It’s entirely possible more participants were harmed than helped by this study.

Philomathically Yours,

-ACP

Apple Heart Study: Despite The Ballyhoo, No Benefits Demonstrated, Harms Not Measured

The results of the Apple Heart Study, were presented this morning at the American College of Cardiology Scientific Sessions amid intense media scrutiny. The AHS is a “prospective, single arm pragmatic study” which had the primary objective of measuring the proportion of participants with an irregular pulse detected by the Apple Watch who turn out to have atrial fibrillation on subsequent ambulatory ECG patch monitoring.

 

I and over 400,000 other Apple Watch owners participated in the AH study by downloading the Apple Heart Study app and self-verifying our eligibility. 

My assessment is that we have learned little to nothing from the AHS that we didn’t already know. I’m also concerned that many patients suffered anxiety or unnecessary testing after being referred to urgent care centers, emergency departments, cardiologists or primary care providers and the results of these inappropriate referrals may never be determined.

Here is the study in a nutshell:

  1. Participants enrolled by submitting  information using the iPhone Heart Study app and none of their isubmitted nformation was verified.
  2. An irregular pulse notification was issued to 0.5% of participants who were then  contacted and asked to participate in a Telehealth visit with a doctor (who we will call Dr. Appleseed)
  3. Only 945 of the 2161 who received a pulse notification participated in the first study visit.
  4. Interestingly, Dr. Appleseed was empowered to send participants to the ER if they had symptoms (chest pain, shortness of breath, fainting/losing consciousness) It is not clear how many were sent to the ER and what their outcomes were but this flow diagram shows that 20 were excluded from further testing due to “emergent symptoms.”

  5. Another 174 participants were excluded after finding out at the first visit that they had a history of afib or aflutter and 90 due to current anticoagulant use (both of these factors were exclusion criteria which gives us an idea of how accurate the information was at the time of participant entry.)
  6. After all these exclusions only 658 ECG monitor patches were shipped to the participants of which only 450 were returned and analyzed.
  7. This means of the original 2161 participants who were notified of pulse irregularity, the study only reports data on 450 or 21%. Such a low rate of participation makes any conclusions from the study suspect.
  8. Of the 450 ECG patches analyzed only 34% were classified as having afib. Only 25% of this afib lasted longer than 24 hours.
  9. After the patch data was analyzed, patients had a second Telehealth visit with Dr. Appleseed who reviewed the findings with the patient. Per the initial published description of the methods of the AHS (see here) Dr. Appleseed  would tell the participant to head to the ER if certain abnormalities were found on the ECG.

Per the study description (apple heart study), Dr. Appleseed recommended a visit to the PCP for “AF or any other arrhythmia” detected by the patch:”

“If AF or any other arrhythmias have been detected in reviewing the ambulatory ECG monitor data, or if there are other non-urgent symptom identified by the study physician during the video visit that may need further clinical evaluation, the Study Telehealth Provider directs the participant to his or her primary health care provider”

At this point it seems likely that a lot of participants were instructed to go see their PCPs. Because as someone who looks at a lot of 2 week ambulatory ECG recordings I know that is the rare recording that does not show “other arrhythmias.”

Even more distressing is the call that participants would have received based on “the initial technical read:” I’m presuming this “technical read” was by a technician and not by a cardiologist. In my experience, many initial reads from long term monitors are inaccurate.

“If the initial technical read identifies abnormalities that require urgent attention (ventricular tachycardia or ventricular fibrillation, high-degree heart block, long pauses, or sustained and very rapid ventricular rates), then the participant is contacted immediately and directed to local emergency care or advised how to seek local emergency care.”

I wonder how many  ERs had AHS participants show up saying they had been told they had a life-threatening arrhythmia? How much down stream testing with possible invasive, life-threatening procedures such as cardiac catheterization were performed in response to these notifications?

Overall, these findings add nothing to previous studies using wearable PPG technology and they certainly don’t leave me with any confidence that the  Apple Watch is accurately automatically detecting atrial fibrillation.

Was more harm than good done by the Apple Heart Study?

We will never know. The strength of this study, the large number of easily recruited participants is also its Achilles heel. We don’t know that any information about the participants is correct and we don’t have any validated follow up of the outcomes. In particular, I’m concerned that we don’t know what happened to all of these individuals who were sent to various health care providers thinking there might be something seriously wrong. 

Perhaps Apple and Stanford need to review the first dictum of medicine: Primum Non Nocere, First Do No Harm.

Tachogramophobically Yours,

-ACP

Life’s Simple 7 And The Prevention Of Atrial Fibrillation

In 2010 the AHA came up with “Life’s Simple 7”-seven modifiable health behaviors and biological factors- as part of its 2020 impact goal to improve the cardiovascular health of all Americans by 20% while reducing deaths from cardiovascular disease (CVD) and stroke by 20%.

The seven factors (LS7) were smoking, body mass index [BMI], physical activity, diet, total cholesterol, blood pressure, and fasting blood glucose, Attainment of optimal LS7 status has been associated with a reduced incidence of coronary heart disease, stroke, and heart failure (HF).

A recent observationsl study found that high LS7 scores was associated with a lower risk of developing atrial fibrillation

Each individual component was categorized as poor, intermediate, or ideal according to the American Heart Association’s LS7 criteria.1 Ideal levels of health factors were: nonsmoker or quit >1 year ago; body mass index <25 kg/m2; blood pressure <120/80 mm Hg; total cholesterol <200 mg/dL; fasting blood glucose <100 mg/dL; ≥150 min/week of physical activity; and a healthy diet score (≥4 components). Study participants who were treated to target levels for hypercholesterolemia, hypertension, or diabetes mellitus were classified as intermediate for the respective health factor. An overall LS7 score ranging from 0 to 14 was calculated as the sum of the LS7 component scores (2 points for ideal, 1 point for intermediate, and 0 for poor). This score was classified as inadequate (0‐4), average (5‐9), or optimum (10‐14) cardiovascular health.

I found this figure from the paper particularly interesting

 

Notice that there is a substantially lower risk of AF with lower BMI , blood sugar and blood pressure  but no relationship between the diet score and AF risk.

Clearly if you can get and keep your body weight down (which improves  blood pressure and diabetes risk) you will be in a lower risk category for atrial fibrillation.

On the other hand, having a total cholesterol <200 mg/dl is not associated with lower  risk of AF and in fact having an ideal score on this parameter is associated with higher risk. A total cholesterol is really not something that is a good marker for CV health and should be eliminated from the Life’s Simple 7 goals.

Even more enlightening is the total lack of any association between “healthy” diet and atrial fibrillation.

The healthy diet score was calculated as the sum of the scores for each of 5 individual components: fruits and vegetables (≥4.5 cups per day), fish (≥2 3.5‐oz servings per week), fiber‐rich whole grains (≥3 1‐oz‐equivalent serving per day), sodium (<1500 mg/day), sugar‐sweetened beverages (≤450 kcal/week). The range is from 0 to 5, with a lower score being unhealthy.

Taken in conjunction with studies showing reduced AF recurrence after weight loss it seems very clear that the single best thing obese afib patients can do to prevent recurrence is lose weight.  And it doesn’t matter what diet they utilize to accomplish the weight loss.

Skeptically Yours,

-ACP

Apple Watch Fails To Notify Patient Of 3 Hour Episode Of Rapid Atrial Fibrillation

Apple claims that its Apple Watch can detect atrial fibrillation (AF) and appropriately notify the wearer when it suspects AF.

This claim comes with many caveats on their website:

Apparently it needs to record 5 instances of irregular heart beat characteristic of atrial fibrillation over at least 65 minutes before making the notification.

This feature utilizes the watch’s optical heart sensors, is available  in Apple Watch Series 1 or later and has nothing to do with the Apple Watch 4 ECG recording capability which I described in detail in my prior post.

Failure To Detect AF

A patient of mine with known persistent AF informed me yesterday that she had gone into AF and remained in it for nearly 3 hours with heart rates over 100 beats per minute and had received no notification. She confirmed the atrial fibrillation with both AW4 recordings and AliveCor Kardia recordings while she was in it.

The watch faithfully recorded sustained heart rates up to 140 BPM but never alerted her of this even though the rate was consistently over her high heart rate trigger of 100 BPM.

The patient had set up the watch appropriately to receive notifications of an irregular rhythm.

Reviewing her tracings from both the AW4 and the Kardia this was easily diagnosed AF with a rapid ventricular response.

What does Apple tell us about the accuracy of the Apple Watch AF notification algorithm? All we know is the unpublished , non peer-reviewed data they themselves collected and presented to the FDA.

From this link on their website Apple says:

In a study of 226 participants aged 22 years or older who had received an AFib notification while wearing Apple Watch and subsequently wore an electrocardiogram (ECG) patch for approximately 1 week, 41.6% (94/226) had AFib detected by ECG patch. During concurrent wear of Apple Watch and an ECG patch, 57/226 participants received an AFib notification. Of those, 78.9% (45/57) showed concordant AFib on the ECG patch and 98.2 % (56/57) showed AFib and other clinically relevant arrhythmias. These results demonstrate that, while in the majority of cases the notification will accurately represent the presence of AFib, in some instances, a notification may indicate the presence of an arrhythmia other than AFib. No serious device adverse effects were observed

This tells us that about 80% of notifications are likely to be Afib whereas 20% will not be Afib. It is unclear what the “other clinically relevant arrhythmias”  might be. If I had to guess I would suspect PVCS or PACS which are usually benign.

If 20% of the estimated 10 million Apple Watch wearers are getting false positive notifications of afib that means 2 million calls to doctor or visits to ERs that are not justified.  This could be a huge waste of resources.

Thus the specificity of the AF notification is 80%. The other important parameter is the sensivitiy. Of the cases of AF that last >65 minutes how many are detected by the app?

Apple doesn’t seem to have any data on that but this obvious case of rapid AF lasting for 3 hours does not give me much confidence in their AF detection algorithms.

They do have a lot of CYA statements indicating you should not rely on this for detection of AF:

It is not intended to provide a notification on every episode of irregular rhythm suggestive of AFib and the absence of a notification is not intended to indicate no disease process is present; rather the feature is intended to opportunistically surface a notification of possible AFib when sufficient data are available for analysis. These data are only captured when the user is still. Along with the user’s risk factors, the feature can be used to supplement the decision for AFib screening. The feature is not intended to replace traditional methods of diagnosis or treatment.

My patient took her iPhone and Apple Watch into her local Apple store to find out why her AF was not detected. She was told by an Apple employee that the Watch does not detect AF but will only notify her if her heart rate is extremely low or high. I had asked her to record what they told her about the problem.

As I’ve written previously (see here) the Apple Watch comes with excessive hype and minimal proof of its accuracy. I’m sure we are going to hear lots of stories about AF being detected by the Watch but we need some published, peer-reviewed data and we need to be very circumspect before embracing it as a reliable AF monitor.

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.

AliveCor’s Mobile ECG With Kardia Pro Is Eliminating Any Need For Short or Long Term Cadiac Monitors For Most of My Afib patients: A Tale of Four Cardioversions

I described in detail in March (see here) my early experience in utilizing AliveCor’s KardiaMobile ECG  device in conjunction with their Kardia Pro cloud service to monitor my patient’s with atrial fibrillation (afib). Since that post the majority of my new afib patients have acquired the Kardia device and use it regularly to help us monitor their afib.

This capability has revolutionized my management of atrial fibrillation. In those patients who choose to use AliveCor there is really no need for long-term monitors (Holter monitors, Zio patches, cardiac event monitors) and no need for patients to come to the office to get an ECG when they feel they have gone into afib.

When one of my Kardia Pro patients calls with symptoms or concern of afib, I quickly pull up their chart at Kardiapro.com and review their recordings to determine if they are in or out of rhythm. Most treatment decisions can then be handled over the phone without the need for ordering a monitor or an emergency room or office visit.

One 24 hour period will suffice to show how important KardiaPro is now to my management of my patients with afib

A Day In The Afib Life

Tuesdays I spend the day working in the heart station at my hospital. Typically, on these days I will supervise stress tests, read ECGs and echocardiograms, perform TEES and electrical cardioversions. On a recent Tuesday I had 3 patients scheduled for cardioversion of their atrial fibrillation.

The day before one of these patients called indicating that he suspected he had reverted back to normal rhythm (NSR) based on his Kardia readings. He had had a prior cardioversion after which we know (thanks to daily Kardia recordings) he reverted to afib in 5 days. Subsequently we had started him on flecainide, a drug for maintenance of NSR and scheduled him for the cardioversion.

Not uncommonly after starting flecainide patients will convert to NSR but if they don’t we  proceed to an electrical cardioversion.

I logged into KardiaPro and reviewed his dashboard and sure enough his last two ECGs showed sinus rhythm. I congratulated him on this and we canceled his cardioversion for the next day, saving the lab the time and expense of a cancellation the day of the procedure. The patient avoided much stress, time and inconvenience.

Screen Shot 2018-10-13 at 7.27.49 AM
ECG recordings showing the patient had transitioned from afib (bottom two panels) to NSR (top two panels) after starting flecainide.

It is important to note that in this patient there was no great jump in heart rate with afib compared to NSR. For many patients the rate is much higher with the development of afib and this is often detected by non ECG wearable monitors (like an Apple Watch.)  But for patients like this one, an ECG is the only way to know what the rhythm is.


A second patient with afib who had elected not to acquire an AliveCor ECG device showed up for his cardioversion on Tuesday and after evaluating his rhythm it was clear he had spontaneously reverted back to NSR.  Prior to my adoption of KardiaPro this was a common and scenario.


The third scheduled cardioversion of the day showed up in afib and we successfully cardioverted him back to NSR. I had not addressed utilizing AliveCor with him. Prior to the procedure he asked me about likely outcomes.

My standard response to this question is that we have a 99.9% success rate in converting patients back to NSR at the time of the cardioversion. However, I can’t predict how long you will stay in NSR after the cardioversion. NSR could last for 5 days or it could last for 5 years. Adding medications like flecainide or amiodarone can significantly reduce the risk of afib recurrence after cardioversion.

At this point he asked me “How do I know if I am in afib?” Whereas many afib patients immediately feel bad and are aware that they have gone out of rhythm, this man like many others was not aware.

Prior to AliveCor my answer would have been to check the pulse daily or look for evidence of high or irregular heart rates on BP monitors or fitness wearables. This scenario provided a wonderful opportunity to test the AliveCor’s accuracy at detecting AF in him. I pulled out my trusty AliveCor mobile ECG and prior to the cardioversion we made the recording below

img_0702.jpg

After the cardioversion we repeated the Alivecor recording and the rhythm (AliveCor’s interpretation) had changed from afib  to NSR.

Needless to say, this patient purchased a Kardia device the next day and since the cardioversion he’s made a daily recording which has confirmed NSR. I just logged into Kardia Pro and sure enough he made a recording last night and it showed NSR.


Later in the week I received a call from a patient I had electrically cardioverted a few days earlier. His Kardia device had detected that he had gone back into afib.

I logged into my Mac and saw his KardiaPro chart below.

Kardia Pro displays green dots corresponding to NSR and orange triangles corresponding to afib with 100% accuracy in this patient.

 

 

With perfect precision KardiaPro had verified NSR after the cardioversion lasting for 36 hours. For some reason after dinner the day after the cardioversion, the patient had  reverted back to afib. This knowledge greatly facilitates subsequent treatment and eliminates the need for in office ECGs and long term monitors.


Utilization of the Kardia device with the Kardia Pro monitoring service has proved for me to b a remarkable improvement in the management of patients with afib. Managing non Kardia afib patients feels like navigating a forest with a blindfold.

The improvement is so impressive that I find myself exclaiming to my assistant, Jenny, several times a week “How do other cardiologists intelligently care for afibbers without AliveCor?”

I have a few patients who balk at the 15$ per month charge for Kardia Pro and ask why the device and this monthly charge aren’t covered by insurance or Medicare. Given the dramatic reduction that I have noticed in my use of long-term monitors  as well as  office and ER visits in this population, CMS and third-party insurers would be wise to explore Kardia monitoring as a more cost-effective way of monitoring afib patients.

antifibrillatorily Yours

-ACP

N.B. I realize this post appears to be an unmitigated enthusiastic endorsement of a commercial product which is quite uncharacteristic for the skeptical cardiologist.

One might wonder if the skepcard is somehow biased or compensated for his endorsement of Kardia.

In all honesty, this sprung from my love of the device’s improvement in my afib management and I have received no payment, monetary or otherwise from AliveCor and I own none of their stock (and I’m not even sure if it is on the stock market.)

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

Update On The Kardia Band Apple Watch Accessory: Accuracy In Atrial Fibrillation Pre and Post Cardioversion

As I described here, the Kardia Band (KB) is an FDA-approved Apple Watch accessory available to the general public without a prescription which records a high quality single-lead ECG.

I’ve been using mine now for a while and can confirm the ease and accuracy of the ECG recordings it makes. I find recordings made with my Apple Watch/Kardia Band are reliably high quality with minimal artifact (unless I’m running on a treadmill.)

Once the 30 second recording is completed, the Kardia app on the Apple Watch takes about 5 seconds to process the information using an AI algorithm and then makes a determination of normal sinus rhythm (NSR), atrial fibrillation or unclassified.

 

 

The New Study

A study published in the June JACC examined the accuracy of  Alivecor’s Kardia Band in detecting atrial fibrillation (AF.)

In the JACC study, investigators from the Cleveland Clinic studied  100 consecutive patients presenting for cardioversion from AF with recordings made before  and after the procedure. KB interpretations were compared to 12 lead ECGS read by electrophysiologists.

KB interpretations  identified AF with  93% sensitivity and 84% specificity. Of the total 169 recordings, 34% were unclassified due to short recordings, low-amplitude p waves, and baseline artifacts.

The authors concluded that the KB algorithm for AF detection, when it is supported by a physician review can reliably differentiate AF from NSR.

(Of note the lead author on this study is on the advisory board of Alivecor the maker of the KB and AliveCor (AliveCor, Mountain View, CA) provided the Kardia Band monitors which were connected to an Apple Watch and paired via Bluetooth to a smartphone device for utilization in the study. AliveCor was not involved in the design, implementation, data analysis, or manuscript preparation of the study.)

My Updated Kardia Experience

I have found the standard Kardia device to be immensely helpful in the management of my afib patients before and after cardioversions (see my prior description here). The paper mentions that 8% of these pre-cardioversion patients showed up for the procedure in normal sinus rhythm, noting that

For each of these patients, the automated KB algorithm did not erroneously identify AF, and the physician interpretation of the KB recording correctly confirmed SR in each case.

Needless to say, it is better to find out a cardioversion is not needed before the patient shows up for the procedure. I would estimate this happens about 5-10% of the time in my practice.

The Kardia device or the KB is also really helpful post cardioversion. If the patient makes daily recordings (which I can review on Kardia Pro online) h/she and I know exactly how long sinus rhythm persisted before reverting back to AF.

This is important information which impacts future management decisions.

Kardia Band Versus Standard Kardia Device

None of my patients have purchased the Kardia Band most likely due to the cost and the fact that they don’t have an Apple Watch. If you have an Apple Watch and want to monitor your heart rhythm I think the KB is a good choice. Otherwise, the original AliveCor mobile ECG device continues to do a fantastic job (in conjunction with Kardia Pro, see here).

The combination of Kardia and Kardia Pro has substantially reduced my use of expensive and annoying long term monitors in my AF population.

In my next update on the KB I will share a reader’s real world description of the pros and cons of the KB (with Smart Rhythm monitoring) in a patient post cardioversion for AF.

Skeptically Yours

-ACP

Is It Safe To Consume Grapefruit If You Take The Blood Thinner Apixiban (Eliquis)?

A patient of mine with atrial fibrillation taking the blood thinner eliquis told me that she had eaten grapefruit for two days in a row and then developed a nose bleed. She had heard of the interaction between grapefruit and certain medications and wondered if this had caused her nose bleed.

I was unaware of any eliquis/grapefruit interaction but thought this was a remarkably astute observation and question and set about to research it properly.

Among other things, I discovered that some researchers believe the grapefruit-drug interaction to be a widespread , underreported and  highly significant problem while others feel it is overblown and a rare cause of clinically important side effects.

For those, who prefer not to delves into the gory details I give you the crux of what BMS/Pfizer, the makers of apixiban (Eliquis) told me and with which I agree:

When consumed in usual dietary volumes, grapefruit juice is considered a moderate inhibitor of CYP3A4. Therefore a dose adjustment of apixaban is not expected to be required.

In other words, although not formally studied, there is no evidence that apixiban levels are increased by moderate grapefruit juice ingestion to a degree that would cause significant bleeding complications.

Although multiple sites on the internet (including the unreliable Web MD) will tell you of a potentially dangerous interaction between grapefruit and apixiban this theoretical interaction has not proven clinically significant.

Interactively Yours,

-ACP

Below is the full text of the letter BMS sent me

Bristol-Myers Squibb and/or Pfizer have not conducted any studies evaluating the concomitant use of apixaban and grapefruit juice. The decision to prescribe apixaban in patients who are concomitantly taking grapefruit juice is a clinical decision for the treating physician based on the individual’s circumstances and inaccordance with the full prescribing information for apixaban.

While in vitro data indicates grapefruit juice can inhibit both cytochrome P450 (CYP) 3A4 and P-glycoprotein (P-gp), clinical evidence suggests that grapefruit juice mediated interactions would be primarily due to the inhibition of CYP3A4 and the contribution of P-gp inhibition may be limited.1, 2 When consumed in usual dietary volumes, grapefruit juice is considered a moderate inhibitor of CYP3A4.1 Therefore a dose adjustment of apixaban is not expected to be required.

Apixaban is eliminated from the body through multiple pathways, with approximately 25% of the administered dose recovered as metabolites. The main metabolic pathway for apixaban is through CYP3A4/5, with minor contributions from other CYP isoenzymes. Apixaban is also a substrate of transport proteins P-gp and breast cancer resistance protein.3

  1. [1]  Hanley MJ, Cancalon P, Widmer WW,et al. The effect of grapefruit juice on drug disposition. Expert Opin Drug Metab Toxicol. 2011; 7(3):267-286.
  2. [2]  Farkas DG and Greenblatt DJ. Influence of fruit juices on drug disposition: discrepancies between in vitro and clinical studies. Expert Opin Drug Metab Toxicol. 2008;4(4):381-393.
  3. [3]  Eliquis® (apixaban) Package Insert. Bristol-Myers Squibb Company, Princeton, NJ and Pfizer Inc, New York, NY