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.
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.
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.
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.
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.”
“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.
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.
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.
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
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.
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.
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.)
On February 10, 2014 AliveCor, Inc. announced that its heavily validated personalmobile 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)
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.
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.
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.
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.
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.
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.
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.
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
 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.
 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.
 Eliquis® (apixaban) Package Insert. Bristol-Myers Squibb Company, Princeton, NJ and Pfizer Inc, New York, NY
Sometimes AliveCor’s Mobile ECG device yields unclassified interpretations of recordings. Understandably if you want to know whether your rhythm is normal or atrial fibrillation, the unclassified classification can be very frustrating.
There are various caues of an unclassified tracing with different solutions. Some unclassified recordings are due to a heart rate over 100 BPM or under 50 BPM and cannot be fixed. Similarly, some patients with ectopic beats like PVCS may consistently generate unclassified interpretations (see my discussion here).
Artifacts induced by poor recording techniques are common as a cause and almost always can be fixed.
These can be reduced by minimizing motion, extraneous noise, and maximizing contact with the electrodes. Follow all the steps AliveCor lists here.
For me, the following step is crucial
If your fingers are dry, try moistening them with antibacterial wipes or a bit of lotion
And be aware the device needs to be near the microphone of your iPad or smartphone.
Low Voltage As Cause of Unclassified Kardia Recordings
Another cause of unclassified interpretations is a low voltage recording (which I initially discussed here.).
At the recent ACC meeting I asked Alivecor inventor and CEO David Albert if he had any solutions to offer for those who obtain unclassified low voltage AliveCor tracings.
He told me that the cause is often a vertically oriented heart and that recording using the lead II technique can often solve the problem.
Lead II involves putting one electrode on your left knee and one your right fingers as described in this video:
Reader “J” recently sent me a series of Kardia ECG recordings, some of which were unclassified , some normal and one read as possible atrial fibrillation.
The unclassified and possible AF tracings looked like this:
They were very regular with a rate between 80 and 100 BPM but they totally lacked p waves. It was not clear to me what the rhythm was on these tracings.
Other tracings had lowish voltage but the p waves were clearly visible and Kardia easily classified them as normal
Still others had improved QRS voltage with clear p waves and were also classified appropriately as normal
After some back and forth emails we discovered that the ECG recordings with no p waves were always made using the chest lead recording. AliveCor-describes this as follows:
For an Anterior Precordial Lead, the device can be placed on the lower left side of the chest, just below the pectoral muscle. The bottom of the smartphone or tablet should be pointing towards the center of the body.
There is an abnormal cardiac rhythm that is regular between 80 and 100 BPM with no p waves and normal QRS called junctional tachycardia but in J’s case the absent p waves are related to the recording site.
Also, note that for this young woman the lead II voltage (Type B tracing) is much higher than the standard, lead I voltage (type A tracing).
Lead II With Pants On
After Dr. Albert told me of the advantages of Lead II I responded that it seemed somewhat awkward to take one’s pants off in order to make an ECG recording.
He immediately reached in his suit pocket and pulled out a pen-shaped device and began spraying a liquid on his left knee.
To my surprise he was able to make a perfect Lead II recording without taking his pants off!
Lessons learned from reader J and Dr. A:
Consider trying different leads if the standard Lead I (left hand, right hand) is consistently yielding unclassified ECG recordings
Try Lead II (left knee, right hand) to improve voltage and recording quality
You can record off your knee even with your pants on if you are prepared to spray liquids on your pants
In March of 2017 AliveCor introduced Kardia Pro, a cloud-based software platform that allows physicians to monitor patients who use the Kardia mobile ECG device.
I have been utilizing the Kardia mobile ECG device since 2013 with many of my atrial fibrillation (AF) patients and have found it be very useful as a personal intermittent long term cardiac monitor. (see here and here)
I signed up for the Kardia Pro service about 3 months ago and all of my patients who purchased Kardia devices prior to March of 2017 have been migrated automatically to Kardia Pro by AliveCor.
Now (post March 2017), patients who acquire a Kardia device must sign up for the Kardia Pro service at $15 per month to connect with a physician.
I think this is money well spent and I’ll demonstrate how the service works with a few examples.
Monitoring Patients With Atrial Fibrillation
I saw a 68 year old man with persistent atrial fibrillation that was first diagnosed at the time of pneumonia in late 2017.
He underwent a cardioversion after recovering from the pneumonia but quickly reverted back to AF. His prior cardiologist offered him the option of repeat cardioversion and long term flecainide therapy for maintenance of normal sinus rhythm (NSR) but he declined.
When I saw him for the first time in the office a month ago I listened to his heart and to my surprise, noted a regular rhythm: an AliveCor recording in the office confirmed he was in NSR. The patient had been unaware of when he was in or out of rhythm
We discussed methods for monitoring his rhythm at this point which include a 24 Holter monitor, a 7 to 14 day Long Term Monitor, a Cardiac Event Monitor and a Mobile Cardiac Outpatient Telemetry device. These devices are helpful and although expensive are often covered by insurance. They require wearing electrodes or a patch continuously and the results are not immediately available.
I also offered him the option of monitoring his AF using a Kardia device with the recordings connected to me by Kardia Pro.
He purchased the device on his own for $99, downloaded the app for his smartphone and began making recordings.
I enrolled him in my Kardia Pro account and he received an email invitation with a code that he entered which connected his account with mine, allowing me to view all of his recordings as they were made.
When I log into my Kardia Pro account I can now view a graphic display of the recordings he has made with color coding of whether they were considered normal or abnormal by Kardia.
The patient overview page also displays BP information if the patient is utilizing certain Omron devices which work with Kardia.
The display shows that after our office visit he maintained NSR for 3 days (green dots) and then intermittently had ECG recordings classified as AF (yellow dots) or unclassified (black).
The more he used the device and got feedback on when he was in or out of rhythm the more he was able to recognize symptoms that were caused by AF.
I can click on any of the dots and six second strips of the full recording are displayed. In the example below I clicked on 2/27 which has both an unclassified recording (which is atrial flutter) and an AF recording
Clicking on the ECG strips brings up the full 30 second recording on a page that also allows me to assign my formal interpretation. In the example below I added atrial flutter as the diagnosis, changing it from Kardia’s unclassified (Kardia’s algorithm calls anything it cannot clearly identify as AF that is over 100 BPM as unclassified.)
The ECG can then be archived or exported for entry into an EHR.
The benefits of this patient being connected
to me are obvious: we now have an instantaneous patient-controlled method for knowing what his cardiac rhythm is doing whether he is having symptoms or not.
This knowledge allows me to make more informed treatment decisions.
The Kardia Pro Dashboard
When I log into kardia pro I see this screen.
It contains buttons for searching for a specific patient or adding a new patient. Adding new patients is a quick and simple process requiring input of patient demographics including email and birthdate.
From the opening screen you can click on your triage tab. I have elected to have all non normal patient recorded ECGS go into the triage tab.
Another patient’s Kardia Pro page shows that he records an ECG nearly every day and most of the time Kardia documents NSR in the 60s. Overall, he has made 773 recordings and 677 of them were NSR, 28 unanalyzed (due to brevity) , 13 unclassified and 55 showing AF.
Monitoring Rate Control In Patients With AF and Reversion Post-Cardioversion
Another patient I saw for the first time recently has had long-standing persistent AF. His previous cardiologist performed an electrical cardioversion a year ago but the patient reverted back to AF in 40 hours. Before seeing me he had purchased a Kardia mobile ECG device and was using it to monitor his heart rate.
After he accepted my email invitation to connect via Kardia Pro I was able to see his rhythm and rate daily. The Kardia Pro chart belowshows his daily heart rate while in atrial fibrillation. We utilized this to guide titration of his rate controlling medications. Such precise remote monitoring of heart rate in AF (which is often difficult to accurately assess by standard heart rate devices) obviates the need for office visits for 12 lead ECGs or periodic Holter monitors.
I performed a second cardioversion on him after which he made daily recordings documenting maintenance of NSR. With this system we can determine exactly when AF returns, information which will be very helpful in determining future treatment options.
Kardia Pro Plus Kardia Mobile ECG Creates Personal Intermittent Long Term Rhythm Monitor
There are many potential applications of the Kardia ECG device beyond AF monitoring (assessing palpitations, PVCs, tachycardia, etc.) but they are all enhanced when the device is combined with a good cardiologist connected to the device by Kardia Pro.
I’ve gotten spoiled by the information I get from my AF patients who are on Kardia Pro now. When they call the office with palpitations or a sense of being out of rhythm I can determine within a minute what their rhythm is wherever I am (excluding tropical beaches and mountain tops) or wherever the patient is (for the most part.)
On the other hand patients who are not on Kardia Pro have to come into the office for 12-lead ECGs. When they call I feel like my diagnostic tools are limited. Such patients usually end up getting one of the standard Long Term Monitoring (LTM) Devices. If I am fortunate, after a few days to weeks , the results of the LTM will be faxed to my office.
I am optimistic based on this early experience with Kardia Pro that ultimately this service in conjunction with the Kardia Mobile ECG device (or similar products) will replace many of the more expensive and inconvenient long term monitoring devices that cardiologists currently use.
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
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.
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.
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!
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.