Apple Watch ECG and recorded Heart Rate data

Inconclusive means it's not AF (according to the watch) but otherwise it could be a problem and to consult a physician. If the rate is sustained over 110 BPM, seek help soonest after 24 hrs have passed with no change or if you feel dizzy, unwell, are short of breath.

While some people on this board will swear by their Apple Watch data, my three year experience with it has been mediocre. A couple of years ago it picked up afib when I did a random EKG. I have elected the weekly report of afib options and it will indicate afib anywhere from 7% to 25% of the time. My Mayo cardiologist thinks it’s confusing PACs (multiple Holter Monitors have had my load at 10-12%) with afib and its algorithm does something funky with the data. Electing the Apple Watch option for identifying an irregular heartbeat in real time has never alerted to anything. I wear it to monitor my heart rate on my runs and get little use out of it otherwise.

I believe that my Apple Watch is reasonably accurate when I take an ECG reading. I have encountered a few occasions when it indicated an "inconclusive" reading, ie: an irregular heart rhythm other than Afib, such as multiple PACs or PVCs. I also have a Kardia device, which will identify PVCs and PACs when they occur. The thing about both devices is that they capture a moment in time, as opposed to a wearable heart monitor such as a Zio patch (prescription required), which keeps a sustained log of heart rhythm activity over a period of days or weeks, thereby providing more meaningful data.

The Apple Watch has two distinct mechanisms for recording heart rate.
One is PPG (photoplethysmography), which uses the light on the back of the watch to measure changes in light absorption with each heartbeat. This allows it to measure beat-to-beat timing intervals, but it does not record the cardiac rhythm. In other words, an extra beat from the top chamber (premature atrial complex, PAC) or from the bottom chamber (premature ventricular complex, PVC) could both alter timing and would not be differentiated by the light on the back of the watch. Additionally, PPG can be subject to artifact—for example, with changes in body position. As a result, a very brief increase in heart rate to 150 or 160 beats per minute, lasting only a few seconds and associated with no symptoms, is generally not concerning and does not warrant additional evaluation.
On the other hand, the ECG function, which requires placing your opposite hand on the crown of the watch, records the electrical signals of the heart. Although the watch’s algorithm is generally accurate, PACs, PVCs, or other sources of variability may cause the algorithm to render a diagnosis of “inconclusive,” or at times indicate atrial fibrillation when atrial fibrillation is not actually present. However, because this is a true recording of the heart’s electrical activity, a physician can review the actual tracing and make a clinical determination.
Apple Watch ECG tracings can therefore be quite useful clinically, although they are not as robust as a Kardia 6-lead ECG, which has more leads and less smoothing/filtering, making it easier for human interpretation (p-waves are easier to see, generally). Watch tracings are also less comprehensive than wearable patches or implantable loop recorders used for long-term monitoring that provide longer data recordings, but may at times also have artifact.
Very brief episodes of high heart rates without symptoms are not concerning. Rhythms that are associated with symptoms should be recorded using an ECG at the time of the symptoms, and those recordings can then be reviewed by a clinician.
At Mayo Clinic, there is currently an ongoing study called the Heart and Voice Study, which allows participants to record voice segments on their phones and, if they have an Apple Watch or an Android-compatible watch, to contribute data from those devices as well, including ECG signals from an apple watch. The watch ECG data are then automatically transmitted to a dashboard in the Mayo Clinic electronic medical record, and made available to clinicians. While this is a research study, the recorded ECGs can be reviewed and used to help address clinical questions.

I have gotten Apple inconclusive with mixed pvcs and pacs. My cardiologist confirmed it. Apple has been a great tool for me to ask questions of the specialists. I have gotten other trends data from the health aP too. I too get h hr notifications but I set to only get notifications if they last ten minutes. I also limit how often I check data-it can drive me bonkers. I am looking at trying another wearable there are a lot of options, considering Hume. Best Wishes

My watch will say inconclusive, sinus rhythm or Atrial fibrillation, those are the only three options. If it says inconclusive I know it is either a bad recording or an unidentified arrhythmia. Make aure your watch is snug, not loose, because that will affect accuracy. When I get inconclusive, I go to my Kardia for actual result

@nevets
You are correct in assessing the usefulness of each of the referenced heart monitoring devices. They were not meant to replace the advice of a cardiologist. That said, their usefulness has been important for some of us to offer a clue as to the direction and intensity of our Afib issues. In prior decades, most of us, including the medical establishment, were "flying blind" without these devices. My Apple watch and the Kardia most assuredly were instrumental in partnering with my Cardiology staff in arriving at treatment for my Afib, which was not only miserable, but life-threatening.

@vickilf5 - Moeys here, thank you for the information you posted it is helpful.

I have a long history of heart issues including NStemi heart attack, stents with lithotripsy, medicated balloon, 4 -89% blocked with full opening accomplished with a very complex PCI. I'm thankful!!! I had my first Medtronic Pacemaker placed in 2010 and in the interim I have had a few more stents placed and a Pacemaker replacement in 2024 due to battery depletion on the original. I was diagnosed with AFib quite a few years ago, never had any symptoms at all, none of any kind. My electrophysiologist said it was paroxysmal. However, they did push for having the Watchman procedure and to start Eliquis or Xarelto to mitigate a blood clot. It was difficult to understand that I would need this 'controversial' medication(s) for something that I had not detectable symptoms. I have been on Aspirin 2-81mg Enteric coated aspirin and Plavix for many years and doing well. I saw the bleeding my husband experienced with both Eliquis and Xarelto when I was his caregiver for 5 years before he passed. I truly do not want to endure that and have not agreed to either medication or the Watchman yet.

I feel very good after the last very complex PCI and the opening of the very blocked areas, it's like a new way of living. I read a lot about the recent studies and even the doctors and researchers do not totally agree on 'one way or the other' as the best. We are all different, no body has been created the same.

I also have an Apple watch and use the EKG occasionally, but I've been told that because of the Pacemaker either the Apple watch or the Kardia do not show accurate readings as the Pacemaker is controlling the pace of my heart. So I am confused about what is being recommended. Are they being suggested to up their surgery 'count', prescribe more medication 'count' or is it really a medical treatment.

I never have heart rate in the 100's unless I am on my treadmill doing my slow walk or at the Y using exercise equipment. Someone on this site mentioned something called Hume, is that a viable option for someone with a Pacemaker, or if one has a Pacemaker are these seemingly devices like the Apple watch or Kardia just not worth it for someone with a Pacemaker. Thank you for your help.

@moey2720 You have a lot of complex issues, and so it’s very important that you have a doctor whom you trust who can work with you in navigating these. The thoughts below are more general comments for your consideration.
First, regarding your question about using an Apple Watch or Kardia device with a pacemaker: they are not incompatible, and you can use both. However, a pacemaker has electrodes inside the heart that record the heart’s electrical activity very accurately. Thus, if you have fast heartbeats, they should be well detected by the pacemaker, although there are exceptions and technical situations where it may not be sufficient. In general, however, a pacemaker would provide the most accurate determination as to whether or not you have atrial fibrillation (a fast heart rhythm in the top chambers of the heart) and how much of it you have.
Importantly, while some people with atrial fibrillation feel their heart racing, other people do not. That’s because the top chambers are racing, but your pulse is driven by the bottom chambers—the ventricles. In some people, not all of the signals from the top chambers make it to the bottom chambers, so part of the heart is racing while the main part that controls your pulse may be normal or slow in its rate.
You asked a lot about whether or not a Watchman device or blood thinners are needed. This, again, is something that is very important to discuss with your doctor. In general, when atrial fibrillation is present, the top chambers are not squeezing effectively. All of us are born with a left atrial appendage, a small cul-de-sac or reservoir in the top left chamber of the heart. Ninety percent of the clots that form in the heart in patients with atrial fibrillation come from that area. If a clot forms (because the blood doesn’t circulate effectively in AF, it may clot) and leaves the heart it can plug an artery; if that artery is in the brain, the part of the brain doesn’t get enough blood and oxygen and those cells die: a stroke. If you are at risk for a stroke, the ways to prevent it in AF are either to use a blood thinner so that clots do not form, or to place a plug in the appendage (the pouch where blood is most likely to stagnate and clot), such as a Watchman device or a different device. This, in the long term, may eliminate the need for blood thinners and prevent the risk of stroke, because clots cannot form in the appendage and then leave the heart to plug arteries in other parts of the body.
The risk of stroke is not determined only by whether or not atrial fibrillation is present, but also by other risk factors. There is a scoring system called the CHA₂DS₂-VASc score, with each letter representing a risk factor: congestive heart failure, hypertension, age over 65, prior stroke or TIA, vascular disease, age over 75, and female sex. Thus, determining whether or not you are at risk is important in guiding these decisions, and the score is one tool widely used clinially. Getting back to my previous point, it is really important that you have a doctor you trust who is well-versed in this area and can guide you through it.
Best of luck as you navigate these complex decisions.

Vicki - Thank you for your reply! Yes, I have wonderful heart specialists at Abbott here in Minneapolis. Dr. Sengupta, and Dr. Brilakis (Interventional Cardiologist extraordinaire) and Dr. Chris Spoke, internal medicine. I have discussed all of the issues ad nauseam with each, but my 'gut' is telling me to stay away from blood thinners OTHER than the aspirin and Plavix. Yes, my history is complex with an exercise induced TIA more than 30 years ago, over 80, BP, on levothyroxine, Chadsvasc of 7 but a couple of Docs have put it at 4 because of the non traditional TIA 32 years ago. I believe I will decide to opt for the Watchman after the first of the year, but no blood thinners. I think that is prudent. Obviously, I don't want to suffer a stroke as a hospital stay is not in my directive. I didn't want to burden you further with extensive med hx but I sure do appreciate the information as I am always learning and my providers are very helpful with that too. Thank you!