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I don’t know about the ECG part, but buying an Apple Watch has definitely made me exercise more
How so?
Apple Watch 'gameifies' fitness. You set a goal of burning a certain amount of calories, "moving" a certain distance, etc. -- and it tracks these things, and gives you little "awards" for when you successfully meet your goals per week or per month, and tries to encourage you in smart ways if you're not making your goals ("Hey if you do a brisk walk in the next few minutes, you'll have met your goal!!"). I find that these reminders work pretty well for me.

As well, if you have peers who have Apple Watch/fitbit, there are tons of apps you can use to "compete" with them.

Paywalled, and not in the .is archive.
You can easily get around Medium's paywall by opening in incognito window
You can also use a script blocker. Medium's site is annoying enough I've disabled all of their JS with uMatrix. Most journalism paywalls are half-assed JS-dependent paper tigers, and I don't know why they befuddle so many "hackers" here.
The doctor says buy it if you think its ‘nifty’ but do bit buy it for health since it will not make you healthier. That’s crazy, it will certainly not make every person healthy still like a personal trainer it cant make you do anything but it can certainly encourage much healthier habits as it does for millions of people like myself with real world tangible results. He dilutes his more valid concern about his belief of saving lives from AFIB may or may not outweigh the inconvenience false postives could cause.
Do we have any evidence that these devices lead to long lasting changes? We know that fitbit doesn't.

Or, better, that they lead to reduction in all cause mortality or reduction in days lost to disability?

So the argument of the article is that widespread screening may cause net harm. The issue is with the imprecision of the test, as well as the followup procedures necessary to be precise, and the probability of mistreatment.
No. We know that widespread screening does cause harm, even if the tests are 100% accurate.
Could you show me the evidence for this so I can be educated.
Some info regarding possible harms of prostate cancer screening: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5485506/

Relevant snippet: ‘The potential gains of screening are opposed by reduced QoL related to diagnostic biopsies, burdensome cancer treatment, including radical prostatectomy (RP), radiotherapy (RT), and androgen deprivation therapy (ADT), and the frequent long-term treatment-related adverse events, including erectile dysfunction (ED), urinary incontinence (UI) and bowel dysfunction (BD) [12–14]. In addition, RP has a small risk of peri-operative death [12, 13].

Finally, since a substantial fraction of PCas shows late onset and slow progression, overdiagnosis and overtreatment are common consequences of screening, especially when it is performed repeatedly or in men with relatively short remaining life expectancy due to age or life-shortening co-morbidity. Overdiagnosis and overtreatment are difficult to assess in empirical studies, because it would require a lifelong follow-up of men randomized to no screening and various screening options in a study without migration bias.“

Those sound like consequences of improper reactions to screening results, not consequences of screening. The solution should be to make better decisions with the results.
As long as we are dealing with humans, “improper reactions” to screening results are a consequence of screening :)
Ok, but we should still separate our improper screening due to inevitable mistakes from improper screening due to not having good procedures in place.
Isn't this more of an argument that we shouldn't necessarily treat everything we observe, rather than that we should observe less?

I get that screening may not be worth the cost, but if the screening is effectively free... then it seems the problem is more in how we respond to the answers.

The ethical argument is that failure to detect a life threatening condition in 100 people is not the same evil as causing a life threatening condition in 1.

What it boils down to is the rate of false positives versus the rate of undetected positives (as opposed to false negatives). If, for example, the Apple Watch in use by 1000 people detects 3 people who with a-fib who previously were not aware of their condition, we might say, "excellent!" But on the other hand if it turns out that one of those people didn't have a-fib, was put on medication and suffered complications, we now have 1 person needlessly suffering who wouldn't have been suffering before and 2 people who are in no better or worse shape than they would otherwise have been. If the regular detection rate of a-fib leads to about 1 person in 1000 being granted an improved quality of life, has the a-fib detection program been useful or harmful?

Then it gets worse: what if the test we use to "diagnose" a condition have a high false positive rate? One example is screening for lung cancer: the screen itself has a 35% false positive rate, but the condition has a 2.1% fatality rate in the population. If you don't screen at all, 21 people in 1000 will die from lung cancer. If you screen, you end up saving about 10% of the people with lung cancer (about 3 out of that group of 21). But the screening means over 350 people end up being told they have lung cancer when they don't, 25 people end up being subject to an invasive procedure to diagnose the condition, and 3 (otherwise healthy but falsely diagnosed) people develop a major complication as a result of the invasive procedure.

Is all that harm done worth saving three lives?

The above is illustrated in this paper about lung cancer screening: https://t.co/YlbZIraekL

That depends on the test. For example, prostate cancer screening isn’t thought to be helpful because most older men have it, but few die of it, but breast cancer screening is thought to be worth it, even with false positives.

Also, if we had a cheap, 100% accurate test for “prostate cancer will cause you serious trouble in your lifetime”, i would guess it would be worth using it.

It really sounds like a software issue to me. If the watch is causing atrial fibrillation to be detected too often, then you can either make the software meet some greater threshold before alerting the user.. or, even better, determine more fully formed diagnostic criteria to be applied.

The fact that medicine hasn't studied whether or not healthy hearts are regularly doing this because sensors were inconvenient previously, doesn't mean we need to get rid of the sensors. It means that both the presentation of the software should have some sort of feedback loop from clinical research that should emerge as a consequence of that data now... existing.

> you can either make the software meet some greater threshold

That will, on the other hand, increase false negatives. I think that will defeat the whole purpose of putting the sensor in the watch.

> medicine hasn't studied whether or not healthy hearts are regularly doing this because sensors were inconvenient previously

Medicine has studied this. It is just that this specific kind of diagnosis is subjective and there are a lot of debate.

The main point, from what I understood, the author is arguing is that the one-lead EEG of the Apple watch is prone to higher false positives, and users should take it with a grain of salt.

The way I read it, applying something with a nonnegligible false positive rate to a much larger population (that is, screening everyone without indications) will lead to many incorrect diagnoses because your error rate is multiplied by a large healthy population. Whereas applying diagnostic tests only to people with suspected a-fib gives you a smaller group with a higher base rate of what you're looking for, so false positives are not as much of a problem.
“Since all medical interventions come with risks, many people will suffer harm from unnecessary tests and procedures.”

I agree with this statement generally, but in this specific case it seems tenuous. If the iWatch’s 1-lead EKG detected a-fib, the next course of action would be a more reliable diagnostic, specifically a proper 12-lead EKG interpreted by a qualified medical professional, perhaps followed by a Holter monitor to record 5 or more leads over a 48+ hour period.

A 12-lead involves attaching ten electrode stickers to a patient which are then wired up to a backpack-sized monitor which passively reads the difference in electrical activity between specific electrodes. It’s a simple non-invasive procedure that’s performed a hundred thousand times a day in the US. In fact, it’s so simple and low-risk that I as a lowly EMT am allowed to perform it. (To drive this point home, the state of California does not allow me to prick a patient’s finger to get the drop of blood required to ascertain blood sugar. I need a paramedic to do that for me.)

It’s absurd for this doctor to suggest an asymptomatic young person could be prescribed anticoagulants for a-fib “diagnosed” by an iWatch. I can understand doctors expressing opposition to “self-diagnostic medicine” but to make these arguments about a 1-lead makes as much sense as arguing that people shouldn’t be able to buy and operate a blood pressure machine without a prescription.

Not so “absurd” - you may be missing some context.

A 12-lead ecg can diagnose whether you have a-fib at the time of the ecg. The question for the doctor is whether you may have “paroxysmal” ie intermittent a-fib. So what if the Apple Watch said ‘a-fib’, but the 12-lead is negative. Most doctors are probably going to end up ordering a holter- monitor, to monitor the patient’s rhythm over 24-72 hours. Some proportion of those patients may have very short runs of a-fib, and would likely have remained blissfully ignorant (and well) without the Apple Watch. Instead, they may well end up anti-coagulated, because if that patient is not anticoagulated and gets a stroke later ( which may or may not be due to a-fib), the doctor is going to get sued. Whereas if the doc starts the patient on anticoagulants, and tells the patient that, “ there’s a risk of bleeding, but...”, that is much less likely to end up in a lawsuit.

FUD
Feel free to counter my statement with actual arguments, I’m assuming (principle of charity here) that you do have some.

Decisions are really easy to make when you have no responsibility - whereas having one of your patients die from brain bleeds on anticoagulation (as well as having patients stroke out when anticoagulation might have prevented it) tends to give you a healthy appreciation for the harms on both sides of a decision that you make about people’s lives

What? That "context" seems absurd considering that the alternative is that the person has 0 warning and 0 indication of either kind of a-fib. Even if the person doesn't have paroxysmal a-fib but the Apple Watch detects an irregularity, I think it would be grossly irresponsible for a doctor to prescribe anticoags without confirming some kind of condition.
Wait, so the argument against having more data is that sometimes that data is misinterpreted or misunderstood? That does not seem like a good argument.
The cost to a false positive in terms of stress alone should not be underestimated.
If you are not going to act on the information, then the extra expense of the exam is wasted.

If you are going to act on the information, then you must weight the benefit of early detection against the damage caused by unnecessary exams and treatment when there are false positives.

False positives are specially problematic when screening a large number of healthy people.

The persistent monitoring afforded by devices such as Apple Watch will directly lead to an increase in the detection rate of any condition that they are capable of detecting. These new detections will be conditions that had been previously undetected.

Whether you class these as false positives (because the existing test suite doesn't detect them) or false negatives (because the existing test suite should have detected them) is perhaps a matter for debate. The practical outcome is more people living healthier lives because their persistent malaise has finally been identified.

At first I was wondering how scheduling someone for a long-term ECG would cause damage, then I remembered that this feature will only become available in the USA soon. Given that the USA is a country where unexpected health care can destroy a person's life through either bankruptcy or the curse of being a woman/person of colour, yes I agree that detecting a previously undetectable condition could cause damage.

There has been a lot of recent research and recommendations for policy change around reducing the frequency of screenings for various things.

Time and data will surely tell if this type of ECG screening is helpful or harmful on a population level. Certainly, some people will get a secondary ECG indicating intervention is required, and the intervention will improve their lives. Others may have a negative result from the intervention, and may never have found their way into this intervention without this screening. For some, this screening indicating a problem but a full screening indicating nothing will drive persistent anxiety.

It is absolutely not the case that more medical intervention is an unqualified good, even ignoring the economic costs.

it's a very reasonable argument if the outcomes of this are overtreatment or serious health scares and increased cost with little payoff as a result.

More data is useless if your data is mostly noise and if as a result error rate in treatment and costs rise. Add to this the strong incentive for doctors, especially in a profit-driven healthcare system to suggest action, this could easily lead to the rise of unnecessary treatment of benign abnormalities in otherwise healthy people.

This is also not speculation. Ever since the rise of diagnostics in medicine overtreatment has become more and more common. This study[1] estimates that almost a fifth of all procedures in the US are not necessary.

[1]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5587107/

Interesting standpoint, one which I disagree with.

You are making a causal connection of rise in diagnostic tools => overtreatment. What is your evidence for that, apart from overtreatment increasing? I think sea levels have risen since then too, are they also an effect of too much diagnostics?

Clearly, if the data was just noise, people would eventually stop caring. But you'd have to be pretty cynical to think one of the major tech companies of the world releases a diagnostic device that has an S:N ratio that high.

A more likely explanation for the overtreatment is simply that people are getting richer, and society is providing more care -- to a fault. I know this first hand, I have had invasive surgery done that I would've been better without -- because the doctor thought it maybe might be a good thing for the future. Spoiler: it worsened the problem.

I think if it were the case that we all suffer from a bit of a-fib every now and then, and that these diagnostic tools will give false positives for this reason, then that would be news to the medical community and thus progressing our understanding. People would be told, "your watch is telling you this but we know better now." Apple might update their detection algorithm. It's such a small price to pay for the obvious advantage of preventing loss of life.

Who is arguing against more data? Even the author of the article is essentially saying “buy it if you like it, just don’t buy it as a medical device”

On the other hand, maybe more data could be harmful? You might be interested to read a classic article (Bergman, 1967, [“The morbidity of cardiac nondisease in children”](http://dabamirror.sci-hub.tw/4363/be7b5e26e14c6389108fbdc70f...)

It discusses the harm to children of their parents believing their child has a “heart problem” when they have a completely benign murmur - which raises the issue of whether you should tell a parent there is a benign heart murmur when that information might actually be harmful - and whether that risk of harm is sufficient to override the parent’s right to know.

Another example will soon be genetic testing for risk of Alzheimer’s disease - if, at present we have no way of reducing the risk, is it fair to give people that information, when we know based on many studies that such knowledge lowers patient’s quality of life?

I think free adults should have the right to do all sorts of things that others think might be harmful - but it also seems reasonable (as this article does) to make people aware of the risks of “more data”, as well as the assumed benefits

I think it's a stretch to call this murmuring anecdote a case of more data => negative outcome. It's more like telling an individual about their specific instance and then having them extrapolate from uncertain statistics and overcorrecting. Acting on bad intel, as it were, where n=1.

If you want to argue against gathering information in this way, then perhaps phrenology serves as an interesting example. We know now that most likely, it was a croc. The use of phrenology was to draw a boundary around a certain ethnicity so that it could be upheld above all other ethnicities, and so it is hard to say that the data collection itself was the problem. Sweden is having a similar but opposite problem right now -- assault and sexual assault perps are predominantly Arabic immigrants, for one reason or another -- maybe it's in part Middle Eastern culture, almost assuredly it's a lot about socioeconomic factors, but nonetheless, it is true.

The powers that be have decided that the news should not mention ethnicity or citizenship for fear of racist backlash, they have decided that the annual crime statistics reports should not mention ethnicity or citizenship, again citing fear of racist backlash. I now invite you to consider, what will the population think then, if there are no facts to refer to, nothing to dissuade the racist's viewpoint that "Muslims are bad people?" Facts are sometimes inconvenient or inflammatory, but that doesn't make them less true.

For your case, I think the problem is not one of information gathering. Doctors should still be examining the kids, I think you agree -- the problem is giving the wrong impression to the parents, or not knowing that it is in fact the wrong impression.

This watch is not a prescription, nor a doctor ordered monitor. Even more, as mentioned its detection quality/history is not as reliable as to what currently a doctor would trust (as in case of 12-probe ecg).

Heart risk is serious and by itslef warrants a GP visit or at least a question. Yet a recreational health monitoring looks similar to someone's reading a GP's handbook for fun - suddenly lots of descriptions seem to apply due to uninformed perceptions.

Either way, if one has reasons to believe being at heart risk, watch is not the first thing to buy to be pro-active/preventive.To have the watch does not mean to take care of the risk. Just like having a fitbit does not mean one is actively fit.

Exactly. And what's funny is that people seem to think that physicians make accurate judgements all the time and don't make mistakes. And that there are not a host of gray areas which are taken into consideration.

Maybe a similar example is with a dog bite. If you say 'no it was my dog and they are not rabid' then doctor says 'ok no rabies shot needed'. If you say 'it's a wild dog (or friends dog)' and you don't know if it's rabid doctor thinks 'rabies shot needed'. Even if the actual chance of rabies (in your friends dog) is quite small (if the friend doesn't know if the dog has shots I mean).

More info is not only not always helpful but comes with risks as well. If not we would monitor things more frequently than we do and the simple scale would lower the cost.

Would you say that, on the whole, physicians will make judgements that are approximately as accurate given new data about paroxysmal a-fib as they did before having this new data?

Are they already condemning people to unnecessary treatment on the off-chance that treatment is helpful?

Is there scope here for the AMA to refine procedures to suggest holding off on medication when a condition is only discovered by a persistent monitoring system such as Apple Watch?

Even if the over-medication issue increases, are the live saved via early detection of equal value to the lives damaged by unnecessary medication? If there are more lives saved than damaged, is there a net benefit to society, or are we only interested in the lives lost through action and not at all concerned about the lives lost through inaction?

Something isn’t right when you’re considering lawsuit potential when making patient care decisions.

I stand by my argument that a GP prescribing an anticoagulant based solely on an iWatch having detected a-fib is grossly negligent (just as—in keeping with my earlier comparison—he would be if he prescribed an anti-hypertensive to a patient who stated they had a BP of 180/120 at home one time).

I’m not entirely sure why you docsplained that 12-leads cannot bend spacetime and that a Holter monitor would be likely be ordered to detect intermittent arrhythmias over a longer period of time, but thanks. Can I claim CE hours for this?

The argument against more monitoring is one of false positives. Suppose the Apple Watch has a 5% false positive rate, and detects problems with 1% of 100 million users.* That's 50k extra patients going to their doctors, thinking there might be something wrong with them. The next test may have a 1% false positive rate. That would put 500 extra patients on anti-coagulants.

That may not materially change the public health calculation, or it may. But that's the calculus -- not that a GP would blindly prescribe, just that increasing the top of the funnel is not necessarily a good thing. (Plus, extra cost.)

Positives and negative impact of additional testing must be measured for optimal decisions.

* numbers to make the math easy

As opposed to the “but I might get sued” argument, I find this argument totally reasonable. Thank you for stating it so clearly.

I’m cautiously optimistic but recognize that we need more data because evidence-based medicine is all about testing hypotheses. The hypothesis here is that continuous 1-lead monitoring will provide a net benefit to the population employing it. Maybe it will and maybe it won’t; Either way I think it’s pretty cool that we’re about to amass a ton of relevant data from which we’ll be able to derive an answer.

Even if "tests" (omg no!) are ordered, they're not going to jump directly to invasive procedures like biopsies or catherization (have had both!$. They're going to do exactly what you've described as a "lowly emt" - thank you for posting this.

Screw this "doctor" and their FUD.

”the next course of action would be a more reliable diagnostic, specifically a proper 12-lead EKG interpreted by a qualified medical professional, perhaps followed by…”

I think you’re missing the argument made (fairly poorly, IMO) in this article: that preventive medicine often isn’t worth the money for society.

For relatively rare diseases, false positives typically outnumber true positives by a wide margin. If that’s the case for this Apple Watch, that means many users will needlessly be stressed thinking “I’ve a heart problem”, something that will cause some loss of QALY’s (https://en.wikipedia.org/wiki/Quality-adjusted_life_year) and will trigger tests that will take resources that may better be spent elsewhere.

That’s for society, though. Richer I ndividuals may not care about the extra costs, and people doing lots of checkups may be less stressed about false positives.

In rural New Mexico, EMTs can do finger sticks and King airways and epi injections and certain other interventions that normally require a medic because our transport times are long. But yeah, we also do ECGs all the time.

What worries me is that a 1-lead ECG is not worth much. If a 12-lead is only 90% accurate, a 1-lead is bound to be much worse.

I don't know how it works in the US, but in the Australian public system you cannot organise a medical intervention without the right results from the proper tests. The Apple Watch in this scenario becomes a symptom for the doctor to assess in order to plan for diagnostic tests, not a diagnostic test in and of itself.
This article needs more analysis. How many people who didn't know about af will be detected by the device, compared to the 100k estimated false positives. And do these pan out the same way for other heart ailments.
I'm not a heart doctor. Here's why I am not wary of the Apple Watch:

1.

At a societal level, perhaps false positives during screening put undue load on the medical system. But as an individual, it makes sense for me to screen for anything that does not take too high of an effort. If there is a false positive, it will be snuffed out in the next test.

2.

Here is a little thought experiment. Lets say the false positive rate is 1%, and you screen 100 people. Then, your total number of tests including repeated tests on false positive subjects will be ~101 on average (the chance of 2 or more false positives is low enough to ignore).

As long as the screening itself is not too much of an effort, then in fact false positives don't add that much load to the system.

So, we should be seeking additional methods for widespread screening rather than worrying about false positive rates.

---

I also find the doctors assumption of 10% false positive rates to be a little self serving in his argument. 1 in 10 people with an apple watch are going to be have atrial fibrillation detection? Doubt it.

That's a lot of words to say that your hunch of a 1% false positive rate is more likely than the heart doctor's hunch of 10%.
That would make some sense if we were talking about tests for long-term state, but from what I understand, the test in question detects a potentially rare and irregular event happening. Which means, you can test yourself 100 times, get one indication of a problem, and still not have enough information to be confident that it was a false positive.
To gain some free publicity by stating the obvious which was already accounted for?
What’s the source for 10% specificity? I couldn’t find any article that said this was the case. In fact the only article that mentions any numbers is written by Quartz and says this: “Cardiologists were able to read 90% of the total readings, although about 10% of them were unreadable.” That’s not false positive.
He did not source it directly, but looking at some ROC curves from AF detection publications the numbers seem completely reasonable.
> I worry that the Apple Watch will discover lots of short-duration AF or AF occurring in younger people with fewer risk factors. Given their lower risk of stroke, it’s unlikely that anticoagulant drugs will deliver similar benefits. But anticoagulants do increase the risk of bleeding.

This is completely grounded in science. And we should be weary of going to the doctor too often:

>Medical Errors Are Third Leading Cause of Death in the U.S.

1. https://www.usnews.com/news/articles/2016-05-03/medical-erro...

The vast majority of these fatal medical errors happen in the hospital, and healthy people don't often end up hospitalized. Much of the time, the alternative to hospitalization is going to be fatal anyway.
So I started having premature ventricular contractions a couple of years ago, and had a lot of anxiety around it — I made multiple emergency room visits and trips to the cardiologists because I was convinced that when they were giving me ecgs, they weren’t getting it when I was having a severe problem and were missing a-fib(which runs in my family)

They eventually told me to get a Kardia so I could check it whenever I wanted to.

After a few weeks of checking every time I thought something was going on and periodically sending the worst examples to their analysts, I realized it was only ever pvcs, and it dramatically lowered my stress levels and made the episodes much less severe and shorter lasting. It also helped me figure out my triggers (caffeine) and helped me realize that going on a brisk walk for 15 minutes pretty much always stops them.

I wouldn’t say the Kardia saved my life or made me healthier, but it absolutely helped me get a handle emotionally on what was going on with my heart and improved my quality of life. I don’t carry it around any more, but I definitely think it’s worth getting (or the new watch) if you have palpitations and want to get a better idea of what’s going on.

The issue is not whether it would be of benefit to someone like you. The issue is if having that feature as well as the downside risk to people who are in the general public and don't have a particular risk factor or need. Also it's not an option it's built in the core product. As such it will alarm people that have no reason to be using it in the first place even if it ends up alerting and saving some people in the process.

Is it worth it to give 1000 people anxiety, tests, medication in order to provide benefit to 10 people or even 100? (those numbers are made up to illustrate and are fictitious).

I understand his argument but better have a false positive than a false negative in my opinion.
This is manifestly not the case, and there are a large number of studies showing why this is true (many linked elsewhere in this thread). Most people do not have a good understanding of the risks associated with ongoing medical testing/medical visits.

A hopefully not-too-inaccurate analogy might be if you heard a strange sound while driving your car, and took it into your mechanic, whose shop gets paid more the more tests they do and the more labor they put into fixing your potential non-problem, and they're potentially liable if anything later goes wrong that could be traced to that sound. Think about where the systemic incentives lie.

The numbers mentioned (90% specificity) are for 100% sensitivity (not mentioned in post). These numbers are for patients taking ECG under controlled conditions. Continuous monitoring for AF under arbitrary conditions seems indeed problematic to me.
I must agree with the potential harm of increased false positives but I am not sure if this is the real issue here. In a short period of time, it is impossible to accurately analyze heart trends to find AFib. I mean, people might feel that everything is okay when it's not (false negatives ARE problematic), which can be only determined in full 24h+ / 12-lead ECG scan. However, 20-30s ECG monitoring is still adequate to gather information about some of the disabilities of the user's heart (for example, if any ventricle is damaged).

When we were bootstrapping with a similar idea as Apple Watch at Aidlab, all cardiologist were looking at us like we were crazy. Well, seems we were talking with wrong doctors, and we should go straight to Dr. Ivor Benjamin.

Utter hogwash. The author's mistake, often made by physicians when presented with technology that gives consumers more information, is that consumer knowledge and attitudes remain static.

In fact, while this may at first lead to a bunch of hypochondriac-like behaviors, people's fascination with themselves will quickly teach them to not be alarmed.

I agree. I was immediately suspicious when the author identified himself as a "heart doctor". The correct term is cardiologist, as everyone knows. He should be communicating directly with the FDA, not blogging about his concerns to raise alarms.
I suppose this doctor will prescribe you to not use all new medical tools available in case they might find something. I don't understand the logic. Having mass adoption tools to check your health is the future. This will never be 100% accurate, but like medicine and doctors will never be.
Yes, doctors and health organizations routinely advise patients not to get more tests than they need. A PSA test is cheap and easy to administer but the consensus is that risk of false positives (among other reasons) outweighs the benefits of finding prostate cancer among young men at low risk.
I’m still not clear on this, perhaps someone can enlighten me: does the watch attempt to do an ECG whenever it can? Or is it something you have to explicitly trigger?

I feel like it must be the first one otherwise people wouldn’t be arguing against it.

The watch monitors heart rate all the time. If it detects some symptoms of a-fib (i.e.: irregular heartbeat) it will prompt the user to use the ECG feature.
Ah, that’s the trick. It prompts for the ECG if it thinks something is wrong based on the regularity of the heartbeat sensor.

Thanks!

Not a fan of the dumb it down title of heart doctor, cardiologist I feel is fairly widely known, and dumbing it down makes me think that they are dumbing or glossing over other points
We know what a cardiologist is, we're not stupid.
In my experience, doctors have widely-varying, fact-free opinions that are often wrong on wearables' personal quant and consumer medical devices' precision & accuracy. Heck, some are even wrong on home-medical equipment. The reasons are medical school drills into them two things 1) only doctors and specialists can be "right" 2) everything else is wrong. This creates an opinion based on narcissism and elitism, rather than data.

Take a FitBit Charge HR 2. The one I have is consistently within 2-5% of hospital & doctor office pulse readings. That doesn't mean it's perfect in all circumstances, but that it's observations haven't been discredited with evidence and there's little/no counterexamples to show that a device I wear is somehow "inaccurate."

Another doctor claimed home blood pressure cuffs, products strictly-regulated by the FDA, are "widely inaccurate." This also seems binary-thinking FUD and wrong, because, anecdotally, I checked repeatedly and have an accurate consumer blood-pressure meter.

This is what happens when a profession encourages people to invest their egos in a preordained outcome.

As consumers we should be demanding to know the sensitivity and specificity of such health products. Doesn't seem responsible of Apple to market such products without that information.