Apple Watch detecting coronary ischaemia during chest pain episodes | Hacker News Reader

Apple Watch detecting coronary ischaemia during chest pain episodes

academic.oup.com

132 points1cvmask56 comments

Impressive utility of the single-lead ECG recording, but I have to say that if I'm in charge, that patient's headed for bypass surgery, not stenting.

I’ll take you up on the bypass statement. :) This is an 80 yo woman, that alone would probably make me not want to put her under for bypass. Also, she had a history of paroxysmal afib and prior pulmonary embolism (they don’t state if it wad provoked or not) but is not on anticoagulation. By CHADS2-Vasc criteria she should have been on AC alone, but isn’t. She’s clearly intelligent and has no issues with access to care (engineer, has an Apple Watch) which further makes me think that her underlying health warrants a more conservative approach.

I agree. Redoing plumbing of an 80 year old house, makes sense only under certain conditions eg- part of a living history museum.

Plus, I don’t want to risk giving the house a stroke or cognitive injury from the risks of the operation and general anesthesia when a comparable or better outcome could be done with PCI. It’s all about risks and benefits for her.

In three vessel disease, PCI is decidedly worse than CABG [1], but the latest evidence is, AFAIK, equivocal for CABG over PCI in one and two vessel disease [2].

I've personally often thought that this is due to the degree of collatoralisation that goes on in the ischaemic myocardium, even when we are convinced that the reduced FFR is all the story: stenosis does not happen overnight and metabolic adaption to, e.g., decreased O2 starts to begin. In three vessel disease you've burnt your reserves and are desperate for O2. In two vessel disease you're (mal)adapted.

Incidentally, this is why my scientific research is focused on using a slightly crazy CMR technique to directly image glycolysis and beta-oxidation in the ischaemic myocardium. We can make PCI kill fewer people if the interventionalists can be told "This region is ischaemic and has shifted towards anaerobic glycolysis due to this branch of (LCx/whatever) artery. Go revascularise".

[1] https://academic.oup.com/eurheartj/article/35/40/2821/229322... [2] https://openheart.bmj.com/content/3/2/e000489?utm_term=usage...

Hyperpolarized 13C MR?

Are you in the field -- and if so, where do you work? UCSF? (I'm in Oxford :-)

Yep :-)

Eh, I think the data is controversial and case-dependent in two-vessel disease. If this were three vessel disease, the data is far more in favor of CABG. The fluoroscopy doesn't look convincing to me of major stenosis, so a PCI/stent could certainly be placed for symptomatic relief without a CABG.

Additionally, the patient definitely did not need emergency CABG. My understanding is that CABG could be completed after stenting, and may very well have happened for this patient without our knowledge.

I'm not sure the HN community participates in the CABG PCI wars, but maybe your comment will lead to a fiery debate.

Never underestimate the ability for HN to participate in an extremely niche flame war.

Please don't make comments like this. We’re also well-equipped to participate in flame wars about the popular culture.

Is this specific to apple watch ? Are the other fitness trackers not suited for this ?

I think the “30 second finger ECG sampling” is unique to the Apple Watch. Most modern continuous trackers use optical heart rate (PPG) alone. Garmin includes a red light PPG that is used as a Pulse Oximeter during sleep to measure SpO2 and they also continuously monitor Heart Rate Variability (HRV) that they report as stress. Garmin also uses machine learning models to predict sleep stages with PPG data without an EEG.

All of these consumer grade sensors are poor compared to the medical PPG, ECG, and EEG equivalents but they have the advantage of being ubiquitous and continuous. They offer the ability to collect a baseline for our health data that is supplemented with short samples during exceptional events.

> I think the “30 second finger ECG sampling” is unique to the Apple Watch.

Check out AliveCor. They had an Apple watch band that provided similar functionality before Apple offered it directly.

Apple Watch is the only mainstream fitness tracker watch that does ECGs to my knowledge (but I’ve honestly not looked extensively), but AliveCor had a product on the market before Apple offering a similar function on Apple Watch (via a watch band w/ sensor), so Apple’s marketing claims of being first are dubious at best. I prefer the Apple Watch version over AliveCor’s by far, but it’s certainly not the only option, let alone the first.

My main beef with AliveCor is the fact that the sensor can pop out of the watch band and when it does and you don’t notice, you’re out $200 (as in my case). It also isn’t as good a user experience, but that’s not a blocking factor to me in this case, just the triviality of losing an expensive sensor which is barely held in by a piece of flexible material.

Withings move ECG is another popular fitness tracker with ECG functionality sold €130.

https://www.withings.com/no/en/move-ecg

> Withings move ECG is another popular fitness tracker with ECG functionality

Hadn’t heard about that one, thanks for sharing. Might work for a family member who won’t wear anything but an analog watch.

Apparently the newest Galaxy Gear watch has the ECG functionality but its not enabled. Last i've heard the waiting to be greenlighted by the FDA to enable it.

Would be great for those of us with an Android phone to have similar options to choose from

I think the Apple watch is (nearly) alone in being FDA-approved as a medical device, and I wouldn't trust anything that isn't. If I didn't need an iPhone to power it I'd buy one in a heartbeat just for health reasons.

"FDA-cleared" not approved. There is a huge difference: https://www.cnet.com/news/fda-approved-vs-fda-cleared-whats-...

I have both but cannot wear the watch because it gives me a really bad rash. It’s apparently not uncommon.

Your sweat could be getting a bit of a current going through it, are there charging contacts near the part of the watch that gives you the rash? Salty water (sweat) and electricity could well be making acid that's causing the rash. Sorry that this isn't really a solution but I find if I don't wear my fitness watch when exercising I don't get rashes.

No, the Apple Watch uses wireless charging so there aren't any exposed contacts that I can see.

There are accessory contacts inside the strap latch. It's possible, though unlikely, that sweat is getting in there.

I had a fitbit back in 2014 and the irritation turned me off of all fitness trackers

In 2019 I got an Apple Watch with stainless steel band and have not had any issues

I had irritation during the first few weeks of wearing my fitbit charge hr but being a bit more diligent about washing it made everything go away.

On which part? Under the watch or the strap? I had a problem with the strap (I sweat a lot) so I got a Nike fabric strap - it breathes a lot, so no effect on my skin.

It should also be noted that there are two types of metal finish on the watch: the aluminium and the stainless steel.

Which version did you try? That is to say, what metal and which band?

What is wrong with an iPhone?

No multi-user accounts possible (work/private separation) or something like Samsung Knox. This is stopping me from switching.

My company recently adopted SecureMail, SecureHub and the other Citrix mobile stuff, it seems to sandbox itself from the rest of the system pretty well. It controls which apps you can cut-n-paste between or share links to for example. I think it's uses MDM under the hood to manage data sharing and permissions.

They actually did just introduce support in iOS 13 for a type of MDM which does works roughly like the Google work profile thing.

There is nothing like f-droid possible on the iPhone.

nothing's wrong with them, it's just that I have an Android phone and don't want to get a new phone just for this.

Very expensive telephone.

While true for most people outside of highly skilled western income levels, if you can't afford an iPhone how can you afford the iWatch to go with it?

You just pay with your data when you get something like xiaomi or basically any other phone. On top of that you get a very good phone and about 5-6 years of software updates. I don’t call €500 (SE) very expensive, though it is a lot of money all at once.

Can get the SE, which is pretty midrange unless you’re comparing it to feature phones.

where i am the SE is 500€. Is a LOT more than the 180€ that i payed my xiaomi. I wouldn't really call it midrange... but i guess it depends where you live?

Considering another 460€ for the watch it become very expensive.

Also not long ago 500€ (here) was considered a notch under top of the line.

edit: as a reference, feature phone extremely rarely surpass the 100€ on amazon and are generically around 50-60€.

edit: fix grammar

Agreed, $500 might be entry level phone in US income money but in Europe(an most of the world) that's a lot of money.

Its not only about can-I-affort-it. Here in Switzerland, most of my IT colleagues have android phones 1-5 years old that were never top of the line and they are fine with them, including me. With salaries that could comfortably afford them latest top apple phones every generation if they wanted.

But why would they do that? Phones are not secure by default, anybody thinking otherwise is naive and uneducated, Apple is not an exception. What else does an Apple phone offer to IT guy that rest doesn't? The answer for most of us, nothing. We just run an app XYZ. And those phones are just fine for that.

SE being no exception to this, its still way pricier than Android counterparts.

Like most of us, for most use cases we don't buy overpriced status things with decent quality, rather stuff that has good price/quality ratio, emphasis more on quality. Same with cars, kitchen, other electronics or generally home equipment, sport equipment and so on.

> I'd buy one in a heartbeat

I see what you did there.

Treat the Apple Watch as a single lead and you can piecewise together a full ECG. Each of the single-lead ECG recording be off by 30 seconds but is good enough for most purposes.

The apple watch ECG corresponds to lead I. Lead II and III is right and left arm respectively to left foot, so they will be possible with a bit of flexibility. The 6 precordial leads are not possible, since they are measuring the voltage between an electrode on the chest and the mean of the 3 extremity electrodes.

The poor man’s single lead ECG is complemented by continuous PPG heart rate data. Being able to combine the data of multiple sensors that are synchronized with a single clock provides new opportunities for monitoring and analysis. HRV data is also useful and I’m surprised that it hasn’t been used to estimate the respiration rate.

Quite unlikely they did not try. Reflectance pulse oximetry is unfortunately affected a lot by ambient light and so, even for the Apple Watch, that might have caused unreliable measures.

Using the ECG for RR estimation though should be more than feasible...

I have very little understanding of how an ECG works. Can you ELI5 why a single-lead ECG recording can be off by 30 seconds, and what that means?

He means that you would have to do many single-lead recordings separately, rather than a multi-lead recording once. The standard length of the Apple Watch ECG recording is 30 seconds.

pretty cool -

anecdotally I've had a funny call or two involving Apple watches (as an EMT).

My favorite was during a local celebration of the "Holi" festival (aka Indian festival of colors). It was setup in a waterfront park and we had an EMS station and got a series of calls through the day. One case a young woman came up to our station to say a guy was maybe having a heart attack... We followed her to a tall, lanky college age kid seated on a stone bench freaking out - labored rapid breathing, etc

Talked to him a bit to get some history and he kept showing us his watch - his skin and watch (and just about everything else) was caked in the fine dust which folks were throwing into the air and at each other. It was reading some absurdly high (or low I don't remember) pulse rate. But the guy was talking in full sentences - had good perfusion and seemed to know who he was and where he was, etc.

I don't remember if we gave him oxygen - we took his vitals manually and eventually convinced him that the watch was not reading correctly. He calmed down and refused further attention and was back hurling packets of colored dust at his buddies in a few minutes...

Its awesome people are using these devices (pulse ox devices are excellent for detectign silent hypoxia in Covid cases even before a person has obvious signs - see recent NYTimes opinion piece)

Even if they are nto accurate (and they generally arent) they give the person a baseline.

"Usually my pulse is x and now it is y" is useful information for an EMT anyway (we don't diagnose as we are not doctors - we look for obvious life threats and rate of change for various external signs).

Just don't freak out if your device is malfuntioning. Have a second or third way to verify a vital sign...

> pulse ox devices are excellent for detectign silent hypoxia in Covid cases even before a person has obvious signs - see recent NYTimes opinion piece

I'm having trouble finding the opinion piece... If someone bookmarked it please post it here :)

https://www.nytimes.com/2020/04/20/opinion/sunday/coronaviru...

If I am reading the abstract correctly, it seems a medical procedure was carried out here based on evidence solely from an apple watch. Other medical tests either came out fine or weren't carried out.

Doesn't that break a million rules? What if that trace was just the result of Apple testing out a new data postprocessing algorithm?

Naah, they merely looked at Apple Watch graphs and skipped more noninvasive diagnostics directly to invasive diagnostic procedure - aka catheterization aka angiography. Angiography is the real test that can find the blockage but is invasive, so not done unless there is solid suspicion.

Summary of the paper: Apple Watch was right. They found the blockage and fixed it.

I don’t think Apple can get FCC approval if they just test new algorithms on end user devices.

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