On Wednesday September 12th 2018, Apple COO Jeff Williams got on stage at the Steve Jobs
theatre and announced that the Apple Watch Series 4 would come with a built in ECG - or
electrocardiogram - giving the user the ability to see the real time electrical activity happening
in their heart.
Sort of.
It’s technically a rhythm strip, but whatever.
This has never been built into directly into a wearable before and is what scientists would
call a big frickin deal.
While the accuracy of the reading is for sure going to be tested in the future, it begs
the question: what’s the difference between this $400 accessory and a full fledged 12
lead ECG?
Some quick background:
Heart disease is the #1 killer in the western world, so there’s a need to find arrhythmias,
or abnormal heart rhythms.
To diagnosis arrhythmias, a doctor will choose to use a full blown electrocardiogram, usually
after a life threatening event or when they suspect something’s wrong.
In the hospital, the medical team will attach adhesive electrodes in strategic places around your
chest and abdomen to get a good recording of pulses.
And different pairings of electrodes produce what’s called a lead, to make the industry
standard 12 lead ECG that looks like this.
Great for use in the hospital, but what about when patients are living their regular lives?
Portable ECG units have been available for a while, but they’d still only be prescribed
for a short period of time and only if there’s a suspicion of finding something.
So with any portable unit, you lose the detail from a full 12 lead.
But what you lose in detail you gain in the continuity.
For wearable health tech like the Apple Watch or the FitBit, the big advantage is the continuous monitoring
for people who might not know they have a heart condition.
But while those little green light sensors on previous Apple watches can pick up the
number of beats, they don’t tell you anything about the electrical activity that caused
it.
So to get that info without chest electrodes, developers got the user’s opposite hand
involved so they could complete a circuit.
The first company to do this successfully for a consumer product was a brand called
AliveCor, which made a watch band for the Apple Watch that had an electrode built into
the band.
The user wears the watch on one hand and closes the circuit with the opposite hand.
The Series 4 model does this but with the digital crown instead of a separate band.
But watching the Jeff Williams presentation, and reading some of the articles that came out afterwards,
you notice that the common arrhythmia is Atrial Fibrillation, or A-fib.
That’s because they have the validation of really smart people who have been testing this in the background for the
last few years.
A study published in JAMA Cardiology in 2018 took data from almost 10,000 participants
with heart rate trackers like the old Apple Watch - devices only give heart rate and time,
which give us graphs that look like this.
While these patterns don’t give us a full ECG waveform, they can still give us hints.
Atrial fibrillation looks like this on an ECG, lots of little waveforms instead of the
nice discrete waveforms of normal sinus rhythm.
The study used a deep neural network to learn when it could say “this pattern on the watch
data usually goes with A-fib on an ECG”.
Then they took that data and applied it to 51 patients undergoing cardioversion, a procedure
that helps restore a normal electrical rhythm to the heart.
The study concluded that with this technology, they could find A-fib with a 97% accuracy.
The hope is that the watch will pick up on something, alert the user to go to the doctor
where they get a real deal diagnosis.
And with the blessing of the American Food and Drug Administration, as well as the president
of the American Heart Association giving his personal testimony for the product - there’s
a lot of trust behind these results.
And Apple is still studying this alongside Stanford Medicine.
That study is set to finish in January 2019.
Going forward, it’ll still be a while before more complex arrhythmias will be detectable,
and a $400 watch isn’t gonna touch what hospital grade equipment can do.
But the fact that we now have a tool for screening one of the most common arrhythmias that people have
in a product that people are actually want to buy, is a huge deal.
Thanks for watching.
This is a bit different than my typical anatomy and physiology videos, but the new shiny tech
was too much to resist.
So make sure to check out some of my other videos and subscribe if you’re interested.
Either way, have a great day.
Have fun, be good.
See you next time.