clearances to offer algorithmic analysis of readings to determine
certain heart rhythm problems. This is one of the first examples
of AI replacing the functions performed by living and breathing
physicians. The current version takes about 5 seconds to process
the information using this AI algorithm, and then makes a
determination of sinus rhythm, afib, or unclassified.
Before this technology was available, patients called me in
the middle of the night saying they were having palpitations
and wondered if their afib had re-emerged. The only advice I
could give was to go to the ED and get a tracing (and a nice big
bill, to boot). But with this device, they can make a recording
in 30 seconds, take a screen shot of the image, and text me the
picture of their rhythm. On many occasions, I helped a patient
avoid an inconvenient, anxiety-provoking and expensive trip
to the ED. With the emergence of the AI algorithm for on-thespot
interpretations, those middle-of-the-night phone calls are
less frequent. Alivcor can forward and share patients’ tracings
with their physician in a HIPAA-compliant portal platform
called Kardia Pro. Some cardiologists who have enrolled in the
service say it is a less-expensive alternative to long-term rhythm
monitors.
AND TWO BECOME ONE
So now you have two somewhat helpful cardiac biometric
technologies: a smartwatch-enabled optical HR monitor whose
accuracy is limited from rest to low levels of activity, and an
electrode-based smartcard called the Kardia Mobile for singlelead
ECG recordings. Both of these communicate with your
smartphone via Bluetooth, but if you could marry the two sensor
technologies into one wrist-based wearable, you’d have a game
changer!
And that’s exactly what Apple has done. Initially, Apple
paired the two via the Kardia Band (KB) from Alivcor. (See
photo 3.)
The KB is a wrist-band ECG reader for the Apple Watch,
cleared by the FDA in November 2017 as a medical device. In
the KB, the electrodes now are embedded in a special Apple
watch band instead of in a case or a card. Being able to
conveniently carry around the sensors and record the tracings on
the wrist has made this cardiac biometric device exponentially
more usable and applicable. But wait — there’s more! With the
22 Dallas Medical Journal November 2018
Apple Watch Series 4, the Kardia technology is embedded in the
watch itself. (See photo 4.)
Photo 4. The
underside of
the new Apple
Watch Series 4
shows a simplified
photodiode and an
ECG electrode.
COMPARING SMARTWATCH DATA
TO STANDARD ECG RESULTS
But is it accurate? In March 2018 in the Journal of the American
College of Cardiology, a study was published comparing the
accuracy of the smartwatch/phone compared to the standard
electrocardiogram. At the Cleveland Clinic, 100 patients were
studied who presented to an EP clinic for elective cardioversion
from afib to sinus rhythm (NSR). In this study they used the
smartwatch KB. Smartwatch-KB ECG strips were recorded
and compared with the 12-lead ECG before and after
cardioversion — in other words, in afib and NSR. The Kardia
diagnostic AI algorithm correctly interpreted afib versus
NSR with 93% sensitivity, 84% specificity. With a physician
interpreting the KB recordings, sensitivity increased to 99%.
Another study using the smartwatch KB ECG tracings and
the Kardia interpretative algorithm, also published in March
2018, demonstrated that Alivcor’s ECG device can perform
noninvasive detection of hyperkalemia, via analysis of the
T waves from the rhythm strips. The sensitivity is 90% to
94%. This is important in conditions in which high potassium
levels are frequent, such as in heart failure, chronic kidney
disease and diabetes, and with various medications. These high
potassium levels could be life-threatening, providing another
example where a wearable recorded ECG tracing coupled
with AI technology could be life-saving. In September 2018,
Alivcor received FDA approval for this high potassium detection
function using the KB.
The Kardia technology records only when you purposefully
hold your fingers on the sensors. So, except when you’re having
symptoms, how do you know when to get a recording? Many
episodes of afib are asymptomatic. This is another breakthrough
offered by the Apple Watch Series 4. Transparency alert: The
Series 4 smartwatch was not available at the time of this writing,
so I have not tried it. The Series 4 algorithm created specifically
for afib monitoring will be out later this year, so I cannot report
that its advertising claims are accurate. But I can relate it is
reported that, using the new Series 4 algorithm, the Apple Watch
Photo 3. The Kardia Band has the electrodes embedded on the
underside and on top of the band.