Thread by @netta_doc

The countdown to #ACC19 has begun!

Here’s a THREAD about the much anticipated #AppleHeartStudy

(results to be presented at 9am THIS Saturday, March 17 at #ACC19 by #EPeeps Mintu Turakhia AKA @leftbundle from @SCCR_Stanford!)

#ACCEP

The #AppleHeartStudy aimed to test the ability of a smartwatch algorithm to detect an irregular pulse consistent with AF, & to estimate its diagnostic yield in a large population:
#ACC19 #ACCEP

The cool thing about the #AppleHeartStudy, is that all of it was done virtually. ALL. OF. IT. Enrollment, consent, study visits, patch monitoring. Here are the #AppleHeartStudy ‘s main objectives in detail:
#ACC19 #ACCEP

Enrollment:

* Download #AppleHeartStudy App
* Self-verify eligibility, sign consent digitally on iPhone touchscreen
* Do demographic & medical history questionnaire
* 24 hr telephone number for questions/ more info/clarifications available at all times
#ACC19 #ACCEP

The inclusion/exclusion criteria for #AppleHeartStudy were also pretty straightforward:
#ACC19 #ACCEP

Here is the #AppleHeartStudy design algorithm in its entirety, which we will look at in sections:
#ACC19 #ACCEP

#AppleHeartStudy
The #AppleWatch measures pulse via photophlethysmography.

What the heck is PHOTOPHLETHYSMOGRAPHY?
(Basically #LED or #Infrared light is used to measure differences in blood flow to estimate pulse)

See here how it’s done:

#ACC19 #ACCEP

#AppleHeartStudy
What is a tachogram (pulse rate/time)?

* LED lights & photodiodes measure changes in wrist blood flow to create a photoplethysmogram (PPG) (pulse estimation)
* Time between PPG signal peaks (intervals between pulses) are used to create a tachogram
#ACC19 #ACCEP

#AppleHeartStudy didn't use #ECG which is done like this:
•Make sure the #AppleWatch is snug on your wrist
•Open the ECG app
•Rest arms on a table/your lap
•Hold finger on Digital Crown for 30 sec to record
•Add symptoms, tap Save & Done
#ACC19 #ACCEP @ACCinTouch

Back to the #AppleHeartStudy protocol. If a normal tachogram was detected, NBD, study ended and patient filled out the end of study questionnaire
#ACC19 #ACCEP

#AppleHeartStudy

If abnormal tachograms were detected, the watch/app notified the pt, virtual study visits occurred & the study participant got to wear an ambulatory ECG patch (“ePatch”) which then got analyzed. Care was based on the outcome of the ePatch
#ACC19 #ACCEP

Here are the 1*, 2*, and 3* endpoints of the #AppleHeartStudy in detail:

#ACC19 #ACCEP

And the limitations of the #AppleHeartStudy here:
#ACC19 #ACCEP

In case you wanted to read the #AppleHeartStudy rationale & design yourself, here’s the link:
sciencedirect.com/science/articl…

#ACC19 #ACCEP

Results of the #AppleHeartStudy are coming soon - stay tuned for more on Saturday!

#ACC19 #ACCEP

~fin~