08/10/2025
One of my juniors asked me the other day:
"Is ECG on Apple Watch real?"
The answer is...
"Yes. It's real and it's reliable."
Apple Watch uses two electrical sensors to replicate the Lead I of an ECG machine.
One sensor is in touch with the hand that's wearing the watch.
The other sensor is on the digital crown, and it has to be in touch with the finger of the other hand.
The drawback is that it only has one lead.
ECG can only be properly interpreted when there are 12 leads.
Looking only at Lead I is like looking at the heart's electrical activity from only one perspective.
However, Lead I can give you important information like rate, rhythm, any block, and even ST and T changes.