Why would a Dr need 2 ECGs to compare to each other

[TodaysFishIsTroutALaCreme]

Stuck in A&E with DD who has chest pains. She had one ECG and then was called back an hour later as the doctor wanted another to compare to the first one.

I am not particularly worried. If it was something serious the doctor would have seen us but I was just wondering why the two ecgs were needed.

As they said, to compare them. Have symptoms improved/worsened/stayed the same?

Hope everything is sorted soon and you can both get rest.

Yeah, I guess it was a bit of a daft question. I was just wondering if they had found something to concern them which us why they asked for a 2nd one.

It's been a loooong night so far. The worst of the pain has abated but there is still underlying discomfort

An ecg only shows a snapshot of your heart activity at the exact time it was taken (I’m a nurse) so if anything changed minutes after you’d miss it so will just be to see if anything is different, not necessarily a bad sign

Thank you. Being bored and Dr Google is never a good idea 😁

Sometimes it’s the placement of the leads, any movement or even just a part of the line that’s not clear.
or taking a breath at the wrong moment,

All very reassuring. Thank you