Interpretation of an ECG is no simple matter.

There are 100s of patterns to recognize.

It may be impossible to tell how long an abnormality has been present.

This issue becomes crucial in an emergency situation when a person has symptoms consistent with a heart problem and an abnormal ECG.
Some or all of the abnormalities may have been caused by an event long in the past and unrelated to the current situation.

Some people are even born with ECG abnormalities.

This can make it difficult to identify which problems require urgent treatment.

This is the equivalent of examining a car that has been in both a recent car accident and accidents in the past. Which dents were caused by which accident?
For these reasons, if you have either a heart condition or an abnormal ECG, you would be wise to keep a recent copy of your ECG handy in your wallet, purse, or car glove compartment for immediate availability.

This way you will be able to provide your baseline ECG to a very grateful emergency care provider in case you unexpectedly end up in an emergency department, especially in the middle of the night or far from home.

A copy of your ECG can be shrunk to credit card size and laminated to be carried in your wallet. If you have an abnormal ECG or you travel a lot, ask your health care provider about doing this for you.