A lot of us approaching , say 60, routinely have ECG's taken and get alarmed when a change is detected in his.
It has been found that if you take thyroid medication levothyroxine, this sometimes shows up in the form of some changes in your ECG. So it is important, that you inform the doctor about your medications when going in for a test like an ECG.
For a rigorous treatment of this subject, please see this
2 weeks ago