Hey there, just saw your post.
I think a QT interval of 487 sounds a little long but I have to ask... what was your Cardiologists response to this? A prolonged QT interval isn't always something of concern. Sometimes the electrical system in our hearts is "off" and causes a long QT and sometimes medications can be the cause.
You should take a look at a list of medications that cause it. A lot of different meds can cause it.
As far as worrying about it, relax. I imagine you and your cardio doc talked about it and whatever symptoms you are having which caused him/her to check an EKG in the first place. I guess the best advice I can think of is to make sure you ask a lot of questions and always leave your visit with a clear plan. In other words are you just going to continue to call the office if you have recurring symptoms? Are there follow up tests? Follow up visits with your doc in the future? You get it, what's the "plan"?
Best wishes
M
There are blood tests for genetic long qt syndromes and many meds pro long qt readings
Sorry, I hit send to soon. I was going to say in summary that there is a lot that goes into all of this. Just remember, you want a good doctor, but need to be a good patient too. This means getting your facts straight, and from the right source (ie your doctor, usually).
The measurements have to be corrected from their raw value. I am not a doctor and know nothing about it. I think there is probably more than one way to do it.
Also, it is possible to blend other sources of information with the ecg when making the diagnosis. For instance, genetic markers of they are known.