What Exactly is Borderline LQT Interval?

So many studies give differing values for borderline LQTS and for one whose QT interval lies between to two outer values it is very confusing. I see an EP next week but in the meantime with each article/study I read I find myself one minute hopeful and the next worried. I had an ECG yesterday at my GP’s office which showed prolonged QT intervals of 453ms and 469ms. My GP was not worried (though she referred me to EP to be sure) and she described the results as mild. I also have low potassium and am on a diuretic (Dr. thinks this is causing the low potassium).

However some studies put borderline LQTS at between 440ms and 470ms and others at between 440ms and 460ms so I am really confused. I have no symptoms (fainting etc) except palpitations which have been assessed by my EP and found to be of no concern. I also have no family history of cardiac arrest/sudden death with  all aunts and uncles, of which I have several, and parents well over 70year of age.
Is there a risk of cardiac arrest or sudden death at QT intervals of 469ms?

Thanks for your answers.

[heart_of_mine]

I have Long QT Syndrome. Your QT intervals are considered borderline for a woman. Some women have intervals up to 470+ and are still considered normal. Diagnosis of LQTS is based on more than just QT intervals. It is possible that your low potassium could be causing this mild prolongation. It is good that you have no family history consistent with sudden death or no symptoms. Risk assessment in LQTS is an educated guess at best for most EPs but QT intervals over 500 usually mean a higher risk for cardiac events but there are no steadfast rules.
If I were you I would get my potassium up a bit by eating bananas etc before your visit to the EP and try not to worry too much.