Long QT for rate

Female, 32,No current regular medication.

I hope it is ok to post in this group.  There is no longer a posting feature for the Heart Rhythm expert forum. For the last two years (since I briefly tried a tricyclic for neuropathic pain) I have had frequent tachycardia. I stopped taking the drug when my heart rate was caught at 200bpm resting but, while things improved a little, I still get the frequent unexplained tachycardia.  I've always gotten light headed and dizzy with exercise, which I have always assumed was due to low blood sugar or something.
Since my tachycardia, I have had ecg's and a stress test.  I was not taking any medication around this time. On the day of my stress test my baseline ecg showed at heart rate of 122 bpm and a qtc of 591.  My post stress test ecg showed a heart rate of 183 and a qtc of 478.  No one mentioned anything about this but I have seen that the ecg's say "qtc long for rate".  This seems to be the case on any ecg's I have where my heart rate is elevated.  I have been discharged from my doctors care with the diagnosis that my tachycardia is caused by my small stature (5’0, 85lbs) and is simply being noticed now for the first time.  Before I accept that (it seems strange given that there was an onset to symptoms), I would like to be sure there is nothing about this "Long QT for rate" that I should be concerned about.  I just don't know if I trust my doctors assurances that there is no unsafe upper limit to my heart rate.  He says that because my baseline is so high, I will go up much higher than average.  This may be true but I want to be satisfied. Is this high QTc for rate something of concern?  Should I be bothering to look into in when I’ve already been discharged?  Here is a link to my Pre and post test ECG's, which I have scanned and added to my home page:
http://www.medhelp.org/user_photos/show/115422?personal_page_id=459431
and http://www.medhelp.org/user_photos/show/115421
Thanks for your time!

[Lee Kirksey, MD]

Hello
Thats a great idea to scan the ekgs. A couple things. It seems odd that your stature has always been the same (I assume) but for unclear reasons you have had symptomatic tachicardya for two years only. I assume that you feel the episodes and the fact that you did not notice them prior to this period suggests to me that they were not present. Additionally, the lightheadedness with exertion is not typical

Electrical disturbances are a specific subspecialty because of their complex number of causes and factors which affect their development. To that end, if you are a little uncomfortable with attributing this purely to your body habitus (I am)- I would seek out a second opinion from an conduction system specialist. They might consider other tests like a tilt test, stress echo or holter monitors

They may come to a similar conclusion but at least youll have the peace of mind that two experts agreed. Make sure that you accumulate all of your records and go to your regional expert in arrhythmia.

Good luck