Long QT -- Only 1 abnormal cardiogram, can I ignore it?

Hi there,
I've had heart flutters for pretty much my entire life, never last more than a few seconds.
Anyhow, in a routine pre-surgical check-up (surgery was unrelated) at Mount Sinai Hospital in NY, I was given a cardiogram and the doctor said I had Long QT syndrome and I needed to have it taken care of once I'd recovered from surgery. Then a cardiologist looked at my results and said I'd also have to stop taking Effexor for my depression.
However, when I did follow up with my internist, also at Mount Sinai, who gave me another cardiogram, the irregularity didn't show up and she said to ignore the first cardiogram since my physical indicated I had an otherwise extremely low risk of heart attack.
I do hope she's right because my depression is severe, recurring, and treatment resistant. Despite trials with everything other drug out there, singly and in combination, effexor is the only thing that has ever worked. (Plus, with severe ad/hd, last thing I need is the brain-fogging beta-blockers they prescribe for Long QT).
On the other hand, I'm a bit concerned about ignoring it, because the cardiologist was so emphatic I shouldn't, and because there are times when my dosage of effexor gets ramped up to four 150 mg capsules a day and my heart flutters quite a lot.
Thank you in advance for any insight you can provide!
Amy
btw, I'm 51, thin to ordinary weight, and I do have hmo health insurance but benefits are very poor.