Best thing you can do is to journal your symptoms and tell your doctor about them...even these odd little things that may seem weird or insignificant can help him to to better treat you. IST is usually treated in much the same way. But it needs to be documented, which is usually very easy if hooked up to EKG in the office and then asked to perform various actions like talking, moving, and even stepping up/down off the exam table step (this is how they Dx mine).

It all depends on how significant it is as for how they treat it. A minor adjust in meds or sometimes adding a different class of meds can help.

I'm sure your electro is well aware of IST, but hasn't heard you mention some of these odd times that you experience increased heart to look for IST. They can also use event recorders or holter monitor to document the errant heart rates.