Long QT

I am a methadone patient and have been told by the clinic that since I am on what they consider a high dose 175mg daily that I need an EKG.  I have been on methadone at this level for 12 yrs with absolutely no problems.  I went to the VA and got an EKG now they say that since the QTc intervals are 500ms that I am subject to SCD or Torsades de pointes.  I have had Bradycardia all of my life even before taking methadone.  I am 58 yrs old in excellent health. I walk run 5 miles daily and workout on the treadmill after that on an incline then work with weights for about 2 hours...all almost daily.  I have never had any palpitations or tachycardia or chest pains or anything..blood pressure is great and all my blood work is within the normal levels for everything Cholesterol and Triglycerides are excellent.  They are using a report issued this year that is really inconclusive.  They state methadone causes the long QT and I could possibly experience Torsades de pointes but since I have had bradycardia all my life I know it is not the methadone causing it.  Is the 500ms on the EKG a potential problem for me given all the info above??