does my levoxyl effect atenolol?

THANKS so much for the forum.I have tried for 3 months to get on. Female, 38 yrs. old, work out 5 times a week, non smoker, cafeeine, non drinker. Normal b.p.  I am on Levoxyl .175 for hypo.thyroid due to graves disease treated with the radioactive iodine.  Have been on it for 8 years. Blood work 6 mos ago was normal. Always had a few PVC's in last 10 years,with pregnancy especially, but last 6 weeks they are really bothersome. This was the time of a GREAT increase in stress with new job, a difficult family situation, etc,etc. Couldn't sleep because of hours of them. Dr. re-did a holter, EKG, stress test and was told I had a fine heart. All were benign, but put me on 25 mg atenolol/day  so I could sleep. For about a week I felt great, then they were back in the day. He increased to 50mg each night but said no higher.  I felt great for 6 days, now they are bad again off and on in the day. I don't want to go higher because I feel sluggish in my workout, can't get my heart rate up. Pharmacist told me levoxyl might affect atenolol but had no more info just"maybe".Can't find info on line and I can only see my fam.Dr.due to insur.My Dad at 68 had constant arrhythmia, meds didn't work and he was "shocked back" into regular rhythym. Both grandmas had PVC's. 1.Does levoxyl affect atenolol? Would another beta blocker work or do some people just get used to them and they don't work?
2.Will I become like my Dad? Right now would the shock be for me? 3.Is it genetic to have these benign stress triggered PVC's? 4. Still cardio benefit on beta's with low h.r? I AM THANKFUL FOR YOUR HELP!

[CCF-M.D.-CRC]

Dear jjill,
I'm glad you finally made it on after 3 months!  The answer to your first question is no, levoxyl does not affect atenolol.  I think what your pharmacist may have been thinking about is the levoxyl affecting the PVCs.  If you are on too high a dose of levoxyl it may increase palpitations.  It is important to have regular blood tests of your thyroid levels to insure that your doseage is not too high or too low.  

2. You dad has a different rhythm called atrial fibrillation.  This is a common rhythm and you can find more information about it on this website.  PVCs do not lead to atrial fibrillation.

3. There are some rare conditions where PVCs may be genetic but for most people they are not inherited.

4. Beta-blockers do decrease PVCs but a potential side-effect is low heart rate and fatigue.  If the heart rate or fatigue are too severe then the dose must be decreased or stopped.   For individuals with heart attacks beta-blockers decrease the risk or death and another heart attack.  For individuals with only PVCs the benefit is only symptom relief.