I Had My Thyroid Removed Dec 8 2016. Before Removal

I had my thyroid removed dec 8 2016. Before removal my tsh was 0 and t4 was 16 plus. After removal tsh was 15 and t4 was 0. Started taking 75mcg of levonthyroxine. Blood work 6 weeks later show tsh at 58 and t4 at 0.5. I have a history of heart problems, afib issues and a pace maker. What problems could I have with so high of a tsh level? My doctor just increased my levonthytoxine to 137mcg. John T.