Reentrant tachycardia symptoms and conditions

Hello to you all. I have been on Toprol XL for 8-10 months. I have "palpitations" which is why I was placed on this med. Also a diagnosis of Mitral Valve Prolapse. My doctor told me that the MVP can trigger the palpitations and that Toprol is the drug of choice. It helped for a few days. I felt like a new person at first. Then the palpitations gradually started to come back. I have gained 10 lbs. I am 50 years old and assumed that my wt gain was menopause. Now I think that is NOT the answer. I am an RN and I intend to wean myself off of the Toprol after reading the messages here! Why do I need to keep taking a medicine that is causing me to get fat and is NOT controlling my symptoms? Good luck to you all.