Hello, My question is having been on toprol (generic is metoprolol) 12.5 mg for exactly a year now, I have a question lately I have felt like my heart is beating weaker or something to that degree, now as I do suffer from a very severe anxiety disorder it could simply be all misconception. But If there are any Dr s or RN s I would like to know if Beta blockers weaken the Heart muscle or its ability to pump blood. And could it also be a side effect of my being afrad of heart problems (im on it for anxiety symptom reduction and because my heart rate was reaching 170 180 durning attacks for maybe 3 hours) And because of these fears I do not exercise at all I have not since the summer of 07 I also take xanax as needed. (22 1/2 years old dont smoke drink etc) Thank you very much. 12.5 mg once per day forgot to add that my apologies.