I recently ended up in the ER with changes on the stress test. I have been changed to the drug Coreg because of problems with Toprol XL I am concerned about taking 6.25 mg twice a day, because I have problems with Toprol XL at a low dose. I seem to have problems with heart medicines. I do fine with nitro patch. I had open heart surgery 3 years ago, and grafts had filled up 50% 2007. I also had the aortic valve replaced. My tricuspid and mitral valve regurgitate. The main problem is I have lots of blockages that they can't seem to address. As of yesterday I have been told to only go 2.4 on a treadmill and to e-mail the doctor everyday. I have been having unstable angina as well as stable angina that has increased. My main question is to know how Coreg affects someone.