Toprol XL (metoprolol) is another drug in the family of beta-blockers. There is some data that it is equally effective in heart failure. In addition it is a once-a-day drug. However, in my experience the side-effects of beta-blockers are similar across all of the different types. However, it may still be worth a trial. I would discuss this with your doctor and see if he/she agrees.
I have been taking heart meds for over three years. One year ago, my cardiologist switched me from coreg to toprol xl. My ef a year ago was in the 25%+ range. It took a while for me to adjust to the dizziness, etc. associated with twice a day doses of coreg, but I was really feeling pretty good at the time I changed over to Toprol. With the once a day 40 mg dose of Toprol, I felt really bad in the morning until thirty minutes or so after taking my daily Toprol xl tablet, and felt dizzy between 7-8 pm (about half way through the 24-hour Toprol time release phase). My most recent echo yielded an ef of 15%. My internist suggested that I cut my 40 mg Toprol xl tablets in half and take one half in the morning and half in the evening to alleviate the evening dizziness and morning tiredness. I have been taking half-doses twice a day for a couple of weeks and that seems to help. I am now scheduled for another test with a CHF specialist to evaluate my condition with potential to be placed on a waiting list for a heart transplant (due to my low ef and apparent declining heart strength). I plan to ask the CHF specialist to change me back, from Toprol xl to coreg.