From WebMD
“Beta-blockers are a class of drugs used to control symptoms of heart failure that are made worse by certain hormones called catecholamines. The body releases these hormones as part of its response to heart failure. For this and other reasons, beta-blockers have been shown to be effective for treating most people who have heart failure.
Beta-blockers may work by slowing the heart rate, which allows the left ventricle (the main pumping chamber of the heart) to fill more completely.
Some of these medicines may also help open or widen blood vessels in the body. This makes them especially useful in some people with certain forms of heart failure who may also have high blood pressure.
Bisoprolol, carvedilol, and metoprolol are some of the beta-blockers that have been tested for use in the treatment of heart failure.”
http://www.webmd.com/heart-disease/heart-failure/beta-blockers-for-heart-failure