What cough medicine is best for patients that have chf congestive heart failure?

None, really: Coughing is related to having fluid in the lungs. It is not going to respond to a cough suppressant or expectorant. It responds to diuretics, which help to remove the fluid from the lungs.

No perfect answer: Probably best to avoid combination medicines which contain pseudoephedrine, which many do. This speeds up your heart. Diphenhydramine (benedryl) can dry up secretions. However, it is important to understand that the cough may be due to the chf. Also medications commonly used to treat CHF (ace inhibitors - often end with ..Pril) can sometimes cause a chronic dry cough. Talk to your md.