Although beta blockers were once contraindicated in congestive heart failure, as they have the potential to worsen the condition, studies in the late 1990s showed their positive effects on morbidity and mortality in congestive heart failure.   Bisoprolol, carvedilol and sustained-release metoprolol are specifically indicated as adjuncts to standard ACE inhibitor and diuretic therapy in congestive heart failure.
The beta blockers are a benefit due to the reduction of the heart rate which will lower the myocardial energy expenditure. This is turns prolongs the diastolic filling and lengthens coronary perfusion. Beta blockers have also been a benefit to improving the ejection fraction of the heart despite an initial reduction in it.
Trials have shown that Beta blockers reduce the absolute risk of death by 4.5% over a 13 month period. As well as reducing the risk of mortality, the number of hospital visits and hospitalizations were also reduced in the trials.