When your heart begins to fail, your body tries to
compensate for decreased blood flow by stimulating the heart to pump faster and
more forcefully. Your nervous system does this by releasing a chemical called
epinephrine into your blood and by releasing norepinephrine from nerve endings
on the heart. At first, these chemicals (epinephrine and norepinephrine)
increase the pumping action of your failing heart. But eventually increased
levels of epinephrine can actually make your
heart failure worse, probably by causing damage to the
heart muscle cells over time.
Beta-blockers work by blocking the
action of epinephrine and norepinephrine to slow your heart rate and reduce the
strength of each contraction. Beta-blockers may actually cause your symptoms to
get worse at first. But in the long term, beta-blockers can prevent worsening
of heart failure and, in some cases, improve heart function. These medicines
may also block the development of serious irregular heart rhythms and lower the
risk of sudden death.
Because the beneficial effects of
beta-blockers are so clear, doctors are more consistently prescribing them for
all types of heart failure. Beta-blockers are considered a first choice in drug
treatment for heart failure, along with diuretics and angiotensin-converting
enzyme (ACE) inhibitors.