One of the most frightening aspects about having
heart failure is that it can lead to premature death.
The increased death rate among people with heart failure is in part caused by
the tendency of those with heart failure to develop
abnormal heart rhythms.
Some people with
heart failure die suddenly from abnormal rapid heart rhythms (called
ventricular tachycardia or ventricular fibrillation) that begin in the damaged
muscle of the heart. These abnormal rapid heart rhythms are dangerous because
they start without warning and dramatically reduce the heart's ability to pump
blood. If the abnormal rhythm does not stop on its own after a short period of
time, death results from reduced blood flow to the brain and vital
organs.
What antiarrhythmic agents are safe and effective? Finding safe antiarrhythmic drugs for people with heart
failure is an active area of study. Currently only two medicines are clearly
safe and effective for the prevention of ventricular arrhythmias in people with
heart failure:
Beta-blockers have been proved to increase the survival of
people with heart failure. It is not entirely clear how this occurs, but it is
suspected that a major factor is their ability to prevent ventricular
arrhythmias. Beta-blockers can be very effective at preventing single abnormal
beats of the heart muscle, called premature ventricular contractions, which
experts think are a common trigger of ventricular arrhythmias. These beneficial
effects have been observed for essentially all beta-blockers. The ability of
beta-blockers to prevent ventricular arrhythmias further emphasizes why all
people with heart failure should be taking them.
Of equal
importance, beta-blockers do not have any proarrhythmic effects, even in people
with very abnormal left ventricular function. When a medicine increases the
occurrence of arrhythmias, it is said to have a "proarrhythmic" effect.
Amiodarone is an antiarrhythmic medicine that has been extensively
studied in people with heart failure. Amiodarone may not be useful for everyone
with heart failure. Although amiodarone may prevent abnormal heart rhythms, it
has not been shown to lengthen the lives of people with heart failure.1 Also, amiodarone has many side effects. Your doctor will help
you decide whether taking amiodarone is right for you. Your heart rhythm may be
monitored continuously for a 24- or 48-hour period using a Holter monitor. If
you take amiodarone, you will need to see your doctor periodically to determine
whether you are developing any side effects.
You may take
amiodarone if you have an
implantable cardioverter-defibrillator (ICD), a device
that is implanted in your chest to control your heart rhythm. This device is an
alternative to or an addition to antiarrhythmic medicines such as amiodarone.
Amiodarone is used so that you will need fewer shocks from the ICD to control
your heart.
In addition to these medicines, you can reduce your
risk of life-threatening arrhythmia by maintaining adequate blood levels of
potassium, magnesium, and calcium. Deficiencies of these
electrolytes can increase your risk of ventricular
tachycardia. Ask your doctor about monitoring the levels of these electrolytes
in your blood, particularly if you change the doses of your diuretic
medicines.
