Medicines to Prevent Abnormal Heart Rhythm in Heart Failure
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.
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