May 30, 2017

Atrial Fibrillation (AF, AFib)

What are the treatment guidelines for atrial fibrillation?

The treatment of atrial fibrillation is multi-faceted and involves:

  1. Reversing the factors that cause atrial fibrillation.
  2. Slowing the heart rate with medications.
  3. Preventing strokes.
  4. Converting atrial fibrillation to a normal heart rhythm with medications or electrical shock.
  5. Preventing the recurrence of atrial fibrillation with medications.
  6. Using procedures (for example, pacemakers, defibrillators, surgery) to prevent episodes of the disease.

Reversing the risk factors (drugs or other diseases or conditions) that cause atrial fibrillation

An important first step in the treatment of AF is to uncover and correct health conditions (such as hyperthyroidism or use of stimulant drugs) that can cause the disease. These steps include:

  • Stopping the use of stimulant drugs and excessive alcohol intake
  • Controlling high blood pressure
  • Correcting hyperthyroidism (too much thyroid hormone) and low blood oxygen levels
  • Controlling cardiac failure and treating the diseases of the heart and the lungs that can cause atrial fibrillation

Drugs that slow the heart rate

Available medications to slow heart rate

Having excluded or corrected the factors that cause the disease, the next step is when the ventricles are beating too rapidly, usually is to slow the rate at which the ventricles beat.

A person with the disease and healthy AV nodes usually have ventricles that beat rapidly. Drugs are necessary to slow down the rapid heart rate. Drugs to slow the heart rate include:

  • digitalis (Digoxin)
  • Beta blockers such as propranolol (Inderal), atenolol (Tenormin), metoprolol (Lopressor), esmolol (Brevibloc)
  • Calcium channel blockers such as verapamil (Calan), diltiazem (Cardizem)

These medications slow the heart rate by retarding conduction of the electrical discharges through the AV node. These medications, however, do not usually convert AFib back into a normal rhythm. Other drugs or treatments are necessary to achieve a normal heart rhythm and improve health.

Benefits of controlling the rate: In patients with rapid ventricle contractions as a result of the disease, slowing the rate of ventricular contractions improves the heart's efficiency in delivering blood (by allowing more time between contractions for the ventricles to fill with blood) and relieves the symptoms of inadequate flow of blood -- dizziness, weakness, and shortness of breath.

With chronic, sustained disease, doctors may decide to leave some patients in atrial fibrillation provided that their heart rates are under control, the output of blood from theventricles is adequate, and their blood is adequately thinned to prevent strokes. This form of treatment is called rate control therapy (discussed in this article).

Limitations of medications for controlling the heart rate: In people with diseased AV nodes, ventricular contractions may be slower than in those who have normal AV nodes. Moreover, some elderly individuals with atrial fibrillation are extremely sensitive to medications that slow the rate of ventricular contractions, usually because of a diseased AV node. In these patients, the heart rate can become dangerously slow with small doses of medications to slow the heart. This condition is referred to as tachycardia-bradycardia syndrome, or "sick sinus syndrome." Patients with tachycardia-bradycardia syndrome need medications to control the fast heart rate and a pacemaker to provide a minimum safe rate.

Drugs used in slowing atrial fibrillation generally cannot convert atrial fibrillation to a normal rhythm. Therefore, these patients are at risk for the formation of blood clots in the heart and strokes and will need prolonged blood thinning with anticoagulants like warfarin (Coumadin, Jantoven).

Risks and candidates for cardioversion

What are the risks of electrical cardioversion?

The complications of cardioversion include stroke, burns of the skin, and in rare instances, death. However, these problems are very uncommon.

Who are candidates for electrical cardioversion?

Doctors usually recommend that all patients with chronic, sustained atrial fibrillation undergo at least one attempt at cardioversion. Cardioversion usually is attempted with drugs first. If medications fail, electrical cardioversion can be considered. Sometimes a doctor may choose to use electrical cardioversion first if AF is of short duration (onset within 48 hours) and the transesophageal echocardiography shows no blood clots in the atria.

Cardioversion is performed urgently (on an emergency basis) on patients with severe and potentially life-threatening symptoms caused by AFib. For example, some patients with rapid AF can develop chest pain, shortness of breath, and dizziness or fainting. (Chest pain in these patients is due to an insufficient supply of blood to the heart muscles. Shortness of breath indicates ineffective pumping of blood by the ventricles. Fainting or dizziness usually is due to dangerously low blood pressure.)

What is rate control therapy?

Recent studies have shown that an acceptable alternative to cardioversion (chemical or electrical) is rate-control therapy. In this therapy, the doctor will leave the patients in AF provided their rate of ventricular contractions is under good control, the output of blood from the heart is adequate, and their blood is adequately thinned by warfarin to prevent strokes. Heart rate in these patients can be controlled using medications such as beta blockers, calcium channel blockers, or digoxin or AV node ablation with pacemaker implantation. Rate-control therapy is used to simplify therapy and avoid the side effects of anti-arrhythmic medications (medications used to treat and prevent atrial fibrillation).

Over long periods of observation, patients treated with rate-control therapy have similar survival and quality of life as compared to those who undergo repeated electrical or chemical cardioversions.

Suitable candidates for rate-control therapy include:

  • People who have had atrial fibrillation for more than one year
  • Individuals with significant disease of the heart valves
  • People with enlarged hearts as a result of heart failure or cardiomyopathy (heart muscle weakness)
  • Patients with significant or intolerable side effects with drugs used for the condition.
3/7
Reviewed on 1/30/2017
Atrial Fibrillation Quiz