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Atrial Fibrillation (AFib) vs. Ventricular Fibrillation (VFib) Causes. Which Is Worse?

Reviewed on 1/8/2019

Atrial Fibrillation vs. Ventricular Fibrillation Related Articles

What Is Atrial Fibrillation (AFib)?

Atrial fibrillation (AFib) is a type of abnormal heart rhythm (arrhythmia), usually with a very fast heart rate, that is caused by irregular contractions of the upper chambers of the heart (the atria).

What Is Ventricular Fibrillation (VFib)?

Ventricular fibrillation (VFib) also is a type of abnormal heart rhythm in which the heart rate that is irregular, and usually fast due to irregular contractions of the lower chambers of the heart (ventricles).

Are AFib and Vfib Caused by the Same Problem?

Atrial fibrillation and ventricular fibrillation are caused by similar problems with the heart, but they are not the same type of problem. Electrical impulses generated within the heart tissue cause both heart conditions, but the electrical impulses arise in different areas of the heart. Irregular electrical impulses occur from multiple sites in the atria to cause atrial fibrillation, while irregular electrical impulses occur mainly in the ventricles to cause ventricular fibrillation.

Which Is Worse, AFib or VFib?

Although both atrial fibrillation and ventricular fibrillation may cause serious medical problems with a patient. Ventricular fibrillation, especially if it is sustained, is considered far more serious as the patient can quickly develop "sudden death" or "cardiac arrest," and die. Ventricular fibrillation does not allow the heart to pump enough blood to the arteries, and therefore to the body's vital organs, because the heart's ventricles are quivering (fibrillation), and they cannot pump blood (contract or squeeze). Ventricular fibrillation is considered a medical emergency.

ECGs and Pictures of AFib vs. VFib

Pictures of a normal and a fibrillating heart, and its electrical activity during atrial fibrillation.

Picture of a Cross Section of the Heart Including the Atria and Ventricles.
Picture of a Cross Section of the Heart Including the Atria and Ventricles.

AFib also is referred to as "supraventricular tachycardia" because the problem occurs above the ventricles. In AFib, the abnormal heart rhythm is due to irregular electrical activity in the atria, mainly the right atrium, and usually it results in a fast and irregular heartbeat.

Picture of a Normal Heart, and a Heart During Atrial Fibrillation

The electrical activity of a normal heart, and a heart during atrial fibrillation.

VFib occurs when the electrical signal is chaotic within the ventricular muscular tissue, which results in no effective heartbeat so there is no effective blood pressure or pulse generated, which results in sudden cardiac death if the person is not treated immediately.

Picture of the Electrical Activity of the Heart during Ventricular Fibrillation.
Picture of the Electrical Activity of the Heart during Ventricular Fibrillation.

ECGs of a normal, atrial fibrillation, and ventricular fibrillation

Normal ECG Wave Pattern Strip of a Normal Heartbeat

Normal ECG Wave Strip Pattern
Normal Heartbeat ECG Wave Strip Pattern

Enlargement of a normal ECG Strip showing PQRST Intervals in a normal heartbeat

Enlargement of a normal ECG Strip showing PQRST Intervals in a normal heartbeat
Enlargement of a normal ECG Strip showing PQRST Intervals in a normal heartbeat

ECG EKG Wave Strip of Atrial Fibrillation

Atrial Fibrillation ECG Wave Strip Pattern
Atrial Fibrillation ECG Wave Strip Pattern

Note in the strip above, AFib ECG irregular waves that separate the QRS complex resulting in an irregular heartbeat seen as the QRS complex spikes.

The following figure shows Vfib with no QRS complex spikes. This means there is no effective ventricular contractions which means the is no heartbeats- the heart muscles of the ventricles just twitch or shake.

ECG Wave Pattern Strip for Atrial  Ventricular Fibrillation

ECG Wave Pattern Strip for Atrial Ventricular Fibrillation


See Images

Which Signs and Symptoms of AFib vs. VFib are Similar?

Both ventricular and atrial fibrillation may cause dizziness, nausea, shortness of breath, and chest pain. However, some people with VFib may only experience these symptoms an hour or so before a sudden collapse. People with AFib may experience the signs and symptoms for various periods of time (minutes, hours, days) without a sudden collapse.

Which Signs and Symptoms of AFib vs. VFib Are Different?

Ventricular fibrillation usually has a very short time frame of profound signs and symptoms such as collapse, loss of consciousness, and either a weak, erratic pulse or no pulse at all.

In contrast, atrial fibrillation can produce a number of symptoms that can occur over prolonged periods, for example:

  • Irregular and rapid heartbeat or pulse
  • Weakness
  • Dizziness
  • Fatigue (especially with any exercise)
  • Feeling like you’re going to faint
  • Occasional confusion
  • Thumping or fluttering in the chest

How Are AFib vs.VFib Treated and Managed?

Ventricular Fibrillation Treatment and Management

VFib is a medical emergency. It must be treated immediately if the person is to survive.

Cardiopulmonary resuscitation (CPR) needs to be started immediately to help maintain some blood flow to the body.

As soon as possible, the delivery of electrical shock (defibrillation) needs to be done to attempt to allow the heart to resume a normal rhythm. Some public places like shopping malls and public buildings may have AEDs, or automatic external defibrillators available for such emergencies. Individuals that survive ventricular fibrillation will likely need medications and an implantable cardioverter-defibrillator (ICD), and evaluation for surgical stint placement, surgical coronary angioplasty, or bypass surgery.

Atrial Fibrillation Treatment and Management

AFib may be treated with medication, simple procedures, or surgery.

Medications like beta blockers and calcium channel blockers (CCBs) help improve symptoms, but do not cure abnormal electrical impulses. Moreover, because of the chance of developing blood clots is increased with AFib, anticoagulants usually are prescribed.

Simple procedures such as avoiding foods that may trigger AFib (for example, caffeine containing liquids like coffee) is helpful.

Some people with AFib respond well procedures like electro-cardioversion. This technique is used to reset the heartbeat to normal, but uses far less electricity than is used for fibrillation. Ablation techniques (for example, radiofrequency ablation, laser ablation or cryo- ablation) can be used to diminish or destroy areas in the atria that function as sources for abnormal electrical signals.

Some individuals may benefit from surgery to implant a pacemaker, which generates an electrical signal to keep a steady rhythm in the heart, or to sense when the heartbeat is too fast or too slow, and then provide appropriate electrical intervention.

Can AFib vs. VFib be Prevented?

Reducing the risk of AFib and VFib is done by regular physical activity, heart healthy diet, managing high blood pressure, and avoiding alcohol and stimulants like caffeine and/or nicotine.

You can reduce recurrent episodes of AFib by controlling your blood pressure and by taking prescribed medications for underlying medical conditions (for example, thyroid disease, diabetes, obesity) you have.

In VFib, an implanted device (ICD) can automatically defibrillate the heart if it detects the arrhythmia. However, it does not prevent the condition. The device is only designed to automatically stop intricate fibrillation after it occurs.

What Is the Outlook and Life Expectancy for AFib vs. VFib?

The outlook for a person with untreated ventricular fibrillation is poor. The individual usually will die within a few minutes if untreated. Even if VFib is treated, survival rates at best range from about 20%-35%. Rates are higher if the person is taken to the hospital immediately and receives medical care. Many people that survive ventricular fibrillation have some level of neurologic damage.

In general, individuals with atrial fibrillation, if appropriately treated, can live a relatively normal lifespan, depending on other heart disease problems. However, the condition increases the chance of having a stroke and/or heart failure, especially if not treated.


In the U.S., 1 in every 4 deaths is caused by heart disease. See Answer

What Are Other Names for Atrial Fibrillation and Ventricular Fibrillation?

Atrial fibrillation and ventricular fibrillation are written in many different ways in literature. Some examples include:

  • Ventricular fibrillation, Ventricular Fibrillation, vfib, Vfib, VF, vfib, v-fib
  • Atrial fibrillation, Atrial Fibrillation, afib, Afib, afib, a-fib, and AF, sometimes atrial fibrillation is referred to as “holiday heart syndrome,” as excess short term use of alcohol can set cause the condition.

Note: Atrial fibrillation’s designation as “AF” is easily confused with another heart arrhythmia, atrial flutter. Unfortunately, atrial flutter also is abbreviated or written as “AF.” Atrial flutter is a heart arrhythmia closely related to atrial fibrillation.

Health Solutions From Our Sponsors

Atrial Fibrillation Warning Symptoms and Signs

Atrial fibrillation or AFib is the most common type of abnormal heart rhythm (arrhythmia). About 2% to 9% of the population in the US have the condition. Could you tell AFib from a heart attack? Warning symptoms of atrial fibrillation are chest pain, shortness of breath, and nausea.

REFERENCE: CDC. "Atrial Fibrillation Fact Sheet." Updated: Aug 22, 2017.

Reviewed on 1/8/2019
Medically reviewed by Robert J. Bryg; Board Certification in Cardiovascular Disease/Internal Medicine


American Heart Association. "Prevention Strategies for Atrial Fibrillation (AFib or AF)." Updated: Oct 13, 2016.

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