Atrial fibrillation is the most common abnormal heart rhythm. It can result in the heart beating too slow, too fast, or in a rhythm that leads to sensations of chest pain, breathlessness, dizziness, skipped heartbeats, or sudden loss of consciousness.
Education about the causes, symptoms, and treatment of atrial fibrillation is very important as it can lead to sudden drops in blood pressure, heart failure, and stroke if untreated.
Atrial fibrillation can be caused by a myriad of conditions. The most common conditions leading to atrial fibrillation include:
- Heart attack
- Pulmonary embolism (blood clot in the vessels of the lung)
- Hyperthyroidism (overactive thyroid gland)
- Drug or alcohol use – cocaine, amphetamines
- Electrolytes abnormalities
- Excessive caffeine intake
- Certain medications
The atria are the upper two chambers of the heart and have a large number of electrical pathways passing through them. Any of these conditions can lead to damage of these pathways or change the flow of electrical signals. This change in the way electricity flows through the heart leads to an abnormal heart rhythm and the symptoms of atrial fibrillation.
This condition may also occur in individuals that have a family history of atrial fibrillation. Genetics are thought to play a role in how different people react to the conditions listed above and who develops atrial fibrillation.
Approximately 2.2 million individuals in the United States are affected by atrial fibrillation. This makes it the most common abnormal heart rhythm in the country and one of the most common cardiac conditions.
Atrial fibrillation is most common in elderly men, those with other heart diseases, and hospital patients. Conditions that increase the risk of heart disease such as diabetes, high blood pressure, and high cholesterol also increase the risk of atrial fibrillation. However, anyone of any age can have atrial fibrillation including young and otherwise healthy individuals.
Atrial fibrillation alone has very few signs and symptoms that you would recognize at home. A sensation of skipped heartbeats and palpitations (a noticeably irregular or strong heartbeat) are often the only symptoms.
When atrial fibrillation results in an excessively fast heart rate, over 100 beats per minute, is known as atrial fibrillation with rapid ventricular response (Afib with RVR), it results in far more severe symptoms than atrial fibrillation with a normal heart rate.
The most common symptoms of severe afib, such as Afib with RVR include:
- Shortness of breath
- Chest pain
- Loss of consciousness
These symptoms occur because the abnormal electrical signals in the heart that lead to atrial fibrillation can sometimes stimulate an extremely rapid beating of the heart that the body cannot support safely for a long period of time. This leads to insufficient oxygen reaching the heart muscle, causing chest pain and shortness of breath. The rapid beats are also less effective at moving blood and can lead to reduced blood flow to the brain which may lead to loss of consciousness.
The complications of untreated atrial fibrillation are far more concerning than its symptoms. If the heart is allowed to beat too fast for too long it can lead to permanent damage to the heart, which will cause heart failure. The abnormal beating of the heart can also lead to blood clots forming within the heart. These blood clots can break off and lead to a stroke if they become lodged in the blood vessels of the brain.
Atrial fibrillation is diagnosed based on symptoms, physical examination, and electrocardiogram (ECG). ECG is very valuable in this setting because it shows the electrical activity of your heart and can determine whether your symptoms are caused by atrial fibrillation or another abnormal heart rhythm. It also helps rule out one of the most worrisome causes of new atrial fibrillation – heart attack.
Your doctor will also likely order a chest x-ray to get a picture of your heart size and evaluate for structural abnormalities in the lungs. They will also usually obtain an echocardiogram – an ultrasound of the heart – to evaluate your heart’s structure and function.
Lastly, your doctor will typically get blood tests to check your electrolytes, thyroid function, and heart muscle enzymes to look for metabolic causes of atrial fibrillation and to evaluate for cardiac injury such as heart attack. Occasionally, a urine drug screen will be ordered as well.
If your doctor suspects that you have a pulmonary embolism, they might order a test called a CT angiogram – this evaluates for blood clots in the blood vessels of the lung.
The acute treatment of atrial fibrillation depends on whether or not it is an emergency. If your heart rate is significantly elevated, your blood pressure is very low, and you are not getting adequate blood supply to your brain, they may cardiovert or “shock” your heart back to a normal rhythm. This is done in an emergency room under moderate anesthesia and is considered very safe when done by a skilled physician.
If none of these emergency situations exist but your heart rate is still significantly elevated, they will likely administer an intravenous medication to slow down your heart rate. These medications may include:
- Beta blockers
- Lopressor ( metoprolol)
- Calcium channel blockers
- Cardizem ( diltiazem)
- Lanoxin (digoxin)
Eventually, your doctor will likely transition these intravenous medications to an oral formulation that will be taken multiple times a day.
Depending on your risk factors for blood clots and if your heart rhythm returns to normal following medication or cardioversion (e.g. history of heart failure, hypertension, advanced age, diabetes, stroke), your doctor may also start you on an oral blood thinner medication such as Coumadin (warfarin) to decrease your risk of stroke.
Warfarin interacts with a host of medications and foods (e.g. spinach). This medication also needs to be monitored very closely with regular blood tests – therefore, most patients are started on newer oral anticoagulants such as:
- Xarelto (rivaroxaban)
- Eliquis (apixaban)
- Pradaxa (dabigatran)
Occasionally, your cardiologist may attempt to bring your heart back to a normal rhythm instead of simply reducing your heart rate. Before attempting this, they may have to perform a transesophageal echocardiogram to check if the abnormal heart rhythm from atrial fibrillation has resulted in a blood clot forming within the heart. This procedure is performed under mild sedation, and a camera is directed down your esophagus to get a better view of the chambers of the heart that these blood clots typically form in. This is important because returning the heart to a normal rhythm while a blood clot is present can lead to that blood clot leaving the heart and causing a stroke.
If there is no blood clot, they may cardiovert your heart as mentioned above, then start an antiarrhythmic medication to prevent the atrial fibrillation from returning (e.g. Cordarone (amiodarone), Multaq (dronedarone), Tambocor (flecainide)). If there is a blood clot, they will place you on one of the anticoagulants listed above for several weeks to help dissolve the clot before attempting cardioversion.
Cases that are refractory to medical therapy may require the use of interventional procedures such as cardiac ablation. During this procedure, your cardiologist will access your heart through an artery in the groin or arm. They will then attempt to cauterize the area of your heart that is responsible for the electrical currents leading to atrial fibrillation.
- January CT, Wann LS, Alpert JS, et al. 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on practice guidelines and the Heart Rhythm Society. Circulation. 2014 Dec 2;130(23):2071-104. – https://www.ncbi.nlm.nih.gov/pubmed/24682348
- Xu J, Luc JG, Phan K. Atrial fibrillation: review of current treatment strategies. J Thorac Dis. 2016 Sep;8(9):E886-E900. – https://www.ncbi.nlm.nih.gov/pubmed/27747025
- Copley DJ, Hill KM. Atrial Fibrillation: A Review of Treatments and Current Guidelines. AACN Adv Crit Care.2016 Feb;27(1):120-8. – https://www.ncbi.nlm.nih.gov/pubmed/26909462