Atrial Fibrillation: Basic Information

Background

Atrial fibrillation is the most common cardiac arrhythmia, affecting over 5.1 million people in the United States alone.   Each year there are over 340,000 new cases in the US.   By the year 2050, the number will be 12-16 million.   Instead of the atrium (the smaller, top chamber of the heart) beating from a single source of stimulation, it beats in a disorganized way which may impair the ability of the chamber to fill the larger chamber known as the ventricle.  This disorganized electrical activity causes irregular heart beats that lead to blood pooling and clotting, which can cause stroke and other serious health issues.   People who suffer from atrial fibrillation may have palpitations (pounding, fluttering, “flip-flop”, or racing feeling in the chest), lack of energy, dizziness, chest discomfort, and difficulty breathing during normal activities or even at rest. 

 

What Causes Atrial Fibrillation?

For about 50% of patients with atrial fibrillation, there is no discernible trigger or cause.   About 40% of cases occur in the post-operative setting with open heart surgery or other surgery that involves general anesthesia.  

 

Risk factors:

High blood pressure

Diabetes

Coronary artery disease

Smoking

High or low levels of electrolytes such as potassium, magnesium, and calcium

Obesity

Sleep apnea:  Obstructive sleep apnea or central sleep apnea

Thyroid dysfunction:  in particular hyperthyroidism

Aging:  Prevalence roughly doubles with each decade of life

Heavy alcohol consumption (also known as “holiday heart”)

Hereditary:  The condition can run in families

Lung disease:  ie: COPD/emphysema, lung fibrosis

Infection:  In particular lung infection such as pneumonia/bronchitis

Other:  emotional stress/anxiety, trauma, illicit drug use

 

Diagnosis

Sadly, many patient’s first knowledge of their having atrial fibrillation is at the time of a stroke or as part of the later workup for “cryptogenic stroke” (a stroke with know known cause).  It can be an elusive condition as some patients may have long periods of time in normal rhythm with shorter periods of time in atrial fibrillation.  While some patients are symptomatic and feel/know when they are in atrial fibrillation, many do not.  If a physician suspects that you may have this condition, or if you have the symptoms mentioned above, an electrocardiogram (ECG) or a Holter (24-hour ECG) can assist in making the diagnosis.   If it is not observed on the 24-hour ECG, then you may be asked to wear a 30 day monitor.  If, however, the patient does not show atrial fibrillation on the 30 day monitor and the suspicion is high for arrhythmia, an implantable monitor known as a loop record can be inserted under the skin in the chest.  This is a very small monitor (roughly the size of a AAA battery) that can call in to a central monitoring service.  Insurance generally dictates the order of testing.

 

In addition, it is important to modify any and all potential known risk factors as listed above.  In some cases, simply correcting these risk factors may relieve the patient of atrial fibrillation.  Additionally, screening for other risk factors is important (such as blood work, sleep study, etc).

 

Treatment of atrial fibrillation

The treatment of atrial fibrillation is a step-wise process which generally starts with medications and then progresses to more invasive treatment options as outlined below.

 

Medication

Medications (drug therapies) for A-Fib patients are designed to address three main categories: heart rate, heart rhythm, and stroke prevention.   Your treatment team will discuss a “rate control” strategy vs a “rhythm control” strategy to regain and maintain normal heart rhythm, control the heart rate (pulse), and prevent stroke.

 

            Medicines used to control heart rate

            Medications such as calcium channel blockers (diltiazem or verapamil) or beta blockers (metoprolol or carvedilol)  may be employed to better control the heart rate in atrial fibrillation.  These drugs can reduce blood pressure         some but that is not their main effect.  Since heart rate can be very difficult to control with atrial fibrillation, do not be surprised if your care team needs to increase the dosing of these medication or add additional medications to your regimen.

 

            Medicines to control heart rhythm

            The most common medications used to attempt to control rhythm include: Tambocor (flecainide), Multaq (dronedarone), and Cordarone (amiodarone).  The decision to use these medications depend on the patient, the presence of heart failure or coronary disease, and other considerations.  You may be asked to have a stress test to determine if that is the underlying cause of the A-fib but also to help determine which medications may be appropriate. 

 

            Medicines to prevent stroke

            Since stroke can be a catastrophic result of atrial fibrillation.  Your care team will use a validated scoring system to determine your risk of stroke with atrial fibrillation.  Depending on your risk profile, you may qualify for aspirin therapy alone or more complete anticoagulation with agents such as Coumadin (warfarin), Xarelto (rivaroxaban), Eliquis (apixaban), or Pradaxa (dabigatran).  A number of different considerations must me made in choosing if anticoagulation is the right thing to do (patients prone to falling/injury may be in a situation in which the risk of bleeding outweighs their risk of stroke).  Once that decision has been made, then your care team will discuss which agent may be best for you.

 

 

 

Cardioversion

Your care team may recommend a cardioversion to restore your heart to normal rhythm.  There are two types of cardioversion: chemical and electrical. Cardioversion through the use of drugs is called chemical cardioversion.  Electrical cardioversion uses a low-voltage, timed electrical shock to restore normal rhythm while the patient is sedated.

 

Most cardioversions are planned and scheduled several weeks in advance.  However, if your A-Fib is so irregular and rapid that it is life threatening, you may be sent to the emergency room, given an anticoagulant, and an electrical cardioversion performed.  Depending on the acuity and the timing, your care team may ask you to have a special type of echocardiogram performed to look to see if there is a blood clot in the heart prior to cardioversion.

 

              Chemical Cardioversion

              The goal of chemical cardioversion is to make your heart beat in normal rhythm). It is usually done in a hospital.  Some combination of medications is administered intravenously.  Chemical cardioversion is often done in combination with Electrical Cardioversion described below.

 

              Electrical Cardioversion

              During Electrical Cardioversion you are anesthetized and are unconscious when you receive the shock from the small electrical pads placed on the chest and the back.  The shock causes the signal producing areas of your heart to discharge all at once. This stops all electrical activity in your heart momentarily, hopefully allowing your normal heart rhythm to take over. Often times, only one shock is required to restore normal rhythm.

 

 

Catheter Ablation Procedure

If traditional techniques do not restore or keep you in normal rhythm, your care team may refer to an electrophysiology cardiologist.  This type of cardiology specialist may offer an ablation procedure which is a specialized catheterization procedure designed to locate the areas of the heart that produce the atrial fibrillation and isolate or treat them.  The success rate for ablation procedures continues to increase and generally has a success rate of 75-90%.

 

Summary

While atrial fibrillation can be frustrating for the patient as it can cause significant symptoms and usually requires multiple medications to control heart rate, rhythm and prevent stroke.  However, since it is the most common arrhythmia your care team is expert at working with you in this regard.

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