Brian Olshansky, MD, Professor of Internal Medicine
University of Iowa Hospitals and Clinics

Creation Date: May 2001
Last Revision Date: May 2001
Peer Review Status: Internally Peer Reviewed

What causes atrial fibrillation?

Atrial fibrillation is associated with many cardiac conditions, including cardiomyopathy, coronary artery disease, valvular heart disease, ventricular hypertrophy and other associated conditions. Atrial fibrillation has been associated with hyperthyroidism, acute alcohol intoxication, changes in the autonomic nervous system and is common after cardiac surgery. The most common condition associated with atrial fibrillation is high blood pressure. Some people have atrial fibrillation with no obvious source or associated condition. This is more frequent in younger people and it is called "lone" atrial fibrillation. It is likely that people who have this form of atrial fibrillation have had some inflammatory process or trauma to the atrium. Some people have a focal source that originates from the pulmonary veins.

Is atrial fibrillation associated with a heart attack or a stroke?

Atrial fibrillation is a very rapid irregular rhythm in the top two chambers of the heart. If one were to look at the heart as it were fibrillating, it would look like a bowl of Jell-O quivering. A heart attack is when an artery supplying blood to the heart blocks off causing damage to the heart muscle. A stroke occurs when an area of the brain does not get enough blood supply, in some cases due to a blocked artery supplying blood to the brain. This leads to brain damage and neurologic dysfunction. Atrial fibrillation can be associated with a heart attack or a stroke. Atrial fibrillation is a common cause of stroke in the elderly and up to 30 percent of the strokes in individuals over the age of 75 are due to atrial fibrillation. The reason that atrial fibrillation can be associated with, or cause, a stroke is because blood clots tend to form in the upper chambers, so-called atria, of the heart and these blood clots can break off and travel throughout the body, plugging up blood vessels. 25% of the blood goes to the brain in most cases, it is common that a blood clot, if it travels, will travel to the brain. It can also travel to the heart and clog up a vessel creating a heart attack or it can travel to any other area of the body causing a blocking in an artery--to the leg, for example, in the eye or any other organ. The risk of blood clots caused by atrial fibrillation increases in the following conditions: 1. hypertension, 2. heart failure, 3. diabetes, 4. increasing age.

Can a person be cured of this? Can it go away?

Yes. One form of atrial fibrillation that is treatable is so-called paroxysmal atrial fibrillation. This form of atrial fibrillation is more common in younger people and in people without serious underlying structural heart disease. In fact, this form of atrial fibrillation often occurs without any other underlying heart disease present. This paroxysmal form occurs when episodes of atrial fibrillation come for a short period of time and go away suddenly, to return later. This form is often associated with frequent extra beats in the atrium. In the electrophysiology laboratory, much the same kind of a place as a cardiac catheterization laboratory, catheters with electrodes on the tips can be placed into the heart to "map" the initiation of atrial fibrillation. The technology in this regard is advancing rapidly. Much of this form of atrial fibrillation originates from the pulmonary veins so the procedure is quite involved. It requires "transeptal puncture" to get the catheters to the left side of the heart. When the source is identified, an application of radiofrequency energy, or more recently, ultrasonic energy, is delivered to eliminate the spot creating the problem. For this form of atrial fibrillation, the success rate has been reported to be as high as 80 percent.

There are several important concerns using this number as a benchmark: 1. the procedure is really still new and somewhat experimental. 2. Not all electrophysiologists and not all centers have the expertise to perform this. 3. The long-term success rate is not clear because the follow-up has been in terms of months rather than years. 4. There may be multiple spots that trigger atrial fibrillation and they might not all be obvious at the time of the evaluation. 5. There are some potential risks of this procedure: one risk includes so-called pulmonary vein stenosis.

If multiple applications of energy are delivered into the site that triggers atrial fibrillation and if these sites are from the pulmonary vein, then it is possible to cause blockage of the pulmonary vein and this is a very dangerous situation. I would not want to dissuade you from therapy since this therapy can be curative, but there are significant risks such that it would make sense to consider other therapies first to keep the rates low or to supress episodes of atrial fibrillation. Atrial fibrillation also can be cured by a surgical procedure known as a MAZE procedure. Percutaneous approaches in the electrophysiology laboratory have been tried to recreate this MAZE procedure to cure atrial fibrillation in people who have it more chronically, or persistently, than a person who has paroxysmal atrial fibrillation. Atrial fibrillation can also go away on its own in some people. It tends to do this when there is a specific trigger such as coronary artery bypass surgery, hyperthyroidism, pericarditis, alcohol intoxication (or other stimulants such as some of the over-the-counter supplements, and even caffeine), other acute illnesses that cause extreme vomiting, and some conditions that lead to overexertion.

Is it safe to work out with this condition?

In general, it is not a good idea to workout too vigorously with atrial fibrillation unless you have been carefully evaluated for underlying heart conditions by a doctor. Some people who have atrial fibrillation have significant problems with their heart and with exercise, the heart rate can race tremendously during atrial fibrillation, thereby exacerbating the underlying heart condition and may lead to problems such as very low blood pressure, heart failure or a loss of consciousness. If the problem of atrial fibrillation has been well managed so that the rate is under control, or the rhythm is under control, it is possible to go back to standard physical activity in many cases. In fact, there are several professional athletes, including basketball players, who have atrial fibrillation present at times.

Is there a common drug therapy?

There are several approaches to atrial fibrillation management with drugs: 1. Drugs to control the heart rate during atrial fibrillation. 2. Drugs to keep someone in sinus rhythm. 3. Drugs to prevent blood clots that can happen from atrial fibrillation.

Let's consider the first category of drugs: Drugs to control heart rate include medications known as beta-blockers, calcium channel blockers and digoxin. Sometimes these drugs are given intravenously, but they are also available orally and these drugs are used to prevent the heart rate from speeding up too much during atrial fibrillation with exercise and they need to be adjusted so the rate does not get too slow at rest.

The second class of drugs to maintain normal rhythm include so-called antiarrhythmic drugs. Some of these drugs need to be started in the hospital. Some of the older drugs include Quinidine, Procainamide, Disopyramide, Flecainide, Propafenone, Sotalol, Amiodarone and a new drug known as Dofetilide. These drugs are not all approved by the FDA but all have been used for atrial fibrillation by doctors. Each one has its own set of side effects and benefits. Amiodarone is the most potent, but it has a large number of long-term side effects possible. Flecainide and Propafenone are not to be given to anyone who has an underlying heart condition.

The third types of drugs are blood thinners to prevent stroke and blood clots. These medications include Heparin and Warfarin. With this large compendium of medications, a doctor may select several, depending on the severity of the symptoms, the age of the patient, the presence of underlying heart conditions and response to other medications, the severity of the episodes and other risk factors for stroke.

I read the venom of the tarantula spider is being used to develop a drug to treat this condition, is there anything to it?

Yes, there is something to the use of tarantula spider venum. No drug has yet been developed but a report in the journal Nature on January 4, volume 409, page 35, describes the response of atrial fibrillation to this toxin. It works in a different way than the other medications so far developed and it works on stretch channels in the heart. If this proves to be effective, it may provide insight into causes of atrial fibrillation and the development of potentially new useful therapies.

Is it true that some people have no symptoms until they have a stroke?

Yes, it is true. For some people, atrial fibrillation represents no more than a new, annoying palpitation. For other people, it can be the cause for a stroke but the process might have been unrecognized until that point. The older you are, and the more risk factors you have for stroke, as I mentioned earlier, the greater the chance that without being on a blood thinner, that atrial fibrillation will cause a stroke. With several risk factors present, an older person can have a risk factor for stroke as high as 17 percent each year. One issue about atrial fibrillation is that there are those that have it and do not even recognize that it is present. Stroke can be caused by atrial fibrillation even in younger individuals and it is one of the potential causes for stroke in which no obvious cause can be diagnosed.

Is Digitalis still used to treat irregular heartbeat? It's been around forever!

Digitalis is one of the treatments used for patients with atrial fibrillation. It comes from the foxglove plant. Digitalis is used mainly to control the rate of the heart during atrial fibrillation. It is not our best drug to control the rate but may be more useful in elderly, less active patients and in patients who cannot take a beta-blocker or a calcium channel blocker. It may also be useful in patients who have atrial fibrillation and congestive heart failure. Digitalis at high doses can be potentially toxic and in anyone who has kidney problems, or is taking Quinidine, or Verapamil (a calcium channel blocker), the levels of Digitalis can increase substantially.

Can over-the-counter drugs cause irregular heartbeats? Do symptoms go away when the use of the OTC is discontinued? Or can you cause permanent damage?

Regarding the first question, yes, some over-the-counter drugs can cause irregular heartbeat and some OTC drugs can be associated with atrial fibrillation. The ones of concern are the ones that include adrenalin analogs. Adrenalin is made in the body and it increases the heart rate and blood pressure. Pseudoephedrine is one such compound. This is present in many cold and decongestant preparations. It is important to recognize that some weight loss products and some over-the-counter herbal compounds contain an herb known as ma huang. This herb has ephedrine in it. It is important to look at the ingredients in some of these weight loss products or OTC herbal products because this herb can cause irregular heart rhythm and has been associated, in some instances, with sudden death due to cardiac arrest. If an irregular rhythm, or atrial fibrillation, is triggered by an OTC preparation, it may persist for some period of time. But generally, it goes away on its own. However, once atrial fibrillation starts, and if it is not corrected by intervention and does not go away on its own, over time, the presence of atrial fibrillation in which the rate of the heart is not kept under control means there can be permanent damage to the heart.

Are women more likely than men to have an irregular heartbeat or vice versa?

Actually, with atrial fibrillation, it's men who have more disease. However, women are more likely to feel their irregular heart rhythm and to have irregular heart beats. Younger people with atrial fibrillation tend to be men and tend to be highly symptomatic with their episodes of atrial fibrillation. Younger women tend to feel extra beats both in the upper and lower chambers of the heart. Older women tend to be more likely, than men, to have atrial fibrillation where it is reversed at a younger age.

Are there any underlying conditions that make a person more prone to an irregular heartbeat?

Yes. While an irregular heart beat can occur independent of any other heart condition, it is worth having the problem checked out because an irregular heart rhythm may be a sign of a concerning underlying heart condition such as cardiomyopathy, heart failure, coronary artery disease, valvular heart disease and other conditions like that.

Do things like caffeine or intensive exercise enhance a heart arrhythmia?

Caffeine and intense exercise are some of the triggers for irregular heart beats and in particular, atrial fibrillation. It is important to try to relate any irregular heart beat and the presence of atrial fibrillation to what is going on at the time. Because some people will go to a doctor and mention that they drink, for example, a large amount of caffeinated beverages, and have atrial fibrillation. The doctor may restrict them unnecessarily from drinking caffeinated beverages, and there may be no benefit in doing so. On the other hand, if the individual recognizes a relationship between drinking caffeinated beverages and irregular heart rhythms, then it would make perfect sense to abstain from this. Similarly, with exercise and alcohol ingestion.

Is tachycardia the same thing?

Atrial fibrillation is a form of tachycardia. Tachycardia really means a fast heart rhythm. There are many forms of tachycardia. Most people think of tachycardia as a supraventricular tachycardia. But, there are many other forms of tachycardia. Supraventricular tachycardia is a specific rapid rhythm often due to a spot in the top chamber of the heart that is beating rapidly, or it is due to an abnormal electrical pathway that allows for a kind of "short circuiting" of the heart. These pathways can be eliminated by ablation techniques in the electrophysiology laboratory. Tachycardia can be a normal response to exercise, this is known as sinus tachycardia. The heart rate will race simply because of the exercise. Another form of tachycardia, a potentially life-threatening form, is known as ventricular tachycardia. It is when the lower chambers of the heart are racing rapidly.

If you are diagnosed and treated for atrial fibrillation, and experience fast heart rhythm, could you take additional meds?

Yes, you can take additional medication but is very important to realize that the medicines that are available for atrial fibrillation can interact with each other in a bad way. One reason to take additional medicines would be to try to stop the rhythm. Fleconaide and Propafenone, two antiarrhythmic medications are sometimes prescribed to be taken only when the rhythm occurs. This would be safe as long as these medications are indicated for that specific individual (they would not be for an underlying heart condition) and you should never mix two antiarrhythmic medications. Sometimes medications, which are given, are given specifically to keep the heart rate under control. If the heart rate gets faster, it would be appropriate to take a little extra of these medications. It is unlikely that taking a blood thinner, specifically at the time of the onset of atrial fibrillation, would be of any use.

What we have discussed today is the problem of a serious condition known as atrial fibrillation. This common medical problem has many different presentations and associations with other conditions. There are new advances in therapies, some of which can cure atrial fibrillation, which are being investigated further. Medical therapy often requires multiple adjustments until the proper prescription is achieved for any given individual. Any therapy that is used for atrial fibrillation has potential risks and must be prescribed on an individualized basis. A "one-size-fits-all" for atrial fibrillation simply does not work. Newer therapies are being developed at a rapid rate and it is likely that in the next five to ten years, cures for atrial fibrillation will be common and perhaps of lower risk than they are now.