be informed about... Atrial Fibrillation Information for patients Atrial fibrillation (AF) is an abnormal heart rhythm. This pamphlet answers some questions you may have about AF, and gives an overview of the structure and function of the heart. From the Atrial Fibrillation Clinic and The Harvard Thorndike Electrophysiology Service of the CardioVascular Institute at Beth Israel Deaconess Medical Center
How your heart works: an overview The heart is a muscle. Its job is to pump blood to the rest of the body. It has four chambers or sections. The two top chambers are called atria (each one is an atrium), and the two bottom chambers are called ventricles. What causes the heart to pump? In the normal heart, a small area in the right atrium called the sinoatrial or sinus node (SA node) sends an electrical impulse (a small burst of electricity) across the heart muscle. This impulse is sent 50-90 times a minute, and it causes the heart muscle to contract in an orderly way first the atria, then the ventricles. This orderly beating of the heart is called normal sinus rhythm. In a person who is in normal sinus rhythm, you can tell how often the SA node is sending these impulses by counting the pulse. As the atria contract, they squeeze the blood into the ventricles. The right ventricle pumps the blood to the lungs, where it is filled with oxygen. The blood returns to the heart and the left ventricle pumps it to the rest of the body. As the blood flows to the rest of the body, it also flows to the heart muscle itself through blood vessels called the coronary arteries. This gives the heart the energy it needs to keep pumping. What is atrial fibrillation? Atrial fi brillation (AF) is an abnormal heart rhythm (an arrhythmia). In normal sinus rhythm, the sinus node sends electrical impulses through the heart muscle in a regular way. In atrial fibrillation, many small electrical impulses are formed in the atrium which collide and compete with one another. With so many small signals being sent out at once, the atria don t contract in the usual coordinated way. Instead, they quiver or fibrillate, thus the term atrial fibrillation. Without a strong coordinated contraction, the atria don t empty as well as they should with each heart beat. Some of the blood that normally gets pumped into the ventricles remains in the atria instead. This stationary blood (blood that is not moving) can form clots (clumps of blood) in the atria, particularly in one area called the left atrial appendage. If these small clots get pumped to the body, this is an embolism which can possibly result in a stroke. Please see below for ways to prevent a stroke caused by atrial fibrillation. Normal electrical pathways Sinus (SA) node Antrioventricular (AV) node Normal sinus rythm Normal Heart In addition to affecting the electrical impulses in the atrium, atrial fibrillation has an effect on the ventricle. The small, rapid signals from the quivering atria move to the ventricle, causing it to beat in a rapid, irregular way. This irregular pulse can be felt in a person with atrial fibrillation and explains the palpitations (the pounding heart feeling) that many persons in atrial fibrillation experience. Atrial fibrillation is an abnormal heart rhythm which may come and go in some patients. In this case it is called paroxysmal atrial fi brillation. In other patients, atrial fibrillation is present all the time and is called chronic atrial fi brillation. What is atrial flutter and how does it differ from atrial fibrillation? Atrial fl utter is another arrhythmia, or abnormal heart rhythm, which often develops in the right atrium. Atrial flutter often occurs along with atrial fibrillation and can be considered a cousin of AF. Treatment of atrial fibrillation and atrial flutter are similar, except when it comes to an ablation (cauterization or burning) procedure. (See page 7 for more about ablation as a treatment option.) 2
Abnormal electrical pathways Heart in Atrial Fibrilliation How common is atrial fibrillation? Atrial fibrillation is the most common abnormal heart rhythm. It is present in 15% of people over age 75, but it can be seen in young people as well. Over 2 million Americans that are admitted to hospitals in the United States have AF. Many more have the condition, but are not admitted to hospitals. We expect that as the American population continues to age, we will see more and more cases of AF. What are the dangers of having atrial fibrillation? Atrial fi brillation Why does atrial fibrillation occur? We don t fully understand what causes atrial fibrillation. What we do know is that certain conditions make it more likely that someone will develop AF. These risk factors for AF are listed in the box below. However, it is important to realize that 30% of patients with AF have no known risk factors at all. Risk factors for AF High blood pressure (hypertension) Disease of heart valves (e.g. rheumatic heart disease) Age greater than 50 years Congestive heart failure Coronary artery disease Cardiac surgery Structural problems in the heart Heavy use of alcohol, or binge drinking Hyperthyroidism Pericardial inflammation (pericarditis) Sleep apnea The most serious danger of having atrial fibrillation is the risk of having a stroke. As mentioned above, in atrial fibrillation the atria don t contract normally and the stationary blood can form clots. If a blood clot develops in the heart and is then pumped out of the heart, it can travel to the brain and cause a stroke. We know that the risk of developing a clot and potentially a stroke is not the same for every patient. The risk factors that clearly increase a patient's chances of developing a stroke are listed below. Risk factors for stroke in AF Age greater than 65 years High blood pressure Rheumatic heart disease Diabetes Congestive heart failure History of stroke or transient ischemic attack (TIA) Vascular disease (problems with the blood vessels) Being female A second danger with atrial fibrillation has to do with the ventricles beating too fast. This rapid and irregular heart beat can cause patients to feel palpitations, shortness of breath, dizziness, or fatigue. In rare cases, months and months of a rapid heart beat can lead to weakening of the heart muscle. It can result in fluid build-up in the lungs and shortness of breath. This is called congestive heart failure. 3
Can atrial fibrillation cause a heart attack or cardiac arrest? A heart attack occurs when the arteries to the heart (coronary arteries) become blocked and a portion of the heart muscle no longer receives oxygen and other important nutrients. When this happens, an area of the heart muscle dies; this is what we call a heart attack. The most common symptom of heart attack is chest pain or pressure. Atrial fibrillation is an abnormality of the heart s electrical impulses, not an abnormality of the blood supply to the heart. Therefore, atrial fibrillation does not cause heart attacks. It is important to note that some patients with atrial fibrillation also have blocked arteries, so-called coronary artery disease. In these patients, the fast heart beat caused by atrial fibrillation can lead to chest pain because of the inefficient way the heart pumps blood. That is, because of the rapid heart beat, the amount of blood flowing through the coronary arteries may be reduced. If there is already a blockage in the arteries, this further reduction in the blood flow may cause discomfort. Talk to your doctor or nurse practitioner about what to do if you have chest pain. Remember, anyone with new chest pain should call 911 right away. Cardiac arrest is a term used when the heart suddenly stops pumping blood. This is usually caused by abnormal heart rhythms that come from the bottom chambers of the heart, the ventricles. The irregular rhythm of AF comes from the atria (the top chambers) and does not cause cardiac arrest. In other words, atrial fibrillation is not a life-threatening condition. Will I have atrial fibrillation forever? What is my prognosis? Some people have paroxysmal atrial fibrillation; in other words, the AF comes and goes. Patients with this type of AF usually have it off and on for many years. AF that does not go away on its own is called chronic atrial fibrillation. Chronic atrial fibrillation is more common in older patients and is generally a lifelong problem. It may or may not go away with treatment, but it usually comes back over time. It is unusual for AF to go away forever or be cured completely. Once present, AF usually comes back. It can return hours after cardioversion (see below) or not for many years. Even though there is no cure, most people with AF can live a full, active life with careful attention to controlling the heart rate, preventing stroke, and (when possible), reestablishing normal rhythm. How is atrial fibrillation treated? Treatment of atrial fibrillation is not the same for everyone. The particular treatment that we use will depend on each individual case. Sometimes, a choice can be made and patients are asked what they prefer. So it s important that you understand treatment options and ask your doctor or nurse practitioner about anything that isn t clear. AF treatment falls into two broad categories: preventing complications of AF (preventing stroke and controlling heart rate) and, in some cases, restoring or maintaining normal sinus rhythm. Preventing complications Your doctor or nurse practitioner will talk to you about: reducing the risk of stroke decreasing symptoms caused by a high, irregular heart rate Preventing stroke The majority of patients with atrial fibrillation are at risk of having a stroke. Patients with AF who have one or more of the risk factors mentioned above should take an anticoagulant (blood thinning) medicine. One commonly prescribed anticoagulant is warfarin (Coumadin). Warfarin thins the blood to a different level in different people, and its effectiveness can be influenced by foods or other medications. In order to determine if the dose of warfarin is right, anyone taking it must have a blood test (called an INR) regularly about once a week at the start of therapy, then every two to four weeks for as long as the medicine is taken. A major side effect of warfarin is bleeding. For most people, this is a minor annoyance. (For 4
example, it takes longer for bleeding to stop after a minor cut.) In rare cases, patients on warfarin can have serious bleeding problems, such as bleeding from a stomach ulcer. This usually happens when the blood has become too thin. That is why the frequent blood tests are so important. Several other options for blood thinners are available and may be prescribed, depending on your needs. These do not require blood tests and do not interact with food or other medications. Dabigatran (Pradaxa) and Apixaban (Eliquis) are taken twice a day. There are different doses available that your doctor or nurse practitioner may prescribe, depending on your age and kidney function. Rivaroxaban (Xarelto) is taken once a day with a meal of at least 500 calories, and may also be used in a lower dose, depending on your kidney function. Patients with paroxysmal atrial fibrillation may still need blood thinners even when their atrial fibrillation has gone away. This is because the AF could come back and cause a stroke. The decision about whether to take anticoagulants even after atrial fibrillation has stopped is made by weighing the risk of stroke against the risk of bleeding. It is a decision the doctor or nurse practitioner will discuss with each patient individually. Controlling heart rate Atrial fibrillation is not a life-threatening arrhythmia. Many patients are in atrial fibrillation for years and live active, productive lives. For patients with chronic atrial fibrillation, it is important to control the heart rate and prevent it from becoming too rapid. If the heart rate remains rapid for months, it can possibly weaken the heart muscle and cause congestive heart failure. A number of medicines are useful to control heart rate in a person with AF. The main types are beta blockers (e.g. metoprolol, atenolol, propranolol, nadolol), and calcium channel blockers (e.g. diltiazem, verapamil). Sometimes, digoxin is also given to control the heart rate. Some patients with AF develop problems if the heart rate becomes too low, due to medicine or other factors. Doctors sometimes use a pacemaker to make sure the heart rate doesn't get too low. The pacemaker does not cure the AF. Restoring and/or maintaining normal sinus rhythm Stopping atrial fibrillation and restoring normal sinus rhythm is called a cardioversion. In patients with paroxysmal atrial fibrillation, cardioversion can happen on its own when the heart s electrical system returns to normal suddenly. In other words, the AF goes away with no treatment. If this is going to happen, it usually happens in the first 48 hours after the AF began. In some patients, atrial fibrillation does not go away on its own. When this happens, we can sometimes cause a cardioversion using an electric shock (electrical cardioversion) or medicine (antiarrhythmics). Electrical cardioversion is successful in about 85-95% of cases, medicine in about 30%. In some patients, we may also recommend an interventional procedure (either a catheterbased ablation or a MiniMaze procedure) to significantly reduce the frequency of AF. Electrical cardioversion Electrical cardioversion is a routine and safe procedure. Prior to cardioversion, the patient is given a small amount of anesthesia through an intravenous line (IV). This anesthesia puts the patient to sleep so the shock is not felt. The cardioversion is then done by placing pads on the patient s chest and delivering a small amount of electricity. The electrical current stops the AF and restores the heart to a normal rhythm in most patients. At the CardioVascular Institute, this procedure is performed every day and on an outpatient basis (the patient does not have to stay overnight in the hospital). Although it is very rare, the main risk from an electrical cardioversion is stroke. A stroke can occur at the time of the cardioversion, or in the days or weeks to follow. Studies have shown that for patients who have been in atrial fibrillation for less than 48 hours, the risk of stroke is almost zero. The risk of stroke is also very, very low if the person has been fully treated with anticoagulants, or if a transesophageal echocardiogram (described in the box on the next page) showed no clot in the heart. Other possible complications from cardioversion include: slight burn to the skin of the chest or back, which is similar 5
to a sunburn and will fade over time; a more dangerous fast heart rhythm, which can be immediately treated wth another electric shock; or, in patients with heart failure, an increase in heart failure symptoms for a few days following the procedure. Medicines used to prevent AF Quinidine Procainamide Disopyramide Transesophagael echocardiogram (TEE) A transesophageal echocardiogram (TEE) is a procedure that allows your doctor to look for blood clots inside the heart to evaluate your risk for stroke. It is usually done before an electrical cardioversion. If there is no evidence of clot in the heart, it is generally safe to have a cardioversion. Before the TEE procedure, you will be given a sedative medicine to relax. We then pass a special tube through the mouth and down the throat to the esophagus. Because the heart sits in front of the esophagus, the TEE instrument can get detailed pictures of the heart to look for clots. The TEE is 99% effective in finding these clots. The main risk of the TEE is a sore throat. A rare complication is a tear in the esophagus, but this generally happens in people who already had problems related to the throat or esophagus. If you have any difficulty swallowing, or if you know of any problems with your esophagus, please tell your doctor or nurse practitioner before the procedure. Antiarrhythmic medication If you have had a successful cardioversion and the AF has stopped, or if your AF comes and goes (paroxysmal atrial fibrillation), we can give you medicine to try to prevent atrial fibrillation from coming back. Medicines that prevent atrial fibrillation are called antiarrhythmic medicines and are listed in the box on this page. On average, antiarrhythmic medicines successfully prevent atrial fibrillation in 50-70% of patients. Unfortunately, these medicines work differently in different patients, and there is no Flecainide (Tambocor) Propafenone (Rythmol) Sotalol (Betapace) Dofetilide (Tikosyn) Amiodarone (Cordarone) Dronedarone (Multaq) way to predict which medicine will prevent atrial fibrillation in a particular patient. For this reason, we may need to try several medicines before finding the right one. Some antiarrhythmic medicines cannot safely be given to patients with coronary artery disease or kidney problems. If you have either of these, please tell your doctor or nurse practitioner. Antiarrhythmic medicines have side effects. Some of these side effects can be serious. In some cases, patients must be admitted to a hospital when starting these medicines. Other medicines require outpatient heart monitoring, stress tests, chest x-ray, or blood work once or on a periodic basis. It is important to follow all of the instructions you get from your doctor or nurse practitioner about any monitoring you may need. Interventional procedures For some patients, doctors will recommend a procedure to try and prevent the AF from coming back. We have learned that the abnormal electrical impulses seen in atrial fibrillation often start in the veins that drain into the heart. These veins (pulmonary veins) drain blood from the lungs into the left atrium. The abnormal electrical impulses from these pulmonary veins travel to the left atrium and then to the right atrium causing atrial fibrillation. Recently, procedures have been developed to prevent the electrical impulses from traveling from the pulmonary veins into the left atrium. We 6
believe that by cutting off the electrical activity between the pulmonary veins and the heart, we can reduce the amount of AF that occurs and in some cases even cure it. There are two procedures currently available that cut the electrical circuitry from the pulmonary veins to the left atrium. The first is a catheter-based procedure called pulmonary vein isolation. The second is a surgical procedure called a Maze procedure. There are two types of Maze procedures. One is a minimally invasive procedure called MiniMaze and the other is a full operative procedure that is performed when the patient requires open heart surgery for another reason. In general, for patients whose primary cardiac problem is atrial fibrillation and for whom a surgical approach for ablation is felt to be best, if they do not need heart valve or bypass surgery, we recommend a MiniMaze procedure. Catheter-based pulmonary vein isolation procedure Description: The catheter-based procedure is called a pulmonary vein isolation procedure. Multiple long wires, called catheters, are placed through the veins in the groin. These catheters are advanced into the heart to the region where the pulmonary veins drain into the left atrium. The area is then ablated or cauterized (burned) using radio waves. Cauterization destroys the tissue around the pulmonary veins so that electrical activity is prevented from entering the heart, helping to prevent the start of atrial fibrillation. This procedure is usually done under general anesthesia. Effectiveness: This procedure is about 70% effective at lowering the frequency of atrial fibrillation episodes. It also lowers the symptoms associated with atrial fibrillation. In some cases the AF may be completely cured. Approximately 30% of patients will have a recurrence of AF after the procedure. If this happens in the first few months after the procedure, it may quiet down with time. Ocassionally, the doctor may recommend a repeat procedure to touch up areas that may have re-grown electrical connections. Risks include: Damage to the heart muscle causing blood to leak out of the heart. This occasionally requires drainage of the blood around the heart and, very rarely, surgery A 1% risk of stroke due to clot formation on a catheter inside the heart Formation of a connection between the heart and esophagus (very, very rare) Injury to the blood vessels in the groin which may require surgery Significant bleeding into the groin or abdomen requiring transfusion Length of procedure and recovery: The catheterbased procedure generally takes between three and six hours. Patients stay in the hospital overnight so that we can monitor the heart rhythm and any potential complications. After the procedure, patients should not do any heavy lifting or exercise for one week. Patients whose job does not include heavy physical labor can usually return to work two or three days after the procedure. Minimally invasive surgical Maze procedure MiniMaze Description: The MiniMaze procedure is an operation, done by a cardiothoracic (heart) surgeon. This procedure attempts to electrically isolate the pulmonary veins from the left atrium. The procedure involves two small (three-inch) incisions (cuts) on both sides of the chest, under the arms and between the ribs. The surgeon uses a small fiberoptic camera to find the area where the pulmonary veins drain into the left atrium. This area is then cauterized (burned). An electrophysiologist (cardiologist specializing in problems with the heart's rhythm) usually assists the surgeon to ensure that electrical isolation is complete. At the end of the procedure, the surgeon removes the left atrial appendage, a small sack-like structure on the left atrium where most clots form in atrial fibrillation. Doctors believe that removing the left atrial appendage lowers the risk of stroke; however, this has not yet been proven in a scientific study. Effectiveness: MiniMaze is about 70% effective at lowering the frequency of atrial fibrillation episodes. It also lowers the symptoms associated with atrial fibrillation. In some cases the AF may be completely 7
cured. Approximately 30% of patients will have a recurrence of AF after the procedure. If this occurs in the first few months after surgery, it may quiet down with time. Risks: The major risks include bleeding, infection, and, rarely, death. Length of procedure and recovery: The operation lasts between three and six hours. Most patients stay in the hospital for approximately three days after surgery. It usually takes about three or four weeks until the chest feels back to normal. What are the main differences between the catheterbased approach and the MiniMaze approach? The catheter approach is not a surgical procedure (operation). It is done through small holes in the veins in the groin which do not leave scars. The recovery from this procedure is one night in the hospital and a week without heavy lifting or exercise. During the catheter-based procedure, small clots can form on the catheters and potentially result in a stroke. In contrast, the MiniMaze is an operation with incisions in the chest. The recovery from this procedure is longer, often several days in the hospital and then several weeks until patients are back to their usual activities. However, because the operation is done from the outside of the heart, the risk of stroke is very, very small. Also, because the left atrial appendage is removed during this procedure, patients may be at lower risk of a stroke in the future. What should I do if my atrial fibrillation comes back? If you develop an episode of atrial fibrillation and have severe chest pain or pressure, new shortness of breath, or passing out, you should call 911. If you have milder symptoms such as palpitations or you simply notice an irregular or rapid pulse, you do not need immediate medical attention. Instead, tell your doctor or nurse practitioner during working hours that you are having a recurrence and await further instructions. In fact, 50% of patients with paroxysmal atrial fibrillation will go back to sinus rhythm without medical intervention within two to three days of a recurrence. For more information We hope this information has been helpful. For more information on your health condition or for a consultation with one of our arrhythmia specialists, please call (617) 667-8800 and ask for an appointment with an arrhythmia specialist. Notes 8 LC1686 Rev. 05/14