What is atrial fibrillation?
Atrial fibrillation is the most common sustained heart rhythm disorder. Normally the heartbeat originates in the sinus node and spreads in an organized fashion throughout top chambers (atria) of the heart. Each of these regular impulses is conducted to the bottom chambers of the heart (ventricles). In atrial fibrillation, the top of the heart has rapid and chaotic activity, resulting in a loss of the squeezing function within the atria and this can result in the formation of blood clots that are an important cause of stroke. Furthermore, the bottom of the heart tends to breat rapidly and irregularly, leading to symptoms of fatigue, weakness, shortness of breath and palpitations.
Who gets atrial fibrillation?
1-2% of the U.S. population (nearly 3 million people) live with atrial fibrillation and up to 20% will experience it during their lifetime. The incidence of atrial fibrillation rises sharply with increasing age. Often the exact cause of atrial fibrillation in any given patient is difficult to determine, but risk factors include hypertension, diabetes, obesity, alcohol use, as well as any "structural" abnormalities of the heart, such as valvular heart disease, coronary artery disease, prior myocardial infarction, or congestive heart failure. There are also some reversible causes of atrial fibrillation, such as thyroid abnormality, pneumonia, pulmonary embolism, recent heart surgery, and in these cases atrial fibrillation may resolve with treatment of the underlying cause.
How can atrial fibrillation be treated?
The first goal in treatment of atrial fibrillation is stroke prevention. For many patients, this means use of the blood thinner warfarin (Coumadin). Use of warfarin requires careful blood test monitoring, but will prevent the majority of strokes from atrial fibrillation. Taking blood thinners has risks, but multiple research studies show that the benefits of stroke prevention far outweigh these risks. At the Atrial Fibrillation Institute, we also have investigational blood thinners available as part of research trials that have some practical advantages over warfarin and we can assess your candidacy for these trials if you would like. There are other patients whose age, medical history and infrequency of atrial fibrillation episodes suggest low stroke risk and aspirin may be used. Finally, some patients may not be good warfarin candidates because they are at very high risk of serious bleeding, cannot get follow-up blood tests or are at high risk for falls. It is important to understand that aspirin provides much less stroke protection of warfarin, but is the next best alternative. Recent data has shown that clopidogrel (Plavix) is another blood thinner that can be added to aspirin for an intermediate level stroke risk reduction if warfarin cannot be taken.
The second goal of treatment involves alleviating the symptoms of atrial fibrillation. This can be done by allowing atrial fibrillation to persist, but controlling the heart rate. This strategy involves the use of beta-blockers, calcium channel blockers, and digoxin either alone or in combination. Rarely, implantation of a pacemaker with a relatively simple procedure called "AV junction ablation" is helpful, but results in the patient being "dependent" on a pacemaker for their basic heart rhythm.
The other key approach to controlling symptoms in atrial fibrillation is to maintain sinus rhythm. Some patients bounce in and out of atrial fibrillation on their own (called "paroxysmal" atrial fibrillation) while others will stay in "persistent" atrial fibrillation. In the case of persistent atrial fibrillation, a patient can be converted to sinus rhythm with a simple procedure called a cardioversion. This is usually done with a small shock that jolts the heart into normal rhythm while the patient is under anesthesia. Often this procedure may be combined with a trans-esophageal echo (TEE) when it is necessary to exclude the possibility of blood clots in the heart.
Whether you have paroxysmal or persistent atrial fibrillation, medications are often needed to keep the heart from going back out of rhythm. Medicines most frequently used for this purpose include propafenone (Rythmol), flecainide (Tambocor), sotalol (Betapace AF), dofetilide (Tikosyn), disopyramide (Norpace), dronedarone (Multaq), and amiodarone (Cordarone, Pacerone). Choosing between these agents is a complex decision that requires a high degree of individualization based upon age, underlying medical conditions, heart function, kidney function and side effect profile of each medicine.
What is catheter ablation of atrial fibrillation and when is it appropriate?
When at least one medication fails to control symptoms of atrial fibrillation, catheter ablation is advocated by the American Heart Association, American College of Cardiology and the Heart Rhythm Society for suitable patients. Because atrial fibrillation is a complex heart rhythm that can involve multiple regions of the heart, catheter ablation of atrial fibrillation is somewhat more complex than many other catheter ablation procedures.
While we didn't used to think of atrial fibrillation as a rhythm that could be approached with catheter ablation, cardiothoracic surgeons began to have success with the MAZE procedure, where the atria of the heart were divided into small compartments. The next major breakthrough came in the late 1990's, when it was discovered that sleeves of heart tissue that extend from the left atrium of the heart back into the pulmonary veins can fire rapidly and are the "triggers" for atrial fibrillation in 85-90% of new onset cases of atrial fibrillation. Initial approaches involved using a catheter to reach back into the pulmonary veins to ablate these areas directly. This worked sometimes, but problems with this method included (1) other areas in the culprit pulmonary vein or other pulmonary veins could begin to fire leading to a recurrence of atrial fibrillation and (2) ablating inside of the pulmonary veins can cause the vein to narrow, a problem termed "pulmonary vein stenosis."
Experience and collaboration among doctors from all over the world led to rapid advances in atrial fibrillation ablation. The most common procedure now involves encircling all 4 pulmonary veins to prevent the impulses that could initiate and perpetuate atrial fibrillation from ever getting out of the pulmonary veins and into the heart. In some patients, additional ablation may be required if triggers for atrial fibrillation involve regions outside of the pulmonary veins. If atrial fibrillation continues uninterrupted for a long period of time, it may promote many areas of the heart to perpetuate atrial fibrillation and it may become more difficult to ablate all of these areas.
What steps are involved in preparing for atrial fibrillation ablation?
Along with a careful medical history and physical examination, basic cardiac tests such as an ECG, echocardiogram, routine blood tests and either a stress test or cardiac catheterization are required in assessing candidacy for atrial fibrillation ablation.
Prior to the procedure, a CT scan will be performed to define the shape of your left atrium along with the number, size and location of your pulmonary veins. This image will also be used during your procedure.
Warfarin and antiarrhythmic medications will be stopped about 3 days prior to the procedure. If you are using amiodarone, you may be asked to stop it a few weeks sooner. In some cases, we will use "Lovenox" subcutaneous injections twice daily to keep the blood thin as warfarin is wearing off. On the morning of the procedure, it is important NOT to take any medications, especially NOT Lovenox to avoid the blood being too thin during the procedure.
Selected patients may require a trans-esophageal echocardiogram (TEE) prior to their ablation procedure.
What is the likelihood of success from atrial fibrillation ablation?
Single Procedure Success Rate Estimates
- 80-90% of patients are improved after a single procedure
- 60-70% No atrial fibrillation seen, off antiarrhythmic drugs
- >90% Atrial fibrillation symptoms markedly improved
Frequency much less or now easily controlled by drugs
* Some patients (persistent atrial fibrillation, more significant associated heart disease) have more difficult to treat variants of atrial fibrillation and we may have lower success rates.
Repeat Procedures: Can be considered if results of first procedure unsatisfactory and will improve the overall success rates. This may be required in up to 20% of patients to cure their atrial fibrillation.
Stopping Warfarin: Considered on case-by-case basis depending on patients risk of stroke.
What are the risks of atrial fibrillation ablation?
Overall approximate complication rate:
- 2% Major or serious complications.
- 3% Minor complications.
While catheter ablation is a low risk procedure, some of the possible complications can be serious. Certain of these complications are common to all catheter procedures, such as bleeding, injury to arteries or veins, cardiac perforation or tamponade (accumulation of blood in the sac around the heart). Additional risks associated with atrial fibrillation ablation include anesthesia risks, narrowing (stenosis) of pulmonary veins, strokes, heart attacks, injury to the esophagus. The possibility of death related to catheter ablation for atrial fibrillation is very low, but in large series of patients is probably on the order of approximately 1 in 1000 cases.
We take every precaution to avoid complications. These include:
- A highly experienced team of physicians, nurses and technicians
- A new, state-of-the art, $3 million laboratory designed for catheter ablation procedures
- Using a multiple plane X-ray machine to know our catheter's location in the heart
- Using advanced mapping systems utilizing 3D ultrasound to identify critical cardiac structures
- Thinning the blood during the procedure to prevent blood clots
- Minimizing ablation over the esophagus
- Measuring temperature inside of the esophagus to avoid heating it
- Monitoring the patient overnight after the procedure
Will I be able to stop medications after atrial fibrillation ablation?
Will I be able to stop medications after atrial fibrillation ablation?
Frequently, a successful atrial fibrillation ablation can lead to discontinuation of anti-arrhythmic medications. In some patients this can mean up to 3 or 4 medicines. However, if you need medications for other underlying heart disease or hypertension, these will still be required.
Some patients are understandably interested in stopping anticoagulation medications such as warfarin (Coumadin). If you have had a prior stroke or TIA, we may be reluctant to recommend discontinuation of warfarin. If there is no evidence of recurrent atrial fibrillation, we can have a discussion about the risks and benefits of using aspirin instead of warfarin.
Typically, aspirin can be considered a few months after ablation if a patient is considered low risk for stroke. If multiple stroke risk factors are present, atrial fibrillation ablation may be appropriate to control symptoms of atrial fibrillation, but not as a means of stopping warfarin. As always, the use or omission of warfarin involves an individualized estimation of the risks of stroke versus the risks of a bleeding complication.
What do I do on procedure day?
Report to the Heart and Vascular Unit of St. Vincent's Medical Center promptly at the time specified. You will meet with your electrophysiologist and your anesthesiologist. You will be brought into our procedure room and sedated. We typically put 2 little tubes in the both the right and left femoral veins (groin area).
During the procedure, we will look at the left atrial anatomy from the CT scan, including the size, shape and number of your pulmonary veins. One of our catheter has a "GPS sensor" in the tip of it, so we can see where it is in your heart just like a satellite can find where your car is on the map. Using this advanced technology, we can create a 3-dimensional reconstruction of your heart and see where our catheter is at any point in time. Finally, we typically "merge" your CT scan with our catheter derived reconstruction of your heart and perform ablation within your heart's own reconstruction.
Once we have ablated all the areas that we deem necessary, we will remove our catheters, remove the IV tubes from your legs and wake you up from anesthesia. You will be monitored until you are stable and then transferred to a cardiac floor where we will monitor you overnight. About 80% of our patients are ready for discharge on the day following the procedure.
What is the required follow-up after atrial fibrillation ablation?
In the first couple of weeks after the ablation procedure, you must notify our office (904-388-1820) immediately if you experience fever, severe chills, weakness in an arm or leg, difficulty speaking or any signs of bleeding from the groin site, mouth or in the stool. In addition, over the first 3-6 months, call if you experience progressive shortness of breath or a new recurrence of palpitations.
Typical follow-up after atrial fibrillation ablation includes a visit within a month and at 3, 6, 12, 18 and 24 months post-procedurally. We will perform periodic Holter monitors or other telephone-based monitoring of your heart rhythm. If atrial fibrillation recurs, we may consider a repeat procedure or re-institution of anti-arrhythmic medications as appropriate.
What are the alternatives to undergoing atrial fibrillation ablation?
For a select group of patients, surgical MAZE procedure can be appropriate, particularly if other indications for heart surgery exist.
Who is a good candidate for atrial fibrillation ablation?
All patients considering atrial fibrillation ablation should have symptoms and/or impaired quality of life from their atrial fibrillation. The most ideal candidates for atrial fibrillation ablation have paroxysmal atrial fibrillation (starts and stops on its own) and have either failed or developed side-effects in response to at least one anti-arrhythmic medication. Even if atrial fibrillation is persistent rather than paroxysmal, it is encouraging if the patient is able to maintain some period of sinus rhythm after cardioversion with antiarrhythmic medications.
The left and right atria should not be too large and the patient should not have too severe structural heart disease (such as thickening of the heart, weakening of the heart, advanced congestive heart failure, severe valvular disease).
Finally, all patients must accept peri-procedural warfarin anticoagulation for at least one month before and 2-3 months after their procedure and they must understand and accept the risks and benefits of the procedure.
What are our goals for catheter ablation of atrial fibrillation?
Our only concern is the safety and welfare of our patients. We are excited about the prospect of eliminating atrial fibrillation. We will pursue catheter ablation in patients who we feel have a reasonable probability of success, acceptable level of risk, good understanding of these risks and benefits, and good intentions of complying with pre-procedure testing and follow-up.