Overview: Atrial fibrillation (afib, AF) is an arrhythmia in which one or both of the upper chambers of the heart (atria) beat chaotically.
The irregular activity of the atria is not immediately life-threatening, but it does have two consequences. Because the atria are not beating effectively, blood tends to pool in them and clots can form. People in afib have a 3-to-5-fold increase in their risk of stroke. Secondly, the ventricles - the lower chambers of the heart - are not getting a "kick" from the atria. Thus they do not beat as effectively as they would otherwise. Atrial fibrillation can be debilitating in the short term, and it poses a risk of stroke in the longer term. It is a serious problem!
HCM and afib
About 25% of patients with HCM will experience atrial fibrillation at some point. In patients who are obstructed, afib can be very debilitating.
Atrial fibrillation is not a "second disease." HCM tends to lead to atrial fibrillation for many patients. Over a long period of time, the increased pressures in the heart tend to lead to greater size of the left atrium The abnormal cellular structure of the HCM heart may also make HCM patients prone to afib.
A normal left atrial measurement in an adult is under 4.0 cm. Many with HCM have measurements in the 4.0-4.8 cm range. Those with left atria greater than 4.8 cm have a higher risk of developing atrial fibrillation.
Aside from the fact that you may feel debilitated by afib, you need to take it seriously and treat it quickly: afib tends to lead to more afib. The more episodes you have, and the longer they are, the more likely you are to have afib in the future.
What does atrial fibrillation feel like?
Unfortunately, it is not possible to be certain that you are in afib just from the way it feels. Some people do not even notice the arrhythmia - they are diagnosed when a doctor happens to use an ECG machine.(add in wearable - apple watch, etc) Other people feel strong palpitations and considerable weakness, as well as symptoms like shortness of breath. Unfortunately, the way you feel does not predict your risk: a person who notices no symptoms may develop a stroke! This said, many people do notice palpitations and feel weak and short of breath. If this happens to you, try to get a recording of your ECG using a home monitor, and send it to your cardiologist! Talk with your cardiologist about wearing an event monitor to try to capture an accurate record of an afib episode.
Treatment of afib
Doctors try medical management of afib first. There two sorts of approaches:
They try to control your heart rate, which can control most of the symptoms of afib
They can try to control your heart rhythm. Rate control usually involves drugs like beta blockers and calcium channel blockers. For many patients, this treatment is adequate.
Antiarrhythmic drugs can also be used. Because most of these drugs can also help cause arrhythmias, they are usually used after a strategy of pure rate control has failed. These drugs include betapace (Sotalol), tikosyn (Dofetilide), disopyramide (NorpaceCR), amiodarone (Cordarone), and dronedarone (Multaq). There are no large studies to tell us that any one of these drugs is necessarily the best. It is often necessary to try a few options to find which works best for you.
If medications do not manage your atrial fibrillation, there are additional steps that may help. An episode of afib can often be treated with electrical cardioversion. In this procedure, your heart is given a shock (while you are sedated) to restore a normal beat. Electrical cardioversion often works, but it is not usually permanent. It may be used to reset your heart, after which you need medications to maintain the new, regular heartbeat.
Another option for restoring sinus rhythm is a procedure called catheter ablation. This involves burning or freezing a small amount of tissue in your heart. A scar forms on the spot and prevents the abnormal electrical signals that cause atrial fibrillation. The scar can take a couple of months to develop and to stop the signals. Therefore, if you have the procedure done, it can take several months for it to "work."
In many HCM patients, this procedure may need to be repeated occasionally over one's life. While not a "cure" of atrial fibrillation, it can offer relief for weeks, months or years from atrial fibrillation.
An invasive treatment, called the maze procedure, may be used, usually when a myectomy or another open heart procedure is being performed. The maze procedure involves making incisions in the heart that restrict the abnormal electrical impulses to a certain area. It prevents the impulses from getting to the atria and causing the fibrillation.
Finally, some people with permanent afib may have a procedure called an AV node ablation. The AV node regulates the transmission of electrical signals from the atria to the ventricles. Ablating it means that the fibrillating signals from the atria are no longer transmitted to the ventricles. But it also makes it necessary to have permanent 100% pacing of the heart. It is not a "cure" of the abnormal rhythm; it is simply a "work around" that permits the heart to have a normal beat in the presence of atrial fibrillation. This procedure is NOT recommended for most, but may be an option for some.
Patients having afib run a risk of stroke. This makes it crucial to have anticoagulation therapy, using one of the available anticoagulant drugs. There are several of these drugs and it is not yet clear whether one is generally preferable to the others. Unfortunately, even if you have not had an episode of afib for some time, the probability of stroke does not appear to decline. It is recommended that you continue on anticoagulant drugs even if you have not noticed any episodes of stroke recently.
American College of Cardiology/European Society of Cardiology clinical expert consensus document on hypertrophic cardiomyopathy. A report of the American College of Cardiology Foundation Task Force on Clinical Expert Consensus Documents and the European Society of Cardiology Committee for Practice Guidelines.Maron BJ, McKenna WJ, Danielson GK, Kappenberger LJ, Kuhn HJ, Seidman CE, Shah PM, Spencer WH 3rd, Spirito P, Ten Cate FJ, Wigle ED; Task Force on Clinical Expert Consensus Documents. American College of Cardiology; Committee for Practice Guidelines. European Society of Cardiology.J Am Coll Cardiol. 2003 Nov 5;42(9):1687-713
Hypertrophic Cardiomyopathy for Patients, Their Families and Interested Physicians Second Edition: Maron and Salberg, Wiley publishing 2006
Effectiveness of atrial fibrillation surgery in patients with hypertrophic cardiomyopathy.Chen MS, McCarthy PM, Lever HM, Smedira NG, Lytle BL.Am J Cardiol. 2004 Feb 1;93(3):373-5
Five-year experience with the maze procedure for atrial fibrillation.Cox JL, Boineau JP, Schuessler RB, Kater KM, Lappas DG. Ann Thorac Surg. 1993 Oct;56(4):814-823
Substrate and procedural predictors of outcomes after catheter ablation for atrial fibrillation in patients with hypertrophic cardiomyopathy.Bunch TJ, Munger TM, Friedman PA, Asirvatham SJ, Brady PA, Cha YM, Rea RF, Shen WK, Powell BD, Ommen SR, Monahan KH, Haroldson JM, Packer DL.J Cardiovasc Electrophysiol. 2008 Oct;19(10):1009-14
Usefulness and safety of transcatheter ablation of atrial fibrillation in patients with hypertrophic cardiomyopathy.Gaita F, Di Donna P, Olivotto I, Scaglione M, Ferrero I, Montefusco A, Caponi D, Conte MR, Nistri S, Cecchi F. Am J Cardiol. 2007 Jun 1;99(11):1575-81
Efficacy of catheter ablation of atrial fibrillation in patients with hypertrophic obstructive cardiomyopathy.Kilicaslan F, Verma A, Saad E, Themistoclakis S, Bonso A, Raviele A, Bozbas H, Andrews MW, Beheiry S, Hao S, Cummings JE, Marrouche NF, Lakkireddy D, Wazni O, Yamaji H, Saenz LC, Saliba W, Schweikert RA, Natale A.Heart Rhythm. 2006 Mar;3(3):275-80
- G. A. Fox, 1/28/2021