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Atrial Fibrillation

Literature in HCM indicates that an estimated 25% of those with HCM will experience atrial fibrillation at some point. Atrial fibrillation is the presence of an abnormal heart rhythm in the top chambers of the heart - the atria.  In those with HCM with obstruction, or HOCM the presents of atrial fibrillation can be very debilitating.   It is important to remember that atrial fibrillation is not a "second" disease", it is a symptom of the underlying HCM, and may well be due to the increased pressures in the heart over a long period of time as well as the abnormal cellular structure of the HCM heart. The goal for some management of this heart rhythm disorder is rate control, which can be achieved with medication in many. For others more aggressive methods may be used to try to stop the abnormal rhythm.    

In HCM those with larger left atrial measurements may have more problems related to atrial fibrillation, although those with mildly dilated left atrial may also experience it.   A normal left atrial measurement in an adult is under 4.0, many with HCM have measurements in the 4.0 to 4.8 range.  Those with measurements of greater than 4.8 have a higher rate of atrial fibrillation based on data collected by the HCMA. 

There are two types of atrial fibrillation - paroxysmal and chronic - also known as "it comes and goes" and "it is always present".  Atrial fibrillation is a leading cause of stroke and therefore is important to identify and treat.  

First line treatments for atrial fibrillation is medication - beta blockers and antiarrythmics such as betapace (Sotolol), disopyrimide (NorpaceCR), or amioderone (Cordorone) are the most common and tried.  There are other medications such as Dronedarone (Multaq) and Dofetilide (Tikosyn) which have been used in HCM atrial fibrillation, but there are no large studies to indicate which works the "best" therefore it is often necessary to try a few options to find which works best in you. 

While attempting to manage the atrial fibrillation in HCM anticoagulation is critical.   There has never been a clinical trial to determine which is best in HCM and there remains concern and debate in this area.   The most common and long standing medication is Warfrin (Coumadin), which does require close blood monitoring with testing frequently.  There are several new anticougulants on the market including dabigatran (Predaxa), apiaban (Eliquis) and rivaroxaban (Xarelto).  There may also, based on the situation, be a need for Enoxaparin (Lovenox) or Heprarin.

If you have experienced atrial fibrillation and it has been well managed for a year with no further episodes, you can discuss with your HCM specialist removing the anticoagulant.

If medications do not manage your atrial fibrillation there are additional steps that may help.   The published data on atrial fibrillation often speaks about success rates over all, and it should be stated that those with HCM do not achieve the best outcomes and it is often necessary to repeat procedures. 

Sometimes medications cannot restore sinus rhythm, or they produce too many side effects. In this case, you may have an electrical cardioversion, which involves giving your heart a shock to set it and 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, when medications fail, 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".  Often times in HCM this procedure may need to be repeated over one’s life.  It is estimated to have a 40% success rate in HCM each time done.   While not a "cure" of atrial fibrillation, it can offer a relief for weeks, months or years from atrial fibrillation.    

An invasive treatment, called the Maze procedure, may be used, normally at the time of myectomy, when medications and other procedures have failed. It is open heart surgery, so the Maze procedure is more likely to be used if you have another heart condition requiring surgery. The 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. 

The last line of attack of atrial fibrillation is the rarely used option of ablation of the AV-Node (the natural pacemaker in the heart) and the use of dual chamber pacing to provide the atrial beat between atrial fibrillation.   It is not a "cure" of the abnormal rhythm it is simply a "work around" and permits the heart to have a normal beat in the presents of atrial fibrillation.   It is NOT recommended for most, but may be an option for some. 

** For children (<18) with atrial fibrillation and HCM it is advised to be evaluated by a high volume center as this is a very abnormal event and it could be an indication that there is a more complex disease present. 


Citations:
 

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

Atrial Fibrillation occurs in up to 25% of those with HCM.  There are many treatments available for atrial fibrillation.  To detect if you have atrial fibriallation your doctor may use a Holtor or event monitor, you can also purchase an AliveCor Monitor to attach to your smart phone to monitor yourself and share the results with your physician.