ASA or myectomy?
For most people with HCM, medication is enough to treat their condition. However, those with severe obstruction and many symptoms may benefit from ASA or myectomy. While ASA seems appealing because it is less invasive, myectomy has a stronger record of both safety and success. Myectomy is not recommended for patients who are poor risks for surgery. Generally this means people who are very frail because of age or other medical conditions. In those people, an ASA may be able to reduce their obstruction and relieve many of their symptoms. Because ASA requires very particular heart anatomy, it cannot be done in everyone. If you also need mitral valve repair, coronary artery bypass, or repositioning of the papillary muscles, they cannot be done during an ASA.
Some interventional cardiologists think of ASA as a first line of intervention because it is easier to perform and less invasive than myectomy. The idea that some suggest is to have an ASA first, and later have a myectomy if the ASA does not provide enough relief from symptoms. This is a bad idea! ASA normally leaves patients with Right Bundle Branch Block (RBBB), while myectomy normally leaves them with Left Bundle Branch Block (LBBB). These mean that normal electrical signals to the right (or left) ventricle are blocked. If you have RBBB the right ventricle still gets an electrical signal, because the signal to the left ventricle travels around and stimulates the right ventricle after the left ventricle. But if you have both an ASA and a myectomy both signals will be blocked and you will need a pacemaker 100% of the time. People do live with complete heart block, but this is not a sensible strategy for treating HCM!
Finding a center
ASA is more successful and safer when it is performed at a center where the doctors have considerable experience with HCM (Ommen et al. 2020). Having a multidisciplinary team of other doctors who treat HCM, like electrophysiologists and imaging specialists, also makes a big difference. In other words, the best results are at recognized Centers of Excellence for HCM.
Preparing for the procedure
You may need to stop taking certain medications, like beta blockers, before the procedure. You should also not eat or drink anything after midnight the day before your procedure. You may also need to have a chest x-ray, blood tests, an echocardiogram, and an electrocardiogram so the doctor performing the procedure is fully informed about how your heart performs. Normally you will have had a cardiac catheterization before the ASA, so the doctor can assess whether you are a good candidate for the procedure.
The procedure
The ASA may take 1-2 hours. You will be awake, but may be given medicine to help you relax. You may also be given aspirin and heparin (a blood thinner) to make blood clots less likely. A local anesthetic will be applied to the skin in your groin, and a small incision will be made. Your doctor will insert a small catheter into an artery or vein which will then be threaded to your heart. Angiography and echocardiography may be used to ensure that the catheter is placed correctly. A small amount of pure alcohol will be released through the catheter to an artery in your septum. This may feel uncomfortable. Measurements of the pressure in your heart will be taken before and after the procedure to make sure that it has improved. After the procedure, the catheter will be removed and the insertion site will be bandaged.
After the procedure, you will be taken to a recovery room where your vital signs will be monitored. Your doctor may also order an echocardiogram after the procedure to see how successful it was. You will need to lie flat and not bend your legs for several hours after the procedure to prevent bleeding. You may be prescribed anticoagulants (blood thinners) and pain medication. You will most likely stay in ICU observation for 1-3 days. If you have a heart block, you may need to have a permanent pacemaker.
Your doctor will talk to you about guidelines for medication, recovery, and returning to normal activities. Your symptoms may continue for a while after the procedure, even though most people do say their symptoms improve immediately. After you leave the hospital, it is important to follow the instructions given to you by your doctor.
Risks
ASA is generally safe. There are risks, as with any surgery. These risks partly depend on your medical history. Risks may include abnormal heart rhythm, bleeding at the incision site, infection, blood clots, tears in the heart tissue, abnormal fluid buildup around the heart, and shock. RBBB is expected. Occasionally ASA results in complete heart block, making the patient 100% pacemaker dependent. The tissue death caused by ASA results in some scarring in your heart. This can make arrhythmias more likely. Your doctor will discuss the risks and benefits of ASA with you before the procedure.
