In particular, two types of exercise testing are most valuable for HCM patients:
- Exercise Echocardiogram: These tests are valuable in determining whether a patient has obstruction. It provides a physiological way to measure whether or not a patient has an obstructed left ventricular outflow tract and hence, may potentially be in need of an invasive procedure to treat the obstruction. According to the article, approximately 1/3 of HCM patients have latent obstruction which may only be seen during or after exercise. This obstruction is not always apparent from their resting echocardiogram.
- Cardiopulmonary Exercise Testing: These tests help determine functional capacity and provide a quantifiable indicator of heart failure symptoms. This test can identify patients in need of more aggressive treatment options, or who are potentially in need of transplant. A particularly valuable piece of data from this test is the “VO2 max” score, which is a measure of the maximum rate of oxygen consumption during exercise which reflects the cardiorespiratory fitness level of a person.
*Editor’s note – Exercise testing was particularly informative and important in my own HCM treatment. It was only after my doctors performed an exercise echo that the extent of my obstruction became apparent. The symptoms I had been suffering appeared to be out of proportion to what was visualized on my resting echo. The exercise echo helped my doctors understand the cause of my symptoms which made the next step, in my case a myectomy, much clearer.
You can read my full story here .
Alcohol septal ablations (ASA) have been available to HCM patients as a treatment option for the last 20 years. While the procedure has been the subject of great controversy, some physicians have recently advocated for expanded indications of the ASA procedure.
An editorial in this week’s Journal of the American College of Cardiology from the Netherlands argues that the safety of ASA has been firmly established because mortality rates from ASA have been shown to be comparable to those from septal myectomy. The Dutch doctors maintain that past concern about ventricular arrhythmia resulting from the scar left by the ablation have not born out.
Making ASA Safer
Now, they argue, the focus should shift from justifying the procedure toward perfecting the procedure. In particular, the need for additional or repeat procedures must be reduced. Additional procedures have been necessary due to incomplete resolution of obstruction and/or the need for pacemaker implantation due to heart block, neither of which are a common consequence following myectomy. 1 in 10 patients require a pacemaker following ASA, while only 1 in 25 require one following a myectomy. 1 in 13 patients require a subsequent intervention after ASA (either another ASA or a myectomy), which is 15 times the rate of re-intervention after a myectomy.
The researchers’ suggestions for improvement include: 1) performing ASA only in hypertrophic cardiomyopathy centers of excellence that perform high volumes of the procedure; 2) improving patient selection through the use of a multi-disciplinary team which includes a cardiologist specializing in imaging, a cardiac surgeon, and an interventional cardiologist; 3) using 3D myocardial contrast echocardiography in order to select the best vessels; and 4) use of a small targeted amount of alcohol.
Impact of 3D Myocardial Contrast Echocardiography
In particular, the researchers explain that 3 dimensional myocardial contrast echocardiography (MCE) has proven to be a helpful tool in selection of the appropriate septal perforator. The use of MCE has resulted in a change in strategy in 15% to 20% of cases: either by a change in which blood vessel is selected for the alcohol or by prompting the immediate discontinuation of a procedure if the MCE shows that other parts of the heart could be affected. MCE has also improved the success rate of ASA, while allowing for a more compact scar.
Counterpoint Editorial Advocates National Registry to Quantify Results
An accompanying editorial by Dr. Paul Sorajja from Minneapolis Heart Institute argues that we do not have the data necessary to reconcile the differences in outcome between myectomy and ASA. In order to better understand the long-term potential and risks of ASA, mandatory reporting should be required. He points out that this is what is done in other multidisciplinary transcatheter-based therapies, e.g. transcatheter aortic valve replacement for the treatment of aortic stenosis and transcatheter repair of mitral regurgitation with MitraClip. These procedures require: 1) the use of multidisciplinary teams; 2) participation in a national registry (i.e., The Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy Registry); and 3) comprehensive reporting of procedural and 1-year outcomes.
Therefore, Dr. Sorajja proposes a national registry created that includes the following information:
- risk factors for sudden cardiac death
- LVOT gradients
- Standardized definitions for procedure success
MyoKardia’s experimental drug MYK-461, currently in Stage 2 trials for humans, has now been shown to eliminate left ventricular obstruction in five cats with HCM. It has already been shown to inhibit traits of HCM in mice.
Addressing these findings, Associate Professor Joshua Stern, chief of the Cardiology Service at the University of California, Davis, veterinary hospital, stated:
Based on these positive results, U.C.Davis is hoping to conduct a clinical trial of MYK-461 to determine whether it could become the standard of care for cats with HCM.
I have had the joy of being a Registered Nurse for over 40 years. I was born wanting to be a nurse and started bandaging teddy bears at the age of three. By the age of 5, I was creating “medicines” by spinning blades of grass mixed with clover flowers in the front wheel well of an upside down tricycle.
As I got older, I moved on to be a Candy Striper and a Nurse’s Aide, and then I went on to get my degree as a RN, a BSN, and MSN and became a teacher, administrator, and researcher. All of this cannot REALLY prepare you for; “Being on the other side of the bed” which is what happens when a health care professional who is used to caring for patients becomes a patient themselves. Continue reading “Guest Blogger – Surgical Myectomy: A Twice in a Lifetime Experience – By Jill Celeste”