**Because so much HCM information was presented at the Summit, this is the third of multiple blog entries. Stay tuned to HCMBeat for more highlights from the HCM Summit. To see Part I of this series of highlights from the HCM Summit VI, click here and to see Part II of this series click here.**
The symposium was organized by long time HCM expert Dr. Barry Maron and his son, Dr. Martin Maron. Both Marons are now affiliated with Tufts Medical Center’s Hypertrophic Cardiomyopathy Center.
What follows are summaries from selected talks presented at the meeting. The presenter and their hospital affiliation are noted below, along with the topic of their presentation. When possible, you may access the presenters’ slides via hyperlink by clicking on the name. (Note that not all presenters made their slides available).
- Obstructive HCM – In 90% of HCM patients with functional disability, the cause is heart failure due to left ventricular outflow tract obstruction which is reversible via myectomy or alcohol septal ablation.
- Approximately 70% of HCM patients have obstruction. 37% have obstruction at rest while 33% have obstruction which is provocable and can only be seen through the use of exercise echocardiography testing.
- Non-Obstructive HCM – Most nonobstructive HCM patients have few symptoms and are at low risk of progressive heart failure. Transplant is a possibility for the small number of nonobstructive patients who go on to develop advanced heart failure.
*Editor’s Note: Dr. Bradley Maron is the son of Dr. Barry Maron and the brother of Dr. Martin Maron.
- Pulmonary hypertension is common in HCM patients with obstruction who are referred for septal reduction procedures but it does not usually need to be treated separately.
- Right heart catheterization is the only way to properly diagnose pulmonary hypertension in HCM. Echocardiogram is not adequate and may lead to misdiagnosis.
Dr. Joseph Dearani, Mayo Clinic, Rochester, MN – Septal Myectomy: Note that Dr. Dearani has additional slides you can find here.
- When obstruction has been removed, patients live normal life spans and have less discharges of their ICD.
- Mayo’s three myectomy surgeons (Dr. Joseph Dearani, Dr. Hartzell Schaff and Dr. Sameh Said) perform between 200 – 250 myectomies per year.
- Myectomy does not leave a septal scar in the heart unlike alcohol ablation which leaves scarring which will later be visible on MRI.
- Mayo Clinic has particular expertise in myectomy surgery treating mid-ventricular obstruction. In this surgery, the surgeon extends the myectomy to remove additional muscle further down into the ventricle via the standard approach through the aortic valve. If all of the obstruction cannot be removed this way, then the surgeon may use an additional trans-apical approach in order to access all of the obstructive tissue in the mid-cavity.
- It is unusual for obstruction to recur after a patient undergoes myectomy. A second myectomy is usually only necessary if the initial myectomy was incomplete.
- Myectomy does not lend itself to be performed minimally invasively or robotically at this time. The potential for incomplete myectomy and the inability to deal with complications is too great.
- Experience of the surgeon in performing myectomy is crucial.
- Long term mortality rates of ASA are similar to those from myectomy.
- Historically, a key difference between ASA and myectomy outcomes has been the need for pacemaker implantation following ASA. More recently this need has decreased due to the refinement of the ASA procedure and the use of less alcohol.
- Evaluation of patients suitable for ASA should be done by an interdisciplinary team considering all possibilities and any co-morbid conditions so that the most fitting procedure will be selected. Current guidelines recommend ASA only when myectomy is contraindicated or too risky. Only 65% of patients are candidates for ASA due to anatomical considerations.
ASA is less invasive than myectomy, requires less recovery time and is cheaper. However, it may also have to be done more than once.
- Mitra-Clip therapy could be a viable option for patients who are not good candidates for myectomy.
- Mitra-Clip Therapy in HCM creates a percutaneous plication of the mitral valve leaflets, thereby preventing systolic anterior motion of the mitral valve. It also broadens the left ventricular outflow tract, normalizing left ventricular pressures and relieving mitral regurgitation.
- Because Mitra-Clip is minimally invasive and does not create scar tissue, there is no need for a post-procedure pacemaker.
- Extent of improvement can be assessed during placement of the device. If the Mitra-Clip does not effectively improve blood flow, the procedure can be aborted, the device removed, and the patient can instead proceed to myectomy.
- The procedure is not dependent on the patient’s anatomy or the extent of hypertrophy.
- So far, the procedure has only been tried in a small number of patients. Results have been mixed. Further study will demonstrate its long term potential.