When the hypertrophy of the septal wall begins to block the left ventricular outflow tract (LVOT), a surgeon can go through the aortic valve to remove sections of the septal tissue causing problems. This requires advanced CT or MRI imaging to show details of the anatomy and septal thickness to plan where and how much tissue to remove. From this, Smedira said, the surgeon can create a 3D image in his mind of the anatomy and know where and how much to cut.

The procedure is partly guided by transesophageal echo (TEE), because the surgeon has a limited surgical view of the septum and ventricle looking through the aortic valve. He said TEE is also used to take additional measurements during and after the procedure.

Some centers are now using 3D-printed models as a new technology to better plan and guide these procedures. Cleveland Clinic uses 3D printed models created from a CT scan of the patient's heart, which is used in the operating room as a reference. But even with advanced imaging and 3D models, these procedures can still be challenging and takes a higher volume of procedures for surgeons to become proficient. 

"There is no doubt there is a learning curve. It is challenging because there is no margin for a mistake when you only have something that is 15 or 16 millimeters thick. So education training and sessions like we had here are important when building multidisciplinary teams," Smedira explained. 

He said proctoring other surgeons how to perform the procedure is essential. But, even some high volume HCM centers might still have relatively low numbers of these surgeries, because HCM is a rare cardiac disease. At Cleveland Clinic, Smedira helps proctor other cardiac surgeons so they perform these procedures.

There are now 50 HCMA Centers of Excellence in the United States. They work like a hub-and-spoke model, where hospitals in their region refer HCM patients to the center of excellence, which see higher volumes of HCM patients and build expertise in surgery and the alternative therapy of catheter-based alcohol septal ablation. HCM also has different presentations, so if there is mitral valve involvement, he said these centers of excellence will have structural heart experts they can include on the treatment team.

"This model gives patients the opportunity to go where they will get the best outcome if they have things that make their care more challenging," Smedira said. 

Raising the bar on HCM care and myectomy procedures

With the introduction of mavacamten, Smedira said the HCM landscape has changed very rapidly. Patients can now try the medication to see if it can control the hypertrophy and prevent the need surgery or alcohol ablation. The drug has also led to cardiology paying much more attention to HCM, and many centers are now trying to learn more about how to diagnose and treat these patients. Some patients will still require the more invasive procedures, so a key topic to explore is how to best manage HCM patients and when to be more aggressive with interventions. 

However, today there are no clear standards on how to image HCM, what findings to report, where to take measurements in the anatomy or how to best care for these patients. The HCM Forum event was a planning meeting for top HCM experts to outline these issues so they can be addressed in an organized fashion with new evidence-based guidelines and creation of best practice protocols. 

"The great thing is that now there is this critical mass of content experts that are coming together in this multidisciplinary forum. We are really working to refine and understand how to best serve the patients from start to finish across these multiple imaging modalities and disciplines. We really need to start to standardize how we do things and then we can study it and find out what works well and what doesn't work," Smedira said.