How medical imaging helps cardiologists treat hypertrophic cardiomyopathy

While echo is mandated for the use of mavecamten, cardiac MRI and CT also play a role in assessing HCM patients.

“Cardiac MRI is key in the evaluation of these patients. Ten or 20 years ago, it was not as frequently used as it is now. MRI can help establish the diagnosis when echocardiography is sometimes borderline. And before you speak to a patient and give them this diagnosis, you want to be comfortable and the MRI can confirm that,” Nagueh explained. 

He said MRI can identify pathology in patients with an established diagnosis that echo might not be able to detect. This includes apical aneurysms. MRI also can quantify the scar burden injected HCM, which can help assess the risk of heart failure later on as the patient’s disease progresses. The scar burden also can play a roll in determining if the patient should have a defibrillator implanted.   

Why are serial echocardiograms needed in mavecamten patients? 

Echo is used in serial exams of mavecamten patients to ensure they are getting the correct dose of the drug, Nagueh said. The impact of the drug is assessed through serial measurements of HCM hypertrophy. The dose can be raised or lowered according to imaging findings. 

The echo results are also used to assess ejection fraction. If a patient gets too much of the drug, Nagueh said their ejection fraction can drop and they may go into heart failure. 

When therapy is initiated, echo exams are performed every month for the first three months. Once a patient is stable on a given dose, echos are performed every three months. If the dose changes, Nagueh said echo exams are scheduled in closer intervals. He said assessing the LVEF with actual measurements is necessary to be more accurate in HCM to catch any changes. He also warns visual assessments of ejection fraction should not be used. 

“For physicians who rely on visual assessment, in my experience it is not the best approach because you are looking for trends over time,” Nagueh said. 

Nagueh said Houston Methodist performs full echo serial exams on HCM patients, which also includes the use of strain imaging. But he noted that the bare minimum assessment needed is for the patient’s LVOT gradient and ejection fraction.