AuthorisedTherapeutic exploratory (Phase II)Interventional

Learning From Early Aficamten In HCM (LEAF-HCM)

Hypertrophic cardiomyopathy (HCM) is an inherited condition that causes the walls of the heart muscle to become unusually thick and stiff. This can make it difficult for the heart to pump blood out to the rest of the body, often leading to tiredness, chest discomfort, or breathlessness. The LEAF-HCM study is exploring whether a new tablet called aficamten (also known as MYQORZO) can help. Aficamten works by gently relaxing the heart muscle so it does not contract too forcefully. In this Phase II trial, adult participants will take either aficamten or a dummy tablet (placebo) for 54 weeks. Doctors will track changes in blood flow, heart muscle thickness, and overall heart function using heart scans, blood tests, and physical checks. The main goal is to see if treating HCM early can improve blood flow and protect long-term heart health.

At a glance

Status

Authorised

Phase

Therapeutic exploratory (Phase II)

Sponsor

Erasmus Universitair Medisch Centrum Rotterdam (Erasmus MC)

Enrolment target

Start

21 Sep 2026

Hypertrophic cardiomyopathy

What is this study about?

Hypertrophic cardiomyopathy (HCM) is a long-term heart condition where sections of the heart muscle wall become thicker than normal. When the muscle thickens, the inside of the main pumping chamber (the left ventricle) becomes smaller and stiffer. In many people, this thickened muscle blocks or restricts the flow of blood leaving the heart, a problem known as outflow obstruction. This extra strain can cause breathlessness, dizziness, and fatigue during everyday activities.

This clinical trial is studying an experimental medicine called aficamten (MYQORZO). In the heart, tiny proteins work together to make the muscle squeeze. In people with HCM, these proteins can work too hard. Aficamten is designed to calm this overactive squeezing, helping the heart muscle relax more easily. This allows the heart to fill with blood properly and pump it out without as much resistance.

Researchers want to see if starting aficamten early can make a meaningful difference to heart structure and health. Over the course of 54 weeks (just over a year), doctors will use advanced imaging—such as ultrasound scans (echocardiograms), MRI scans, and specialised PET scans—to look closely at heart thickness, scarring, and blood flow. They will also run regular blood tests to check markers of heart stress.

Because this is a Phase II study, it is focused on understanding both how well the medicine works and how safe it is. Finding treatments that treat the root cause of thickened heart muscle could help people with HCM avoid severe complications and stay active for longer.

Key takeaways

The LEAF-HCM trial tests a new tablet called aficamten for adults with hypertrophic cardiomyopathy.
Aficamten aims to ease heart muscle stiffness and improve blood flow out of the heart.
Participants take either aficamten or a dummy tablet (placebo) for 54 weeks.
Health is monitored closely using regular blood tests and specialised heart scans (MRI, PET, and ultrasound).
Participation is entirely voluntary and you can withdraw at any time.

Who may be eligible?

This study is open to adults aged 18 and over who have been diagnosed with hypertrophic cardiomyopathy (HCM). It includes both men and women whose heart muscle thickening is affecting blood flow through the heart.

To join, participants must be able to attend regular clinic visits and undergo standard hospital scans, including heart ultrasounds (echocardiograms) and MRI scans. Study doctors will run detailed health checks before anyone joins to make sure taking part is suitable and safe for them.

People might not be able to take part if their heart's pumping strength is already significantly weakened, if they have other severe medical conditions, or if they are unable to have an MRI scan (for example, due to certain metallic implants). A study doctor will discuss all medical criteria with you in detail.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

I am aged 18 or older.
I have been diagnosed with hypertrophic cardiomyopathy (HCM).
I am willing and able to take a daily tablet for about a year.
I am able to attend regular hospital check-ups and undergo scans, including MRI.
I do not have metal implants that prevent me from having an MRI scan.

Answer every question to see your result.

What does participation involve?

Taking part in the study lasts for roughly 54 weeks (just over a year). If you join, you will be randomly chosen to take either the study drug (aficamten tablets) or a dummy tablet (placebo) once daily. Neither you nor your study doctor will know which one you are receiving, ensuring the results are fair and unbiased.

Throughout the year, you will visit a specialist hospital clinic regularly. These visits will involve physical checks, blood tests, and heart tracings (ECGs). You will also have heart scans, including echocardiograms (ultrasound scans of your heart), cardiac MRI scans, and specialised PET/CT scans using a safe imaging dye to look for muscle scarring. You will be asked about your daily symptoms and any side effects you notice.

Potential risks and benefits

A potential benefit of taking part is that aficamten may improve your blood flow and reduce heart symptoms, although this cannot be guaranteed. You will also receive very close, expert health monitoring throughout the trial. However, there are potential risks, including side effects from the medication, such as the heart muscle relaxing too much and reducing pumping power. Scans and blood tests can also cause mild discomfort. Taking part is completely voluntary, and you are free to leave the trial at any time without your regular NHS care being affected.

Locations (1)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

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Unverified
Netherlands

Common questions

What is a placebo and why is it used?

A placebo is a dummy pill that looks identical to the real medicine but contains no active drug. Researchers use it to see whether changes in health are truly caused by aficamten or by other factors.

Will I definitely receive the active medicine?

No. Participants are placed into treatment groups at random, like flipping a coin. You have an equal chance of receiving either aficamten or the placebo.

What is the PET scan used for in this study?

The trial uses a specialised scan called a FAPI-PET/CT scan with a tiny amount of imaging dye. This helps doctors see active scarring and tissue changes inside the heart muscle.

Do I have to pay to take part?

No, clinical trials do not charge participants. All study medicines, scans, and tests are provided free of charge, and travel expenses to hospital visits are often reimbursed.

Can I leave the study if I change my mind?

Yes. You can stop taking part at any point, for any reason. Your decision will not change the standard of care you receive from your regular doctors.