Myqorzo (Aficamten) for Heart Condition

Myqorzo (aficamten) is a prescription medication approved by the U.S. Food and Drug Administration (FDA) to treat adults with symptomatic obstructive hypertrophic cardiomyopathy (oHCM), a heart condition that makes it harder for blood to flow out of the heart.

How Myqorzo Works and How It’s Taken

Myqorzo is a type of medicine called a cardiac myosin inhibitor. It works by reducing the activity of myosin, a protein that helps the heart muscle contract. This reduces the force of the heart’s contractions and helps reduce the blockage that makes it harder for blood to flow out of the heart.

Doctors prescribe Myqorzo when adults have symptomatic oHCM. Myqorzo helps improve symptoms and the ability to be physically active.

Myqorzo is available only through a special safety program called the Myqorzo REMS Program.

Myqorzo comes as a tablet taken by mouth. It can be taken with or without food. Swallow the tablet whole.

Typical Dosing for oHCM

The recommended starting dose of Myqorzo is 5 milligrams by mouth once daily, at about the same time each day.

Doctors may increase the dose by 5 milligrams every two to eight weeks, up to a maximum of 20 milligrams once daily. The maintenance dose is based on heart ultrasound tests called echocardiograms. These tests help doctors check how well the heart pumps blood and how much blood flow is blocked.

Doctors may lower the dose or temporarily stop treatment if heart function decreases or signs of heart failure develop.

If treatment is stopped because the heart’s pumping function becomes too low, it must be stopped for at least seven days. Treatment can restart when the heart’s left ventricular ejection fraction (LVEF), a measure of how well the heart pumps blood, reaches at least 55 percent. Treatment then restarts at 5 milligrams once daily.

This information is based on prescribing information, but your healthcare provider may tailor your treatment plan. Always follow their guidance.

Myqorzo Side Effects

In a clinical study of Myqorzo, the most common side effect was hypertension (high blood pressure), which occurred in about 8 percent of people taking it.

Serious Side Effects and Warnings

Myqorzo can cause serious side effects that may require immediate medical attention. These include:

Heart failure — The heart cannot pump with enough force, which can be life-threatening.

Myqorzo has a boxed warning, the FDA’s strongest safety warning, for heart failure. A boxed warning does not mean the drug is unsafe for everyone or that everyone faces the same level of risk.

Get medical help right away if you think you are having a serious reaction.

How To Save on Myqorzo

Cytokinetics, the manufacturer of Myqorzo, offers the Myqorzo & You Patient Support Program. Eligible people with commercial insurance may pay as little as $5 for Myqorzo.

The program also offers a free trial of up to 60 days for eligible people with government insurance. For eligible people with commercial insurance, the Bridge Program may provide up to 12 months of medication after an initial insurance denial. An Echocardiogram Copay Savings Program may reduce eligible echocardiogram costs to $0.

To learn more, visit the Myqorzo & You Patient Support Program webpage or call 833-697-6796.

What To Know Before Taking Myqorzo

Before starting Myqorzo, your doctor will:

Check your heart function using a heart ultrasound test called an echocardiogram.
Measure your LVEF, which shows the percentage of blood your heart’s main pumping chamber pushes out with each beat.
Review your LVEF results. Starting Myqorzo is not recommended if your LVEF is below 55 percent.

Before starting Myqorzo, tell your doctor if you have any allergies to aficamten or any ingredients in Myqorzo.

Tell your doctor about all medicines you take, including prescription drugs, over-the-counter medicines, vitamins, and herbal supplements. Some medicines can increase the amount of Myqorzo in your blood and raise your risk of heart failure.

Be sure to tell your doctor if you take:

Fluconazole, if taken for more than three days
Voriconazole
Fluvoxamine

Do not take Myqorzo with rifampin.

If you miss a dose of Myqorzo, take it as soon as possible on the same day. Take your next dose at the usual time the following day. Do not take two doses on the same day.

Tell your doctor if you are pregnant or plan to become pregnant. It is not known whether Myqorzo can harm a developing baby. Tell your doctor if you become pregnant during treatment or within three weeks after your last dose.

There is a pregnancy safety study for Myqorzo. Your doctor should report your exposure during pregnancy to Cytokinetics.

Tell your doctor if you are breastfeeding or plan to breastfeed. It is not known whether Myqorzo passes into breast milk. Talk with your doctor about the best way to feed your baby during treatment.

Community FAQs

These answers are fact-checked by our editorial staff.

How effective is Myqorzo for obstructive hypertrophic cardiomyopathy?

In a 24-week clinical study involving 282 adults with symptomatic oHCM, Myqorzo helped improve physical activity, symptoms, and the blockage that makes it harder for blood to flow out of the heart compared with a placebo (an inactive treatment).

The study found that:

Exercise ability improved — People taking Myqorzo had an average improvement in peak oxygen uptake that was 1.7 milliliters per kilogram of body weight per minute greater than those taking placebo. This measurement shows how much oxygen the body can use during exercise.
Heart-related physical limitations improved — After 24 weeks, 58.5 percent of people taking Myqorzo improved by at least one New York Heart Association (NYHA) class, compared with 24.3 percent taking placebo. NYHA classes describe how much heart symptoms limit physical activity.
Heart-related health scores improved — People taking Myqorzo had a 7.3-point greater improvement in scores measuring symptoms and their effects on daily activities compared with those taking placebo.
Blockage affecting blood flow out of the heart decreased — Myqorzo reduced the pressure difference caused by the blockage by 48.8 millimeters of mercury more than placebo after 24 weeks. This was measured during a test in which people bear down to help doctors assess blood flow out of the heart.

How long does Myqorzo take to work for obstructive hypertrophic cardiomyopathy?

In the clinical study, reductions in the blockage affecting blood flow out of the heart were seen two weeks after people started taking Myqorzo. These reductions continued through week 8 and lasted through the 24-week study.

Levels of NT-proBNP, a substance in the blood that can help doctors assess strain on the heart, also decreased starting at week 2 and remained lower through week 24.

The study shows when changes in heart measurements were first seen, but it does not establish exactly when people begin to notice symptom relief.

Does Myqorzo interact with other medicines?

Yes. Myqorzo can interact with certain medicines. Some interactions can increase the risk of heart failure, while others can make Myqorzo less effective.

These include:

Fluconazole — A medicine used to treat fungal infections. Taking it for more than three days may require changes to your Myqorzo treatment.
Voriconazole — A medicine used to treat fungal infections. Taking it with Myqorzo may increase the risk of heart failure.
Fluvoxamine — A medicine used to treat certain mental health conditions. Taking it with Myqorzo may increase the risk of heart failure.
Carbamazepine — A medicine used to treat seizures and certain other conditions that may make Myqorzo less effective. Stopping carbamazepine while taking Myqorzo may increase the risk of heart failure.

Do not take Myqorzo with rifampin, an antibiotic used to treat certain bacterial infections, including tuberculosis. Rifampin can lower the amount of Myqorzo in your blood and make it less effective.

Tell your doctor about all medicines you take, including prescription medicines, over-the-counter medicines, vitamins, and herbal supplements.

Do not start, stop, or change the dose of any medicine without telling your healthcare provider. Your doctor may need to adjust your Myqorzo dose and check your heart function more often.