Myqorzo (aficamten)

A once-daily pill approved by the FDA on December 19, 2025 for adults with symptomatic obstructive hypertrophic cardiomyopathy (HCM), to improve exercise capacity and symptoms. It belongs to the same drug class as mavacamten (Camzyos). Because it can weaken the heart's pumping, it carries a boxed warning, requires echocardiograms before and during treatment, and is available only through a restricted safety program called the Myqorzo REMS.

In obstructive HCM, the thickened heart muscle squeezes too hard, and the thick wall narrows the path blood takes out of the heart, called the left ventricular outflow tract (LVOT). Myosin is the motor protein inside heart muscle cells that pulls to produce each heartbeat. Aficamten attaches to cardiac myosin and reversibly turns down the force it generates, which reduces the over-squeezing and the blockage. In the main trial, the pressure difference caused by the blockage (the LVOT gradient) began to fall within 2 weeks. The same effect can lower the heart's pumping strength too far in some people, which is why echocardiogram results guide every dose change^[1].

Myqorzo has a boxed warning for heart failure. By reducing the heart's squeezing force, it lowers left ventricular ejection fraction (LVEF, the share of blood pumped out with each beat) and can cause heart failure from weak pumping (systolic dysfunction). Starting it is not recommended if LVEF is below 55%, the dose is lowered if LVEF falls below 50%, and treatment is paused if LVEF drops below 40% or heart failure symptoms appear. A serious illness such as a severe infection, or a new or uncontrolled irregular heartbeat such as atrial fibrillation, raises this risk. Because of it, Myqorzo is available only through the Myqorzo REMS program. It must not be taken with rifampin, and fluconazole, voriconazole, fluvoxamine and strong CYP2C9 inhibitors raise its levels and require dose changes. In the SEQUOIA-HCM trial, high blood pressure was the only side effect seen in more than 5% of patients and more often than on placebo (8% against 2%). A reversible drop in LVEF below 50% occurred in 4% of patients on Myqorzo against 1% on placebo; none of these needed a treatment pause or led to heart failure^[1].

Starts at 5 mg by mouth once a day, with or without food, swallowed whole. The dose can rise by 5 mg every 2 to 8 weeks, up to 20 mg once a day, based on echocardiogram results: it goes up only if LVEF is at least 55% and the Valsalva LVOT gradient (measured while bearing down) is 30 mmHg or higher. An echocardiogram is done 2 to 8 weeks after starting or any dose change, then every 6 months once the dose is stable, or every 3 months if LVEF is 50% to under 55%. After a pause for low LVEF, treatment restarts at 5 mg no sooner than 7 days later, once LVEF is back to at least 55%. A missed dose can be taken later the same day, but never 2 doses in 1 day. Tablets come in 5 mg, 10 mg, 15 mg and 20 mg and are dispensed only by REMS-certified pharmacies^[1].

Yes, Aficamten (Myqorzo) is FDA approved (2025) for the treatment of Familial Hypertrophic Cardiomyopathy.

Yes. The label requires an echocardiogram before starting, 2 to 8 weeks after starting or any dose change, and then every 6 months once the dose is stable, or every 3 months if LVEF is 50% to under 55%. The results decide whether the dose goes up, stays the same, goes down or is paused. Cytokinetics' copay program may cover the out-of-pocket cost of required echocardiograms for eligible commercially insured patients.

REMS stands for Risk Evaluation and Mitigation Strategy, an FDA-required safety program. Because Myqorzo can cause heart failure, only certified prescribers can prescribe it, only certified pharmacies can dispense it, and patients must enroll and keep up with echocardiogram monitoring. Details are at myqorzorems.com or 1-844-285-7367.

Both are cardiac myosin inhibitors for symptomatic obstructive HCM, both carry a boxed warning for heart failure, and both need echocardiogram monitoring and a REMS program. Myqorzo starts at 5 mg once daily with steps up to 20 mg, and rifampin is the one drug its label says must never be combined with it. Myqorzo was tested against placebo, not against Camzyos, so its label does not show whether either works better.

The main risk is heart failure from reduced pumping, which is why echocardiograms are required. In the SEQUOIA-HCM trial, high blood pressure was the most common side effect (8% against 2% on placebo), and a reversible drop in LVEF below 50% occurred in 4% against 1%, without heart failure.