Mavacamten (Camzyos) is an innovative drug indicated for the treatment of symptomatic obstructive hypertrophic cardiomyopathy, and it belongs to the class of cardiac myosin inhibitors. As a prescription medication with a unique mechanism of action and notable efficacy, its administration is associated with specific risks and strict monitoring requirements.

What Are the Precautions for Mavacamten (Camzyos) Administration?

Risk of Heart Failure

This drug may induce cardiac systolic dysfunction, leading to heart failure.

Initiation of treatment is absolutely not recommended for patients with a left ventricular ejection fraction (LVEF) of less than 55%.

At any time during treatment, if LVEF drops below 50%, or if the patient develops heart failure symptoms (such as new or worsening dyspnea, chest pain, fatigue, palpitations, lower extremity edema, etc.) or experiences clinical deterioration, medication must be immediately discontinued.

Absolutely Contraindicated Concomitant Medications

Strong CYP2C19 inhibitors (e.g., fluconazole, fluvoxamine), moderate to strong CYP2C19 inducers, or moderate to strong CYP3A4 inducers (e.g., rifampicin, carbamazepine, phenytoin sodium, St. John's wort).

Concomitant use may cause a sharp increase in the risk of heart failure or loss of therapeutic efficacy.

Dose Adjustment Requiring Caution

When coadministered with weak to moderate CYP2C19 inhibitors (e.g., omeprazole, esomeprazole) or moderate to strong CYP3A4 inhibitors (e.g., verapamil, diltiazem, ketoconazole), the dose of mavacamten needs to be adjusted and close monitoring should be strengthened.

Patients must inform their physicians of all medications they are taking, including over-the-counter drugs and dietary supplements.

Embryo-Fetal Toxicity

Based on animal study data, mavacamten may cause fetal harm.

Females of reproductive potential must confirm non-pregnancy before initiating treatment, and adopt effective contraceptive measures during treatment and for 4 months after the last dose.

Mavacamten may reduce the effectiveness of certain progestin-containing combined hormonal contraceptives. It is recommended to consult a physician to select an appropriate contraceptive method.

Medication Monitoring for Mavacamten (Camzyos)

Pre-Treatment Assessment

Cardiac function evaluation: Before starting treatment, baseline LVEF and left ventricular outflow tract (LVOT) gradient under Valsalva maneuver must be measured via echocardiography. An LVEF < 55% is a contraindication for treatment initiation.

Pregnancy status confirmation: Conduct pregnancy testing for all female patients of reproductive potential.

Comprehensive medication review: Evaluate all concomitant medications of the patient to avoid contraindicated combinations.

Regular Echocardiographic Examinations

During the treatment initiation and dose adjustment phase, LVEF and LVOT gradient need to be re-examined regularly (e.g., at Week 4, Week 8, and Week 12).

After entering the maintenance phase, regular assessments should still be performed every 3–6 months.

If LVEF < 50% is detected during any visit, treatment must be discontinued immediately.