Instructions on contraindications for the use of Mavakatai/Mefantuo

Since mavacamten directly acts on the myocardial contractile system, its drug safety assessment is highly dependent on the basic cardiac function status of patients with hypertrophic cardiomyopathy (HCM). Therefore, in clinical applications, it is particularly critical to identify those who are contraindicated or should be used with caution. Based on the medication experience and the information in the instructions, the following groups of people are generally considered unsuitable or need to use Mavakate with a high degree of caution.

First, patients with significant left ventricular systolic dysfunction are usually classified as contraindications or not recommended for use. The core mechanism of Mavaceta is to reduce myocardial contractility. For patients with low ejection fraction or symptoms of heart failure, further inhibition of contraction may increase the risk of cardiac dysfunction. Therefore, cardiac ultrasound results need to be fully evaluated before medication to ensure that the left ventricular ejection fraction is within a safe range.

Secondly, use should be carefully considered in patients with severe arrhythmias, especially uncontrolled atrial fibrillation or ventricular arrhythmias. Although Mavaceta does not directly act on electrophysiological channels, changes in myocardial contractility may indirectly affect the stability of cardiac electrical activity. Overseas experts generally recommend that it is not advisable to start treatment with this drug rashly before the arrhythmia is effectively controlled.

In addition, Mavaceta is generally not recommended for pregnant and lactating women. Currently, there is limited clinical data on its effects on embryonic development and milk secretion. Based on potential risk assessment, overseas drug guidance tends to adopt a conservative strategy. Women of childbearing age should fully communicate their fertility plans before treatment and take reliable contraceptive measures.

In terms of drug interactions, patients who have long-term use of potent CYP450 enzyme inhibitors or inducers are also considered to be users with caution. Mavaceta is mainly metabolized by the liver, and the combined use of drugs that affect metabolic pathways may lead to abnormal fluctuations in drug concentration in the body, thereby increasing the risk of cardiac function suppression or insufficient efficacy.

Reference materials:https://bnf.nice.org.uk/drugs/mavacamten/