Monitoring treatment with cardiac myosin inhibitors in symptomatic obstructive hypertrophic cardiomyopathy

Purpose of review Cardiac myosin inhibitors (CMIs) represent a major milestone in the treatment of patients with symptomatic obstructive hypertrophic cardiomyopathy. The objective of this review is to discuss the mechanisms of action, clinical trial evidence, safety profile and monitoring of CMIs, which are important to the implementation of these drugs in clinical practice. Recent findings Mavacamten and aficamten have both been shown to substantially improve left ventricular outflow tract gradients, biomarkers and symptoms in patients with obstructive hypertrophic cardiomyopathy. Both agents are well tolerated with few adverse events in clinical trial follow up. Transient reductions in left ventricular ejection fraction may be associated with both mavacamten and aficamten but respond to dose reduction. Summary There is now robust clinical trial evidence base to support the use of mavacamten for patients with symptomatic obstructive hypertrophic cardiomyopathy. Generation of long-term safety and efficacy data and exploring applications of CMI to nonobstructive cardiomyopathy and heart failure with preserved ejection fraction represent important next steps.