Mavacamten: a novel avenue towards hypertrophic obstructive cardiomyopathy

Abstract

Hypertrophic obstructive cardiomyopathy (HCM) is the most common heterogeneous genetic cardiovascular disorder. Its pathophysiology involves left ventricular hypertrophy, increased fibrosis, hypercontractility, and reduced compliance. The symptomatic obstructive HCM presents as dyspnoea, syncope, chest pain, palpitations, arrhythmias, or sudden death, usually after provocative manoeuvres like exercise. Until April 2022, treatment options were disease non-specific like Beta blockers, Cardio-selective Calcium Channel Blockers, Dipyridamole, and Ranolazine. Mavacamten is a first-in-class, FDA-approved drug molecule for HCM. It works by selective and reversible inhibition of the cardiac myosin ATPase thereby decreasing the formation of actin- myosin cross- bridges in systole and diastole. The excessive actin-myosin cross-bridging is the hallmark of disease and is responsible for the compromised functioning of the heart in both the systole and diastole phase due to left ventricular outflow tract (LVOT) obstruction and increased ventricular filling pressure respectively. Mavacamten acts by producing super-relaxed state of heart which is then translated into decreased LVOT obstruction and improved cardiac filling pressures thereby improving the functional capacity and symptoms in patients with New York Heart Association (NYHA) stage II, and III symptomatic or obstructive heart failure. Mavacamten is administered orally 2.5-15 mg per day with titration guided by lab investigations and clinical symptoms. Its bioavailability is 85%, undergoes metabolism by CYP2C19 and CYP3A4 and is excreted mainly in urine. It is also an enzyme inducer and shows considerable drug interactions. Common adverse effects are dizziness and syncope. Sometimes the drug may worsen heart failure or completely block ventricular function. Mavacamten has raised hopes for the possibility of managing this potentially lethal intrigue disorder with medicines alone.