Effect of Mavacamten Therapy on Myocardial Systolic Function Assessed by 3D Echocardiography

Background: Myosin inhibitors represent a novel therapeutic strategy for obstructive hypertrophic cardiomyopathy (oHCM), directly targeting sarcomeric hypercontractility to reduce left ventricular outflow tract obstruction. Case Summary: Three patients with symptomatic oHCM enrolled in Italy's Early Access Program for mavacamten underwent 2D and 3D echocardiographic assessment at baseline and at 6 months. All experienced symptomatic improvement and left ventricular outflow tract obstruction reduction, accompanied by a modest decline in global left ventricular ejection fraction (LVEF) at 6 months follow-up. A 3-dimensional analysis revealed that LVEF reduction primarily involved mid and apical segments, while the basal function remained stable. Discussion: These findings suggest that mavacamten selectively attenuates hypercontractility in relatively preserved myocardial regions rather than inducing global systolic dysfunction. Three-dimensional echocardiography provided novel insights into regional contractile adaptation, offering potential guidance for individualized dosing and monitoring. Take-Home Messages: Mavacamten-induced LVEF decline reflects regional hypokinesia, not global dysfunction. Three-dimensional imaging enhances understanding of treatment response in oHCM.