Effect of Mavacamten on Echocardiographic Features in Symptomatic Patients With Obstructive Hypertrophic Cardiomyopathy

<p><strong>Background: </strong>EXPLORER-HCM demonstrated that mavacamten, a cardiac myosin inhibitor, improves symptoms, exercise capacity, and left ventricular outflow tract (LVOT) obstruction in patients with obstructive hypertrophic cardiomyopathy (oHCM).</p> <p><strong>Objectives: </strong>The purpose of this study was to evaluate mavacamten's effect on measures of cardiac structure and function and its association with changes in other clinical measures.</p> <p><strong>Methods: </strong>Key echocardiographic parameters from serial echocardiograms over 30 weeks were analyzed from 251 symptomatic obstructive hypertrophic cardiomyopathy (oHCM). patients out of which 123 were on mavacamten and 128 were on placebo [n = 128])</p> <p><strong>Results: </strong>More patients on mavacamten (80.9%; n = 76 of 94) vs placebo (34.0%; n = 33 of 97) showed complete resolution of mitral valve systolic anterior motion after 30 weeks (difference, 46.8%; P &lt; 0.0001).</p> <p>Mavacamten also improved measures of diastolic function vs placebo, including left atrial volume index (LAVI) (mean change from baseline of -7.5 mL/m2 [P &lt; 0.0001) and lateral E to e' (mean change of -3.8 vs 0.04 in placebo with P &lt; 0.0001).</p> <p>Among mavacamten-treated patients, improvement in resting, Valsalva, and post-exercise LVOT gradients, Left Atrial Volume Index (LAVI), and lateral E to e' ratio was associated with reduction in N-terminal pro-B-type natriuretic peptide (P ≤ 0.03 for all). Reduction in Left Atrial Volume Index was associated with improved peak exercise oxygen consumption (P = 0.04).</p> <p><strong>Conclusions: </strong>Mavacamten significantly improved measures of left ventricular diastolic function and systolic anterior motion. Improvement in left ventricular outflow tract obstruction, Left Atrial Volume Index, and E to e' ratio was associated with reduction in a biomarker of myocardial wall stress (N-terminal pro-B-type natriuretic peptide). These findings demonstrate improvement in important markers of the pathophysio