Initial insights into left ventricular mechanics of hypertrophic cardiomyopathy patients during follow up of mavacamten therapy

Abstract Introduction Mavacamten is a novel therapy for hypertrophic obstructive cardiomyopathy. Left ventricular (LV) ejection fraction (EF) has been used for monitoring of left ventricular systolic function during therapy. Currently there is limited data on advanced functional parameters based on speckle tracking strain values, such as global longitudinal strain (GLS) , myocardial work (MW) or 3D echocardiography. MW is an emerging method which incorporates left ventricular pressure and provides multiple parameters based on a LV pressure-strain loop. This study aimed to provide some insights into temporal changes of left ventricular deformation during mavacamten therapy. Purpose The purpose of this study was to examine left ventricular global and segmental strains and myocardial work parameters during mavacamten therapy. Methods The study involved 10 (5 women, 50%; aged 57±11 years) cases of mavacamten initiation and echocardiographic follow up (10 patients followed up to visit 1: 48±4.3 days, and 9 patients followed up to visit 2: 129±2.9 days). Comprehensive 2D and 3D resting echocardiography was performed. Speckle tracking based left ventricular strain values were measured. With a previously validated method left ventricular pressure was corrected for measurement of myocardial work parameters. The regional 2D based, LV strain and MW parameters were also examined. Results At the first follow up left ventricular obstruction gradient was already significantly lower compared to baseline and remained decreased at the second follow up (113±36 vs. 37±35 vs. 20±19 mmHg). EF or GLS did not differ significantly between visits (63.8±5.1 vs. 62.5±4.7 vs. 60.9±4.4 %, and -14.5±2.9 vs. -13.9±2.3 vs. -15.6±2.3 % respectively). Global Work Index (GWI) (2026±364 vs. 1588±351 vs. 1578±219 mmHg) and Global Constructive Work (2617±395 vs. 2010±400 vs. 1959±296 mmHg) significantly reduced at both visits when compared to baseline, but not between follow up visits. Global Wasted Work (GWW) (280±117 vs. 245±125 vs. 186±49) and Global Work Efficiency (GWE) (85.6±3.9 vs. 86.6±5.2 vs. 88.8±7.2 %) did not change significantly during follow up, similarly to no changes in 3D based strain, and rotational parameters. Peak Strain Dispersion, (102.8±40.7 vs. 93.8±35.3 vs. 75.9±29.8 ms). 3D based LV Mass (257±75 vs. 248±44 vs. 226±71 g) and Mass Index (137±44 vs. 131±42 vs. 119±41 g/m2) decreased at visit 2, but not at visit 1. The segmental analysis proved significant changes during follow-up compared to baseline in longitudinal strain (2 segments), MW (12 segments) wasted work (1 segment) and work efficiency (2 segments). Conclusions Among left ventricular functional parameters myocardial work has shown the most statistically significant differences during follow up, highlighting the reduction of the LV workload. The analysis of segmental data has shown a heterogeneous pattern of changes, primarily in MW.