Echocardiographic parameters of left ventricular diastolic dysfunction, left atrial volumes and left atrial function improves in obstructive hypertrophic cardiomyopathy during mavacamten treatment

Background/Objectives The selective cardiac myosin inhibitor mavacamten, is indicated for the treatment of symptomatic, NYHA II-III class adult patients with obstructive hypertrophic cardiomyopathy [oHCM, ≥ 50 mmHg resting or provokable left ventricular outflow tract (LVOT) peak gradient]. As real-world data on the efficacy of the drug are relatively scarce, we aimed to investigate the effect of mavacamten treatment on echocardiographic parameters of left ventricular (LV) diastolic dysfunction and left atrial (LA) function. Patients and Methods Thirty-nine oHCM patients [21 men (54%), mean age: 56±11 years] were treated with mavacamten. In addition to recording the main demographic and clinical parameters, complete standard, 2D-speckle tracking and 3D volumetric and speckle tracking echocardiographic examination was performed in four-week intervals of treatment until 12 weeks (W12). Results With the decrease of the resting peak LVOT gradient (average reduction of -57 mmHg at W12, <0.0001)echocardiographic parameters of transmitral flow, E and A waves, and E/A ratios did not change significantly during treatment. A significant linear trend was identified with respect to changes of the E wave (p=0.0248). Lateral e’ and E/e’ displayed significant favourable changes already at W8 (lateral e’: 6.5 vs. 7.6 cm/s, p=0,0038; E/e’: 17.2 vs. 14.3, p=0.0287), and showed further change until W12 (lateral e’: to 7.7 cm/s, p=0.0042; E/e’: to 14.3, p=0.0117). Left atrial volume (LAV) and volume index (LAVI) values showed a significant regression until W12 (LAV: 127 vs. 109 ml; p=0.0002; LAVI: 64 vs. 55 ml/m2; p=0.0008). 3D atrial volumes also decreased significantly already at W08 and until W12 (LA maximal volume: 106 vs. 96 vs. 91 ml, p=0.0062; LA minimal volume: 64 vs. 54. vs. 53 ml, p=0.0020; LA preA volume: 86 vs. 77 vs. 74 ml, p=0.0120). Atrial EF showed a significant linear trend for increase (p=0.0123). Left atrial reservoir strain (LASr) showed significant linear trend for increase (p=0.0079), the change became significant at W12 (15.8 vs. 17.5, p=0.0387). 2D left atrial contractile, conduit strain and 3D LA strains showed no significant change. Conclusions In parallel with the reduction of the LVOT gradient, mavacamten led to significant favorable changes in echocardiographic parameters of LV diastolic dysfunction, LA volumes and LA function already in 8-12 weeks.