Cardiac Myosin inhibitor improves mid-ventricular obstruction in hypertrophic cardiomyopathy
L Luan, H Chen, T Wang, J Zhang, M Han, Y Liu, M Sun, X ShuAbstract
Background
Cardiac Myosin Inhibitor effectively reduces left ventricular outflow tract (LVOT) gradients in obstructive hypertrophic cardiomyopathy (HOCM), but its effect on mid-ventricular obstruction (MVO) remains unclear. We investigated the impact of mavacamten on hemodynamics and left ventricular remodeling in patients with isolated MVO and mixed obstruction (MVO plus LVOT obstruction).
Methods
We retrospectively studied HOCM patients treated with mavacamten for ≥3 months at our center between October 2024 and May 2025. Among 356 treated patients, 52 had isolated MVO and 22 had mixed obstruction. Echocardiography was performed at baseline and after 3 months of initial-dose therapy (mavacamten 2.5 mg once daily). LVOT and mid-ventricular pressure gradients were assessed at rest and with provocation. Gradient reduction rate was calculated as (baseline − follow-up)/baseline × 100%. Changes in left ventricular end-diastolic diameter (LVEDD), end-systolic diameter (LVESD), ejection fraction (LVEF), and interventricular septal thickness (IVST) were also analyzed.
Results
In isolated MVO, mid-ventricular gradients decreased significantly at rest (43.60±20.42 vs 30.12±18.75 mmHg) and with provocation (58.91±17.52 vs 42.57±21.25 mmHg; both P<0.05). IVST decreased (15.44±4.39 vs 14.37±3.44 mm, P<0.05), whereas LVESD increased (28.81±3.79 vs 30.25±3.09 mm, P<0.05). LVEF decreased slightly but remained normal (64.40±4.19% vs 62.77±3.93%, P<0.05). In mixed obstruction, both LVOT and mid-ventricular gradients decreased significantly at rest and with provocation (all P<0.05). IVST decreased (18.09±2.72 vs 17.05±2.46 mm, P<0.05), LVEDD increased (43.09±3.98 vs 44.86±4.00 mm, P<0.05), and LVEF remained unchanged (64.91±4.11% vs 63.41±4.85%, P=0.147). In this group, the reduction in mid-ventricular gradients was comparable to that in LVOT gradients at rest (55.88±28.92% vs 52.43±21.16%, P=0.430) and with provocation (57.18±19.34% vs 49.84±34.64%, P=0.135). In the mixed obstruction group, the reduction in LVM-PG was comparable to that in LVOT-PG both at rest (55.88±28.92% vs 52.43±21.16%, P=0.430) and with provocation (57.18±19.34% vs 49.84±34.64%, P=0.135).
Conclusions
Mavacamten significantly reduces mid-ventricular gradients in HOCM, regardless of concomitant LVOT obstruction. In mixed obstruction, it improves both LVOT and mid-ventricular gradients with favorable remodeling and preserved LVEF. In isolated MVO, although gradients improve significantly, mild LVEF reduction and LVESD increase suggest closer monitoring of systolic function. In mixed obstruction, the magnitude of mid-ventricular gradient reduction is comparable to that of LVOT gradient reduction.