Differential effect of antiobstructive therapy on mitral valve morphology in hypertrophic obstructive cardiomyopathy: a comparison of myosin inhibition and PTSMA therapy
M Chen, N Petri, M Dongiovanni, F Sahiti, V Cejka, S Frantz, U Hofmann, S Stoerk, C MorbachAbstract
Background
Mitral valve (MV) abnormalities are common in hypertrophic obstructive cardiomyopathy (HOCM) and are closely associated with left ventricular outflow tract (LVOT) obstruction via leaflet systolic anterior motion (SAM). The well-established interventional percutaneous transluminal septal myocardial ablation (PTSMA) and the novel myosin inhibitor mavacamten both can effectively reduce LVOT obstruction. However, there is little data on their impact on mitral valve morphology.
Purpose
To compare the effect of mavacamten and PTSMA treatment on mitral valve morphology in HOCM patients, respectively.
Methods
We included patients prospectively enrolled in a HCM registry. We identified HOCM patients who either had undergone PTSMA or were treated with mavacamten. All patients underwent clinical assessment and standardized transthoracic echocardiography (TTE) in the cardiology department of a tertiary care University Hospital. During TTE, we acquired a 3D volume of the MV and consecutively performed a semi-automated quantitative analysis of MV annulus and leaflets from stored images using EchoPAC (4D Auto MVQ, GE Healthcare). Assuming treatment-specific maximal LVOT reduction, mavacamten patients and PTSMA patients underwent follow-up after six and twelve months, respectively.
Results
A total of 51 symptomatic HOCM patients was included in our analysis. 12 patients received mavacamten and 39 patients had undergone PTSMA. The two groups were equal in age, NYHA functional class and NT-proBNP level, as well as regarding TTE parameters including resting und provoked LVOT gradients, the presence of systolic anterior motion (SAM), left ventricular ejection fraction, E/e’ and left atrial volume index (table). However, the mavacamten group demonstrated significantly larger mitral annulus dimensions than the PTSMA group, including annulus area (p = 0.016), anterior to posterior diameter (p = 0.049), annulus perimeter (p = 0.009) and annulus height (p = 0.041) (table). Counting from start of treatment, the mavacamten group at 6 months and the PTSMA group at 12 months both demonstrated a significant reduction in LVOT gradients under resting and provoked conditions, respectively (figure). Furthermore, the mavacamten group exhibited significant reverse remodeling of the mitral valve leaflets, reflected in a reduction of leaflet tenting height (p = 0.029) and active anterior leaflet length (p = 0.036) (figure).
Conclusions
Both, myosin inhibition and PTSMA significantly reduced LVOT obstruction in HOCM patients . Notably, our patients on mavacamten further demonstrated a significant reduction in leaflet tenting height and active anterior leaflet length, both components contributing to SAM. Our data suggest that myosin inhibition might induce beneficial changes in MV structure in addition to the reduction of the LVOT gradient, but deserve validaiton in larger cohorts.Baseline characteristicsFor image description, please refer to the figure legend and surrounding text.Changes in echocardiographic parametersFor image description, please refer to the figure legend and surrounding text.