Comparison of temporal changes in left atrial and left ventricular strain after septal myectomy, alcohol septal ablation, and cardiac myosin inhibitor

Abstract Aims Cardiac myosin inhibitors (CMIs) have emerged as an alternative to septal reduction therapy (SRT) for obstructive hypertrophic cardiomyopathy (oHCM). However, comparative data on the time-trajectory of myocardial functional adaptation after septal myectomy (SM), alcohol septal ablation (ASA), and CMI are lacking. We compared temporal changes in echocardiographic parameters including LV global longitudinal strain (LVGLS) and LA reservoir strain (LASr) across these treatment strategies. Methods and Results In this single-center retrospective cohort, symptomatic oHCM patients treated with SM (n=22), ASA (n=11), or CMI (n=47) underwent serial echocardiography with deep-learning–based automated strain analysis. Primary outcomes were temporal changes in LVGLS and LASr. Mixed-effects models adjusted for baseline clinical and echocardiographic variables were used to assess time-trajectories for up to 24 months. Treatment success rates were 86.4% (SM), 72.7% (ASA), and 93.6% (CMI). LVOT gradients were similarly reduced across groups. LVEF showed a subtle early decline after CMI (adjusted P-for-interaction=0.019). LVGLS gradually improved after SM and ASA but remained unchanged with CMI. LASr significantly improved after SM, showed minimal change after ASA, and demonstrated late attenuation beyond 9–12 months in the CMI group (adjusted P=0.029). Conclusions Despite comparable LVOT gradient reduction, myocardial functional adaptation differed across therapies. Conventional SRT was associated with progressive improvement in LV and LA strain, whereas CMI therapy showed stable LVGLS with subtle early LVEF decline and late attenuation of LASr. These findings underscore the importance of longitudinal deformation imaging during CMI therapy and support reappraisal of SRT in selected patients requiring durable long-term management.