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The Left Ventricular Mass Regression Paradox following Surgical Valve Replacement: A Real Phenomenon or a Mathematical Glitch?

The symptoms and adverse events in aortic stenosis (AS) are essentially determined by the imbalance between the increase in left ventricular (LV) hemodynamic load caused by valvular obstruction, on the one hand, and the capacity of the LV to overcome this increase in load on the other hand. Hence, AS results in increased LV systolic pressure and wall stress, which lead to hypertrophy of the cardiomyocytes and development of interstitial fibrosis. The pattern of this LV adaptive response to pressure overload in AS is, however, highly heterogeneous and includes concentric remodelling, concentric hypertrophy and eccentric hypertrophy. The pattern and magnitude of LV hypertrophy are influenced not only by AS severity but also by several other factors including age, sex, genetic factors, metabolic factors and the coexistence of coronary artery disease, hypertension, mitral regurgitation, or aortic regurgitation. For the same degree of AS, women tend to predominantly develop concentric remodelling/hypertrophy, whereas men are more prone to developing eccentric hypertrophy. Severe LV concentric remodeling or hypertrophy has been linked to worse myocardial function and increased risk of cardiac events and mortality both before and after aortic valve replacement (AVR). Recent studies suggest that the association between LV concentric hypertrophy and worse outcomes is stronger in women than in men. Residual LV hypertrophy after surgical or transcatheter AVR is associated with increased risk of mortality and heart failure re-hospitalization. The regression of LV hypertrophy thus represents an important goal of AVR. The presence of severe prosthesis-patient mismatch (PPM) and ensuing high residual transaortic gradients may hinder LV mass regression. Recent studies report that PPM is more frequent and more often severe following surgical AVR (SAVR) than transcatheter AVR (TAVR), and this translated into less LV mass regression and worse survival than those without PPM.