Eccentric remodeling in patients undergoing mitral valve repair due to severe degenerative mitral regurgitation: impact of relative wall thickness on clinical outcomes

Abstract

Abstract Background Left ventricular (LV) volume overload in mitral regurgitation (MR) leads to a progressive increase in LV mass. Eccentric hypertrophy is defined as the relative wall thickness (RWT) <0.43, and LV hypertrophy is a frequently observed LV remodeling phenotype in patients with severe MR. However, the prognostic impacts of RWT in these patient groups are not well known. We tested the relationship between RWT and clinical outcomes in severe MR patients undergoing MV repair (MVR). Methods A total of 979 consecutive adult patients with severe degenerative MR and eccentric hypertrophy (55 ± 13 years, 616 males) who underwent MVR were retrospectively analyzed. The study population was stratified by the median RWT value (RWT=0.34) on baseline echocardiography [the lesser RWT group (RWT< 0.34 (n=651)) and the greater RWT group (RWT ≥0.34 (n = 328)). Results The patients in the lesser RWT group were younger (54±13 vs. 57±13, p<0.001) and had a significantly higher prevalence of hypertension and diabetic mellitus than those in the greater RWT group. The greater RWT group had significantly lower indexed LV systolic dimension, thicker ventricular walls, and higher LV ejection fraction as compared with those in the lesser RWT group. In Kaplan-Meier analysis, the greater RWT group had a significantly higher incidence of all-cause death (6.4% vs. 2.3%; log-rank p<0.001) and cardiac death (3.0% vs. 0.9%; log-rank p = 0.01) at five years after MVR than in the low RWT group. RWT≥0.34 was independently associated with higher all-cause and cardiac mortality in the multivariate Cox regression analysis. In subgroup analysis, RWT≥0.34 was associated with worse outcomes in men (P <0.001) but not in women (P = 0.23). Moreover, hypertensive patients in the greater RWT group showed the worst outcomes as compared with the three other groups. Conclusions We concluded that excessive ventricular hypertrophy, manifested as an increased relative wall thickness, is associated with a significantly increased risk of postoperative mortalities after mitral valve repair in patients with severe degenerative MR and eccentric hypertrophy. We also found that eccentric remodeling patterns and clinical outcomes differ according to sex and the presence of hypertension.