The impact of complete versus partial preservation of the sub-valvular apparatus on left ventricular function in mitral valve replacement.

Introduction: In mitral valve replacement (MVR), sudden increases in afterload and disruption of the annular-chordal-papillary-left-ventricular wall causes left ventricular (LV) dysfunction in the early postoperative period. Preservation of the posterior mitral leaflet apparatus (MVR-P) has a favorable outcome on LV function. However, there is paucity of data on the impact of complete preservation of the sub-valvular apparatus (MVR-C).

Objective: We investigated the impact of MVR-P and MVR-C on baseline and 3-months postoperative LV ejection fraction (EF) and global longitudinal strain (GLS).

Methods: We retrospectively analyzed a cohort of 29 MVR-P and 19 MVR-C patients with complete echocardiography data at our unit, who were operated between 2008 and 2017. Between-group changes in LVEF and GLS were compared using independent sample T-test.

Results: Median age was 59 years (IQR 50-69 years). Baseline LVEF was 58% (51%- 60%). Baseline GLS was -18.4 (-21.2 to -15.5). There were no significant between-group differences between all baseline demographics and echocardiographic markers. There was significantly higher absolute postoperative LVEF in MVR-C patients (p = 0.029). There was also significant worsening in LVEF (p = 0.0121) and GLS (p < 0.0001) after MVR-P and not MVR-C, suggesting no reduction in LV function post-MVR-C but a reduction post-MVR-P. There was significantly less postoperative worsening of GLS per patient in MVR-C group as compared to the MVR-P group (p = 0.023), indicating better preservation of LV function. There was also a smaller decline in LVEF per patient in the MVR-C as compared to the MVR-P group, although not statistically significant (p = 0.23).

Conclusion: MVR with complete preservation of the sub-valvular apparatus shows a favorable impact on the longitudinal function of the heart at 3 months. Further studies with larger patient numbers are indicated to investigate the long-term results of this surgical approach.