Abstract 12372: Longitudinal Strain of Papillary Muscles in Degenerative Mitral Valve Disease: Predictor of Surgical Result?

Abstract

Introduction: In this study, we examined the longitudinal strain of primary papillary muscles (anterolateral and posteromedial) of the mitral valve and the left ventricle (LV) before and after repair of the posterior leaflet in isolated posterior prolapse. The hypothesis of the study was based on the principle of preservation of mechanical energy within the mitral valve circuit, where a successful mitral valve repair is achieved when the global strain of the papillary muscles is equal to zero.

Methods: Sixty-four patients with posterior leaflet prolapse and severe mitral regurgitation were recruited in the period 2007-2010. They were examined with 2D and real time three dimensional echocardiography, before and 6 months after mitral valve repair and the analysis of data was performed off-line. Strain of papillary muscles and the LV were indexed to LV end-diastolic volume (LVEDV), as per the Frank-Starling theory. A control group of 20 healthy volunteers were used for comparison.

Results: Post repair, there was reduction of volumes (LVEDV: before: 173.6 ± 52.5 mls vs. after: 142.6 ± 49.5 mls, p<0.01) without significant change of ejection fraction. Before repair, longitudinal strain of the posteromedial muscle was disproportionally high (-12.6% ± 5.2%) when compared to the anterolateral muscle (-4.9% ± 2.2%). Post repair, 56 patients with a successful repair, had global strain of papillary muscles close to zero (-0.97% ± 1.05%) when compared to 8 patients with significant regurgitation 6 months post repair (-17.6% ± 6.6%). It is demonstrated that when the global strain of papillary muscles before repair is ≥ -9% there is sensitivity 100% and specificity 76.8% for development of hemodynamically significant regurgitation post repair. Interobserver reproducibility for papillary muscle longitudinal strain was examined: anterolateral: r=0.73, p<0.001, mean bias=0.87, SD of bias=1.7.

Conclusions: This study demonstrates that a disproportionally increased papillary muscle strain post repair is a predictor of recurrent mitral regurgitation. Longitudinal strain of papillary muscles may be an important prognostic imaging tool for mitral valve repair.