Magnetic Resonance Imaging With 3-Dimensional Analysis of Left Ventricular Remodeling in Isolated Mitral Regurgitation

Abstract

Background Although surgery is indicated in patients with mitral regurgitation (MR) when left ventricular (LV) end-systolic (ES) dimension (D) is >40mm, LV ejection fraction (EF) may decrease post-mitral valve surgery. We hypothesize that significant LV remodeling pre-surgery is not reflected by standard echocardiographic parameters measured at the base of the heart. Methods and Results 94 patients (54±11 years, 38% female) with degenerative isolated MR underwent cine-magnetic resonance imaging (MRI) with tissue tagging and three-dimensional analysis. In 51 control subjects (44±14 years, 53% female), the relation between LVES volume (V) and LVESD was quadratic, while in 94 MR patients this relation was cubic, indicating greater increase in LVESV per LVESD amongst MR patients. Moreover, MRI LVESV from summated serial short axis slices was significantly greater than LVESV using the Bullet formula in MR patients, attributed to a more spherical remodeling distal to the tips of the papillary muscles (P<0.001). 35 patients underwent mitral valve repair per current guideline recommendations. LVEF decreased from 61±7 to 54±8 % (P<0.0001) and maximum shortening decreased significantly below normal at 1-year post-operatively (P<0.0001). Despite normalization of LV stroke volume and LV end-diastolic volume/mass ratio, there was persistent significant increase in distal LVES three-dimensional radius/wall thickness ratio and LVESV index post-surgery. Conclusions Despite apparently preserved LVESD, MR patients demonstrate significant spherical mid to apical LVES remodeling that contributes to higher LVESV than predicted by standard geometry-based calculations. Decreased LV strain post-surgery suggests that a volumetric analysis of LV remodeling and function may be preferred to evaluate disease progression in isolated MR.

Response to Letter Regarding Article, “Magnetic Resonance Imaging With 3-Dimensional Analysis of Left Ventricular Remodeling in Isolated Mitral Regurgitation: Implications Beyond Dimensions”

“…1 As pointed out, we demonstrated the Bullet formula underestimates left ventricular end-systolic volume, and further analysis does indeed demonstrate the mean Bullet formula-calculated left ventricular ejection fraction is significantly higher than left ventricular ejection fraction measured by magnetic resonance imaging (67%±9% versus 61%±7%, P<0.0001). Referral echocardiograms in our study used a visual estimate of left ventricular ejection fraction.…”

Left Ventricular Torsion Shear Angle Volume Approach for Non-Invasive Evaluation of Diastolic Dysfunction in Preserved Ejection Fraction

“…15,16 LVED stress was calculated as previously described. Two-dimensional (2D) strain at each timeframe and rates were measured using harmonic phase analysis.…”

Management of Asymptomatic Severe Degenerative Mitral Regurgitation

“…LV end-systolic volume obtained either from 3D echocardiography or cardiac magnetic resonance imaging (MRI) can better estimate the extent of LV remodeling. 12,13 LV ejection index The LV ejection index is an indexed product of LVESD/LV outflow tract velocity time integral. It reflects changes in LV cavity as a result of remodeling and LV systolic function.…”