Global longitudinal strain to determine optimal timing for surgery in primary mitral regurgitation: A systematic review

Persistent Shift in Laminar Planes Contribute to Post-Surgical Decline in LVEF in Patients with Primary Mitral Regurgitation

Background

The double helical direction of LV laminar sheets from endocardium to epicardium allows for wringing motion or LV twist. This provides a major component to LV wall thickening, stroke volume, and ejection fraction (EF). When this laminar sheet arrangement changes in Primary Mitral Regurgitation (PMR) and whether it reverts to normal after mitral valve repair is unknown.

Methods

Normal subjects (n=55) PMR patients had cardiac magnetic resonance imaging (CMR) with tissue tagging and 3-dimensional (3-D) analysis. They were grouped as asymptomatic moderate (n=23) and severe PMR (n=25) by regurgitant volume (RV) and pre-surgery (n=54) with post-surgery follow up at six, 12, and 24 months. Amplitude and directional vector of longitudinal (Ell), circumferential (Ecc), and maximal shortening were computed along with principle strain angles (Ecc°, Ell°, and Err°) at basal, mid, and distal LV levels.

Results

Asymptomatic moderate (RV 35 ± 16 ml; LVEF 62 ± 6%) and severe (RV 55 ±16 ml; LVEF 63 ± 6%) and symptomatic pre-surgery (RV 61 ± 29 ml; LVEF 63 ± 8%) had similar increases in mid LV 3-D radius to wall thickness (R/T), decrease in LV mass to volume (M/V) and sphericity index (SI) vs. normal. Radial longitudinal shear strain and mid LV Ecc° and EII° angles increased in all PMR groups, consistent with a shift in LV laminar plane direction and decreased LV SI. Post-surgery, LV end-diastolic (ED) volume, LVED M/V and 3-D R/T returned to normal within two years; however, mid LV circumferential, longitudinal, and maximal shortening decrease below normal. LV Ecc° and Ell° angles, and SI are unchanged from pre-surgery. LVEF decreased post-surgery and had a negative correlation with LV twist at six (r 2 = 0.30, p < 0.001), 12, (r 2 = 0.33, p < 0.001) and 24 months (r 2 = 0.38, p < 0.001) post-surgery.

Conclusion

Early changes in Ecc° and Ell° angles, radial longitudinal shear strain, and LV spherical dilatation are consistent with a shift of LV laminar planes that persists after surgery. The extent to which this affects LV twist may underlie a heretofore explanation underlying the decrease in LVEF after surgery for PMR.

Implications of myocardial strain in primary mitral regurgitation-a cardiovascular magnetic resonance study

AIMS

Chronic primary mitral regurgitation (MR) results in progressive left ventricular (LV) remodelling. Abnormal myocardial deformation (strain) can be present despite preserved ejection fraction (EF). Cardiovascular magnetic resonance (CMR) feature-tracking techniques allow assessment of global longitudinal strain (GLS) from routine cine images. The aim of this study is to evaluate the prognostic value of CMR feature tracking-derived GLS in patients with primary MR.

METHODS AND RESULTS

Consecutive patients undergoing CMR for chronic MR from January 2012 to June 2018 were enrolled. Patients with LVEF <50% were excluded. The composite primary outcome aiming to detect decompensation related to MR comprised (i) referral for mitral surgery owing to symptoms or LV systolic dysfunction or (ii) cardiovascular death. The secondary outcome was all-cause death. A total of 422 patients were followed for a median of 2.7 years, and the primary endpoint was met in 93 patients (34 patients reported symptoms at baseline). At multivariable analysis, GLS≥ -16.6% was associated with primary outcome [hazard ratio (HR) 1.90, P = 0.01]. In moderate MR cohort, patients with GLS≥ -16.6% had worse event-free survival, whereas there was no significant difference in mild or severe MR groups. GLS≥ -16.0% remained associated with all-cause death after adjusting for other covariates including the MR severity (HR 2.24, P = 0.02).

CONCLUSION

In patients with primary MR with preserved systolic function, GLS was associated with our composite outcomes and all-cause death. GLS may serve as a marker of cardiac dysfunction in the patients with primary MR with preserved systolic function allowing identification of patients likely to decompensate during observation.

Left Ventricular and Atrial Function Analysis Following Transcatheter Edge-to-Edge Mitral Valve Repair

Background: Conventional echocardiography used to assess volumes of the left ventricle (LV) and left atrium (LA) along with mitral regurgitation grade is routine in studies before and after transcatheter edge-to-edge mitral valve repair (Mitral TEER). Previous studies focus on LV parameter changes and comparison of the functions before and a few months following Mitral TEER implantation, as well as LA reverse remodeling, by assessing LV volumes. However, less is known regarding LA strain changes in the early phase after the procedure. The objective of the study was to assess the effect of Mitral TEER on LA strain early after TEER procedure. Methods: The retrospective study included 44 patients who underwent Mitral TEER. LA strain and volumes were evaluated by speckle tracking echocardiography at the baseline and 24-48 h following the procedure. Demographic, echocardiographic, and clinical characteristics were obtained and statistically analyzed. Results: LA global longitudinal strain (GLS) reservoir improved significantly (from 12.2 ± 7 to 14.7 ± 6.4, p = 0.0079) after Mitral TEER. Significant improvements were also seen in LA volumes (LA maximal and minimal volume), which reduced by 17% and 22.5% respectively. LV GLS was significantly changed (from -9.8% to -12.8%, p < 0.0001) following Mitral TEER, whereas LV stroke volume was not significantly different between the baseline and post-Mitral TEER (p = 0.7798). Conclusions: After successful Mitral TEER, there was a very early improvement in LA function. Two-dimensional speckle tracking echocardiography may contribute to our understanding of LA functional changes immediately post-procedure.

Primary mitral regurgitation: Toward a better quantification on left ventricular consequences

BACKGROUND

Left ventricular end-systolic diameter (LVESD) and ejection fraction (LVEF) are the parameters to look for when discussing repair in asymptomatic patients with a primary mitral regurgitation (PMR). Loading conditions are altering LV-function quantification. LV-myocardial work (LVMW) is a method based on pressure-strain loops.

HYPOTHESIS

We sought to evaluate the additive value of the LVMW for predicting clinical events in patients with PMR.

METHODS

103 patients (66% men, median age 57 years) with asymptomatic severe PMR were explored at rest and during an exercise stress echocardiography. LV myocardial global work index (GWI), constructive work (GCW), wasted work (GWW), and work efficiency (GWE) were measured with speckle-tracking echocardiography at rest and low workload. The indication for surgery was based on the heart teams' decision. The median follow-up was 670 days.

RESULTS

Clinical events occurred for 50 patients (48.5%) with a median of event-free survival distribution of 289 days. Systolic pulmonary artery pressure (sPAP) at rest was 32.61 ± 8.56 mmHg and did not predict the risk of event like LVEF and LVESD. Changes in, GLS (hazard ratio [HR] 0.55; 95% confidence interval (Cl): 0.36-0.83; p = .005), GWI (HR 1.01; 95% Cl: 1.00-1.02; p = .002) and GCW (HR 1.85; 95% Cl: 1.28-2.68; p = .001) in addition to Left Atrial Volume Index (HR 1.73; 95% CI: 1.28 - 2.33; p < 0,001) were independent predictors of events.

CONCLUSION

Changes in myocardial work indices related to low-dose exercise are relevant to best predict PMR patient prognosis It might help to better select patient's candidate for "early-surgery."

Sex Differences in Epidemiology, Morphology, Mechanisms, and Treatment of Mitral Valve Regurgitation

Sex-related disparities have been recognized in incidence, pathological findings, pathophysiological mechanisms, and diagnostic pathways of non-rheumatic mitral regurgitation. Furthermore, access to treatments and outcomes for surgical and interventional therapies among women and men appears to be different. Despite this, current European and US guidelines have identified common diagnostic and therapeutic pathways that do not consider patient sex in decision-making. The aim of this review is to summarize the current evidence on sex-related differences in non-rheumatic mitral regurgitation, particularly regarding incidence, imaging modalities, surgical-derived evidence, and outcomes of transcatheter edge-to-edge repair, with the goal of informing clinicians about sex-specific challenges to consider when making treatment decisions for patients with mitral regurgitation.