Abstract (250 words max, 243 currently)
Background: Mitral Regurgitation (MR) can cause left ventricular dilation (remodeling). Reverse remodeling describes improved volumes after intervention. Reverse remodeling carries favorable prognoses, but not all MitraClip patients undergo reverse remodeling. We hypothesized pre-procedural global longitudinal strain (pre-GLS) will predict reverse remodeling one-year post MitraClip in all-cause MR patients.
Materials and Methods: Of the 189 MitraClips performed at our institution between 2007-2019, 57 patients had complete echocardiographic data,. Echocardiograms 0-120 days prior to and 6-24 months after procedure were retrospectively reviewed. Reverse remodeling was defined as reduction in end diastolic volume (EDV).
Results: In 20 sample echocardiograms, intra and inter-reader GLS variability was r=0.95 and r=0.90, respectively. Our population consisted of 55.2% female, 12.3% functional , 61.4% degenerative and 26.3% mixed mitral regurgitation. A reduction in EDV was demonstrated in 38 patients (67%). EDV, ESV, LAVi, and RVSP significantly decreased post-clip (all p<0.01) but not LVEF. Regression models showed pre-EDV (p<0.01) and pre-ESV (p<0.01) had significant crude and adjusted linear associations and │pre-GLS│ had a significant crude curvilinear association (linear p=0.04, quadratic p =0.04) with EDV reductions post clip. The curvilinear association showed among lower, more abnormal │pre-GLS│ values, higher │pre-GLS│ was associated with greater reductions in EDV. When adjusted for pre-EDV and pre-ESV, GLS lost significance(linear p=0.29, quadratic p=0.29).
Conclusion: Our study shows a majority of MitraClip patients demonstrate reverse remodeling and pre-GLS to be associated with reverse remodeling, though not robustly. Further study with large sample sizes can better define the association.
Keywords: MitraClip, Reverse remodeling, Global longitudinal strain, Mitral regurgitation, echocardiography, end diastolic volume
Introduction:Mitral Regurgitation(MR), which is found in 9.3% of people over age 75 years,1 independently worsens prognosis.2 MR can be clasified as primary or degenerative(DMR), when there is a structural abnormality of the mitral valve(MV); as secondary or functional(FMR), when the MR is due to left atrial or left ventricular(LV) dysfunction; or as mixed(MMR),when there is a combination of both.1, 3 LV dysfunction and remodeling leads to papillary muscle displacement, leaflet tethering and dilation of the mitral anulus, all impairing valve closure.1, 3 MR creates a volume overload state, promoting LV dilation. A detrimental remodeling cycle develops in which further LV dilation worsens MR, which worsens LV dilation and onward.4 Therapeutic interventions reducing MR can lessen LV volume overload, breaking the remodeling cycle. This allows for reverse remodeling, the normalization of the dilated volume dimensions.5 Post-surgical MR patients demonstrate more favorable prognoses when improvements in LV size and function are detected.4 The absence of reverse remodeling post MitraClip has been shown to correlate with recurrence of MR and symptom progression.6
Through a percutaneous femoral venous trans-septal approach, the MitraClip (Abbott Vascular) reduces MR by coapting the mitral leaflets7, and narrowing the MV annulus.8 In the EVEREST trials, the Mitraclip reduced the severity and mortality in MR patients.7, 9 More recently, the COAPT trial in 2018 showed moderate-severe MR patients with HFref demonstrated a 32.1 % absolute reduction in heart failure hospitalizations at 2 years and 16% absolute reduction in all cause death with a number needed to treat of six.10 In other studies, the Mitraclip has been shown to induce long term reverse remodeling, as evident by reduced end diastolic diameter(EDD) and index(EDI), reduced end systolic diameter(ESD) and index(ESI), and improved LV ejection fraction (EF).4, 11-13
Not all MitraClip patients experience reverse remodeling and the associated improved outcomes. In one study, only 77.3% demonstrated reverse remodeling, defined as at least 10% reduction in end diastolic volume (EDV).4 Predicting patients likely to experience reverse remodeling from MitraClips can aid clinical decision making regarding intervention candidacy.14
Known predictors of reverse modeling include: ischemic etiology, shorter pre-procedure duration of congestive heart failure,6pre-operative LV EDD and ESD5, and longitudinal strain15. Recently, global longitudinal strain(GLS) in a small sample of FMR patients demonstrated predictability for reductions in ESV.16 However, no study yet has evaluated reverse remodeling, in terms of EDV change, after MitraClip procedure in all types of MR patients predicted by global longitudinal strain(GLS).
GLS is a speckle echocardiographic parameter describing the change in length (deformation) of the entire myocardial LV wall.17 GLS is more reproducible than EF, is unaffected by tethering effects and is not reliant on geometric assumptions like EF.18, 19 Clinically, GLS has been shown to accurately identify early heart failure and subclinical LV dysfunction.14, 18-23 Also, it has been recognized as the best echocardiographic predictor of mortality.24Impaired preoperative GLS has demonstrated the ability to predict post-operative LV dysfunction among MR patients,14, 21, 25, 26 and even demonstrated the strongest correlation when compared to other known prognostic markers such as LVEF, atrial fibrillation, and LVESD.25
Our primary objective was to evaluate if preprocedural GLS(Pre-GLS) predicts LV reverse remodeling at one year, defined by 10% reduction in EDV, in moderate-severe and severe MR patients undergoing MitraClip procedure for all types of MR. As secondary objectives, we compared pre and post clip echocardiographic parameters and evaluated for GLS predictability differences between DMR and FMR subgroups.