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.