Reverse Left Ventricular Remodeling after Surgery in Primary Mitral Regurgitation: A Volume-Related Phased Process

1-Year Outcomes With Fourth-Generation Mitral Valve Transcatheter Edge-to-Edge Repair From the EXPAND G4 Study

BACKGROUND

The fourth-generation mitral transcatheter edge-to-edge repair (M-TEER) device introduced an improved clip deployment sequence, independent leaflet grasping, and 2 wider clip sizes to tailor the treatment of patients with mitral regurgitation (MR) for a broad range of anatomies. The 30-day safety and effectiveness of the fourth-generation M-TEER device were previously demonstrated.

OBJECTIVES

The aim of this study was to evaluate 1-year outcomes in a contemporary, real-world cohort of subjects treated with the MitraClip G4 system.

METHODS

EXPAND G4 is an ongoing prospective, multicenter, international, single-arm study that enrolled subjects with primary and secondary MR. One-year outcomes included MR severity (echocardiographic core laboratory assessed), heart failure hospitalization, all-cause mortality, functional capacity (NYHA functional class), and quality of life (Kansas City Cardiomyopathy Questionnaire).

RESULTS

A total of 1,164 subjects underwent M-TEER from 2020 to 2022. At 1 year, there was a durable reduction in MR to mild or less in 92.6% and to none or trace in 44.2% (P < 0.0001 vs baseline). Few subjects had major adverse events through 1 year (<2% for myocardial infarction, surgical reintervention, or single-leaflet device attachment). The 1-year Kaplan-Meier estimates for all-cause mortality and heart failure hospitalization were 12.3% and 16.9%. Significant improvements in functional capacity (NYHA functional class I or II in 82%; P < 0.0001 vs baseline) and quality of life (18.5-point Kansas City Cardiomyopathy Questionnaire overall summary score improvement; P < 0.0001) were observed.

CONCLUSIONS

M-TEER with the fourth-generation M-TEER device was safe and effective at 1 year, with durable reductions in MR severity to ≤1+ in more than 90% of patients and concomitant improvements in functional status and quality of life.

Neochordae implantation versus leaflet resection in mitral valve posterior leaflet prolapse and dilated left ventricle: a propensity score matching comparison with long-term follow-up

OBJECTIVES

Uncorrected severe mitral regurgitation (MR) due to posterior prolapse leads to left ventricular dilatation. At this stage, mitral valve repair becomes mandatory to avoid permanent myocardial injury. However, which technique among neochoardae implantation and leaflet resection provides the best results in this scenario remains unknown.

METHODS

We selected 332 patients with left ventricular dilatation and severe degenerative MR due to posterior leaflet (PL) prolapse who underwent neochoardae implantation (85 patients) or PL resection (247 patients) at our institution between 2008 and 2020. A propensity score matching analysis was carried on to decrease the differences at baseline.

RESULTS

Matching yielded 85 neochordae implantations and 85 PL resections. At 10 years, freedom from cardiac death and freedom from mitral valve reoperation were 92.6 ± 6.1% vs 97.8 ± 2.1% and 97.7 ± 2.2% vs 95 ± 3% in the neochordae group and in the PL resection group, respectively. The MR ≥2+ recurrence rate was 23.9 ± 10% in the neochordae group and 20.8 ± 5.8% in the PL resection group (P = 0.834) at 10 years. At the last follow-up, the neochordae group showed a higher reduction of left ventricular end-diastolic diameter (44 vs 48 mm; P = 0.001) and a better ejection fraction (60% vs 55%; P < 0.001) compared to PL resection group.

CONCLUSIONS

In this subgroup of patients, both neochordae implantation and leaflet resection provide excellent durability of the repair in the long term. Neochordae implantation might have a better effect on dilated left ventricle.

Stage-based approach to predict left ventricular reverse remodeling after mitral repair

Background

Although predictors of reverse left ventricular (LV) remodeling postmitral valve repair are critical for guiding perioperative decision‐making, there remains a paucity of randomized, prospective data to support the criteria that potential predictor variables must meet.

Methods and Results

The CAMRA CardioLink‐2 randomized trial allocated 104 patients to either leaflet resection or preservation strategies for mitral repair. The correlation of indexed left ventricular end‐systolic volume (LVESVI), indexed left ventricular end‐diastolic volume (LVEDVI), and left ventricular ejection fraction (LVEF) were tested with univariate analysis and subsequently with multivariate analysis to determine independent predictors of reverse remodeling at discharge and at 12 months postoperatively. At discharge, both LVESVI and LVEDVI were independently associated with their preoperative values (p < .001 for both) and LVEF by preoperative LVESVI (p < .001). Mitral ring size was favorably associated with the change in LVESVI (p < .05) and LVEF (p < .01) from predischarge to 12 months, while the mean mitral valve gradient after repair was adversely associated with the change in LVESVI (p < .05) and LVEDVI (p < .05). No significant associations were found between reverse remodeling and coaptation height nor mitral repair technique.

Conclusions

Beyond confirming the lack of impact of mitral repair technique on reverse remodeling, this investigation suggests that recommending surgery before significant LV dilatation or dysfunction, as well as higher postoperative mitral valve hemodynamic performance, may enhance remodeling capacity following mitral repair.

Left Ventricular Remodeling in Non-syndromic Mitral Valve Prolapse: Volume Overload or Concomitant Cardiomyopathy?

Mitral valve prolapse (MVP) is a common valvular disorder that can be associated with mitral regurgitation (MR), heart failure, ventricular arrhythmias and sudden cardiac death. Given the prognostic impact of these conditions, it is important to evaluate not only mitral valve morphology and regurgitation, but also the presence of left ventricular (LV) function and remodeling. To date, several possible hypotheses have been proposed regarding the underlying mechanisms of LV remodeling in the context of non-syndromic MVP, but the exact pathophysiological explanation remains elusive. Overall, volume overload related to severe MR is considered the main cause of LV dilatation in MVP. However, significant LV remodeling has been observed in patients with MVP and no/mild MR, particularly in patients with bileaflet MVP or Barlow’s disease, generating several new hypotheses. Recently, the concept of “prolapse volume” was introduced, adding a significant volume load to the LV on top of the transvalvular MR volume. Another possible hypothesis is the existence of a concomitant cardiomyopathy, supported by the link between MVP and myocardial fibrosis. The origin of this cardiomyopathy could be either genetic, a second hit (e.g., on top of genetic predisposition) and/or frequent ventricular ectopic beats. This review provides an overview of the different mechanisms and remaining questions regarding LV remodeling in non-syndromic MVP. Since technical specifications of imaging modalities impact the evaluation of MR severity and LV remodeling, and therefore might influence clinical decision making in these patients, this review will also discuss assessment of MVP using different imaging modalities.

Mitral repair with leaflet preservation versus leaflet resection and ventricular reverse remodeling from a randomized trial

OBJECTIVES

In the Canadian Mitral Research Alliance (CAMRA) Trial CardioLink-2 leaflet resection versus preservation techniques for posterior leaflet prolapse was investigated and no difference was shown in their effect on mean mitral gradient at peak exercise at 12 months postoperatively. The purpose of this subanalysis was to evaluate the effect of the 2 strategies on left ventricular (LV) reverse remodeling after repair.

METHODS

A total of 104 patients were randomized to either a leaflet resection or leaflet preservation strategy. Echocardiograms, performed at baseline (preoperative), predischarge, and 12 months postoperatively, were analyzed in a blinded fashion at a core laboratory.

RESULTS

All patients underwent successful mitral repair. At discharge, 3 patients showed moderate mitral regurgitation, whereas the remainder showed mild or less regurgitation. Compared with the baseline echocardiogram, the indexed end diastolic volume was reduced at the discharge echocardiogram (P < .0001) and was further reduced at the 12-month echocardiogram (P = .01). In contrast, the indexed end systolic volume did not significantly change from baseline assessed at the predischarge echocardiogram (P = .32) but improved at 12 months postoperatively (P < .0001), resulting in a corresponding improvement in ejection fraction at 12 months (P < .0001). The type of mitral repair strategy had no significant effect on LV reverse remodeling trends.

CONCLUSIONS

The mitral repair strategies used did not influence postoperative LV reverse remodeling, which occurred in stages. Although LV end diastolic dimensions recovered before discharge, improvements in LV end systolic dimension were evident 12 months after repair.

Replacement Myocardial Fibrosis in Patients With Mitral Valve Prolapse: Relation to Mitral Regurgitation, Ventricular Remodeling, and Arrhythmia

BACKGROUND

Mitral valve prolapse (MVP) is a frequent disease that can be complicated by mitral regurgitation (MR), heart failure, arterial embolism, rhythm disorders, and death. Left ventricular (LV) replacement myocardial fibrosis, a marker of maladaptive remodeling, has been described in patients with MVP, but the implications of this finding remain scarcely explored. We aimed at assessing the prevalence, pathophysiological and prognostic significance of LV replacement myocardial fibrosis through late gadolinium enhancement (LGE) by cardiac magnetic resonance in patients with MVP.

METHODS

Four hundred patients (53±15 years of age, 55% male) with MVP (trace to severe MR by echocardiography) from 2 centers, who underwent a comprehensive echocardiography and LGE cardiac magnetic resonance, were included. Correlates of replacement myocardial fibrosis (LGE+), influence of MR degree, and ventricular arrhythmia were assessed. The primary outcome was a composite of cardiovascular events (cardiac death, heart failure, new-onset atrial fibrillation, arterial embolism, and life-threatening ventricular arrhythmia).

RESULTS

Replacement myocardial fibrosis (LGE+) was observed in 110 patients (28%; 91 with myocardial wall including 71 with basal inferolateral wall, 29 with papillary muscle). LGE+ prevalence was 13% in trace-mild MR, 28% in moderate MR, and 37% in severe MR, and was associated with specific features of mitral valve apparatus, more dilated LV and more frequent ventricular arrhythmias (45% versus 26%, P<0.0001). In trace-mild MR, despite the absence of significant volume overload, abnormal LV dilatation was observed in 16% of patients and ventricular arrhythmia in 25%. Correlates of LGE+ in multivariable analysis were LV mass (odds ratio, 1.01 [95% CI, 1.002-1.017], P=0.009) and moderate-severe MR (odds ratio, 2.28 [95% CI, 1.21-4.31], P=0.011). LGE+ was associated with worse 4-year cardiovascular event-free survival (49.6±11.7 in LGE+ versus 73.3±6.5% in LGE-, P<0.0001). In a stepwise multivariable Cox model, MR volume and LGE+ (hazard ratio, 2.6 [1.4-4.9], P=0.002) were associated with poor outcome.

CONCLUSIONS

LV replacement myocardial fibrosis is frequent in patients with MVP; is associated with mitral valve apparatus alteration, more dilated LV, MR grade, and ventricular arrhythmia; and is independently associated with cardiovascular events. These findings suggest an MVP-related myocardial disease. Last, cardiac magnetic resonance provides additional information to echocardiography in MVP.