Predictors of Left Ventricular Dysfunction After Surgery for Degenerative Mitral Regurgitation

Presentation and outcomes of women and men undergoing surgery for degenerative mitral regurgitation

OBJECTIVES

Degenerative mitral regurgitation is associated with heart failure, arrhythmia and mortality. The impact of sex on timing of surgical referral and outcomes has not been reported comprehensively. We examined preoperative status and surgical outcomes of male versus female degenerative mitral valve regurgitation patients undergoing surgery.

METHODS

We reviewed our institutional database for all patients undergoing surgery for degenerative mitral regurgitation between 2013 and 2021. Preoperative clinical and echocardiographic variables, surgical characteristics and outcomes were compared, and left atrial strain in available images.

RESULTS

Of 963 patients, 314 (32.6%) were female. Women were older (67 vs 64 years, P = 0.031) and more often had bileaflet prolapse (19.4% vs 13.8%, P = 0.028), mitral annular calcification (12.1% vs 5.4%, P < 0.001) and tricuspid regurgitation (TR; 31.8% vs 22.5%, P = 0.001). Indexed left ventricular end-diastolic and end-systolic diameters were higher in women, with 29.4 vs 26.7 mm/m2 (P < 0.001) and 18.2 vs 17 mm/m2 (P < 0.001), respectively, and left atrial conduit strain lower (17.6% vs, 21.2%, P = 0.001). Predicted risk of mortality was 0.73% vs 0.54% in men (P = 0.023). Women required mechanical circulatory support more frequently (1.3% vs 0%, P = 0.011), had longer intensive care unit stay (29 vs 26 h, P < 0.001), mechanical ventilation (5.4 vs 5 h, P = 0.036), and overall hospitalization (7 vs 6 days, P < 0.001). There was no difference in long-term reoperation-free survival (P = 0.35).

CONCLUSIONS

Women undergoing mitral valve repair are older and show indicators of more advanced disease with long-standing left ventricular impairment. Guidelines may need to be adjusted and address this disparity, to improve postoperative recovery times and outcomes.

Moving from left ventricular ejection fraction to deformation imaging in mitral valve regurgitation

The increasing prevalence of valvular heart diseases, specifically mitral regurgitation (MR), underscores the need for a careful and timely approach to intervention. Severe MR, whether primary or secondary, when left untreated leads to adverse outcomes, emphasizing the critical role of a timely surgical or transcatheter intervention. While left ventricular ejection fraction (LVEF) remains the guideline-recommended measure for assessing left ventricle damage, emerging evidence raises concerns regarding its reliability in MR due to its volume-dependent nature. This review summarizes the existing literature on the role of LVEF and deformation imaging techniques, emphasizing the latter's potential in providing a more accurate evaluation of intrinsic myocardial function. Moreover, it advocates the need for an integrated approach that combines traditional with emerging measures, aiming to optimize the management of patients with MR. It attempts to highlight the need for future research to validate the clinical application of deformation imaging techniques through large-scale studies.

Timing of Surgery for Asymptomatic Primary Mitral Regurgitation: Possible Value of Early, Serial Measurements of Left Ventricular Sphericity

Asymptomatic primary mitral regurgitation due to myxomatous degeneration of the mitral valve leaflets may remain so for long periods, even as left ventricular function progresses to a decompensated stage. During the early compensated stage, the ventricle's initial response to the volume overload is an asymmetric increase in the diastolic short axis dimension, accomplished by a diastolic shift of the interventricular septum into the right ventricular cavity, creating a more spherical left ventricular diastolic shape, increasing diastolic filling and stroke volume. Early valve repair is recommended to reduce postoperative left ventricular dysfunction. Early serial measurements of left ventricular sphericity index [LV-Si]. during the compensated stage of mitral regurgitation might identify subtle changes in left ventricular shape and assist in determining the optimal earliest timing for surgical intervention.

Propensity Matched Outcomes of Minimally Invasive Mitral Surgery: Does a Heart-Team Approach Eliminate Female Gender as an Independent Risk Factor?

BACKGROUND

There is increasing evidence that female gender is an independent risk factor for cardiac surgery. Minimally invasive mitral surgery (MIV) has proven to have excellent long-term results, but little is known about gender-dependent outcomes. The aim of our study was to analyze our heart team's decision-based MIV-specialized cohort.

METHODS

In-hospital and follow-up data were retrospectively collected. The cohort was divided into gender groups and propensity-matched groups.

RESULTS

Between 22 July 2013 and 31 December 2022, 302 consecutive patients underwent MIV. Before matching, the total cohort showed that women were older, had a higher EuroSCORE II, were more symptomatic, and had more complex valve pathology and tricuspid regurgitation resulting in more valve replacements and tricuspid repairs. Intensive and hospital stays were longer. In-hospital deaths (n = 3, all women) were comparable, with more atrial fibrillation in women. The median follow-up time was 3.44 (0.008-8.9) years. The ejection fraction, NYHA, and recurrent regurgitation were low and comparable and atrial fibrillation more frequent in women. The calculated 5-year survival and freedom from re-intervention were comparable (p = 0.9 and p = 0.2). Propensity matching compared 101 well-balanced pairs; women still had fewer resections and more atrial fibrillation. During the follow-up, women had a better ejection fraction. The calculated 5-year survival and freedom from re-intervention were comparable (p = 0.3 and p = 0.3).

CONCLUSIONS

Despite women being older and sicker, with more complex valve pathology and subsequent replacement, early and mid-term mortality and the need for reoperation were low and comparable before and after propensity matching, which might be the result of the MIV setting combined with our patient-tailored decision-making. We believe that a multidisciplinary heart team approach is crucial to optimize patient outcomes in MIV, and it might also reduce the widely reported increased surgical risk in female patients. Further studies are needed to prove our findings.

Prognostic value of left ventricular global longitudinal strain in mitral regurgitation: a systematic review

Conventional echocardiographic assessment may overestimate the left ventricular (LV) function in mitral regurgitation (MR). LV global longitudinal strain (GLS) is more sensitive marker to detect subclinical LV dysfunction. Multiple studies have investigated the prognostic value of LV-GLS in MR to examine its potential to determine the timing and indication of intervention. This systematic review aimed to assess the prognostic value of LV-GLS in patients with mitral regurgitation (MR) to define its clinical applicability. PUBMED and EMBASE were queried through July 2021 to identify studies investigating the prognostic value of LV-GLS in MR. A total of 24 observational studies with 5267 patients were identified. Sixteen studies investigated for primary MR, 7 studies for secondary MR, and 1 study for both. Most studies included patients who underwent intervention. There was significant heterogeneity in patient population, intervention status, follow-up period, LV-GLS cutoff value, outcomes, and statistical methods among the studies. Meta-analysis was not performed considering the significant variability. With exception to 1 study, all studies demonstrated significant association between impaired LV-GLS and worse clinical and echocardiographic outcomes in primary MR. Prognostic value of LV-GLS in secondary MR was less certain due to inconsistent findings and limited reporting. LV-GLS is a promising parameter of prognostication in primary MR and can be considered as alternative to determine the timing of intervention. However, the optimal cutoff value remains unclear. The prognostic value of LV-GLS in secondary MR is less clear. Further large-scale prospective study is warranted before its routine clinical application.

Interstitial Collagen Loss, Myocardial Remodeling, and Function in Primary Mitral Regurgitation

Interstitial collagen loss and cardiomyocyte ultrastructural damage accounts for left ventricular (LV) sphericity and decrease in LV twist and circumferential strain. Normal LV diastolic function belies significantly abnormal left atrial (LA) function and early LV diastolic untwist rate. This underscores the complex interplay of LV and LA myocardial remodeling and function in the pathophysiology of primary mitral regurgitation. In this study, we connect LA function with LV systolic and diastolic myocardial remodeling and function using cardiac magnetic resonance tissue tagging in primary mitral regurgitation.

Propensity Score-Matched Comparison of Right Ventricular Strain in Women and Men Before and After Left Ventricular Assist Device Implantation

Objective: Adverse events following left ventricular assist device (LVAD) implantation are more common in women than in men, but the impact of gender differences on right ventricular (RV) failure is not well defined. Therefore, we calculated RV strain before and after LVAD implantation in matched groups of men and women to determine if gender differences in RV failure after LVAD might account for the gender differences in overall outcomes. Methods: RV free wall longitudinal strain (FWS) and fractional area change were calculated preoperatively and 3 months postoperatively using speckle-tracking echocardiography analysis. A total of 172 patients (86 women, 86 men) were then propensity score matched (1:1) for comparison. Results: Although women had higher preoperative CHA₂DS₂-VASc scores and more frequent moderate mitral regurgitation than men (P = 0.018), the preoperative hemodynamic parameters were similar. Preoperative RV-FWS was -6.7% in women and -6.0% in men (P = 0.65). Postoperatively, women had more progression to severe tricuspid regurgitation (TR) than men (15% vs 7%, P = 0.06). At 3 months the RV-FWS was -7.7% in women and -7.0% in men (P = 0.59). Postoperative TR was moderate-severe in 20% of women and in 9% of men (P = 0.001). Women had a higher incidence of venous thromboembolism, cardiac arrhythmias, and bleeding compared with men. Women also had higher mortality rates at discharge and 30 days after surgery, but the survival rates at 5 years were similar. Conclusions: RV strain measurements track standard hemodynamic and echocardiographic parameters and confirm that gender differences in outcomes following LVAD implantation are not related to gender differences in RV failure rates.

Prognostic Implications of Left Ventricular Global Longitudinal Strain in Patients With Surgically Treated Mitral Valve Disease and Preserved Ejection Fraction

Background

This study investigated whether left ventricular (LV) global longitudinal strain (LV-GLS), as an LV function parameter less affected by mitral valve (MV) repair or prosthesis, is associated with clinical outcomes in patients with surgically treated MV disease.

Methods

Among 750 patients who underwent MV surgery, we assessed LV-GLS by speckle tracking echocardiography in 344 patients (148 men, mean age 58 ± 13 years) who showed preserved LV ejection fraction on echocardiography between 6 months and 2 years after MV surgery and who did not undergo aortic valve surgery. The assessed clinical events included admission for worsening of heart failure and cardiac death.

Results

During a period of 42.4 ± 26.0 months, 32 (9.3%) patients were hospitalized for worsening heart failure, and 3 (0.8%) died due to cardiac causes. The absolute value of LV-GLS (|LV-GLS|) was significantly lower in patients with clinical events than in those without (12.1 ± 3.1 vs. 15.0 ± 3.2%, p < 0.001) despite comparable LV ejection fraction between groups. |LV-GLS| showed predictive value for clinical events (cut-off 13.9%, area under the curve 0.744, p < 0.001). Patients with |LV-GLS| ≤14.0% had poorer outcomes than those with |LV-GLS| >14.0% (log-rank p < 0.001). Prognosis was worse in patients with |LV-GLS| ≤14.0% and pulmonary hypertension than among those who with |LV-GLS| ≤14.0% without pulmonary hypertension (log rank p < 0.001). In nested Cox proportional hazard regression models, reduced |LV-GLS| was independently associated with the occurrence of clinical events.

Conclusions

In patients with surgically treated MV and preserved LV ejection fraction, assessment of LV-GLS provides functional information associated with cardiovascular outcomes.

Does gender bias affect outcomes in mitral valve surgery for degenerative mitral regurgitation?

OBJECTIVES

This study was conducted to determine if gender bias explains the worse outcomes in women than in men who undergo mitral valve surgery for degenerative mitral regurgitation.

METHODS

Patients who underwent mitral valve surgery for degenerative mitral regurgitation with or without concomitant ablation surgery for atrial fibrillation were identified from the Cardiovascular Research Database of the Clinical Trial Unit of the Bluhm Cardiovascular Institute at Northwestern Memorial Hospital and were defined according to the Society of Thoracic Surgery National Adult Cardiac Surgery Database. Of the 1004 patients (33% female, mean age 62.1 ± 12.4 years; 67% male, mean age 60.1 ± 12.4 years) who met this criteria, propensity score matching was utilized to compare sex-related differences.

RESULTS

Propensity score matching of 540 patients (270 females, mean age 61.0 ± 12.2; 270 males, mean age 60.9 ± 12.3) demonstrated that 98% of mitral valve surgery performed in both groups was mitral valve repair and 2% was mitral valve replacement. Preoperative CHA2DS2-VASc scores were higher in women and fewer women were discharged directly to their homes. Before surgery, women had smaller left heart chambers, lower cardiac outputs, higher diastolic filling pressures and higher volume responsiveness than men. However, preoperative left ventricular and right ventricular strain values, which are normally higher in women, were similar in the 2 groups, indicating worse global strain in women prior to surgery.

CONCLUSIONS

The worse outcomes reported in women compared to men undergoing surgery for degenerative mitral regurgitation are misleading and not based on gender bias except in terms of referral patterns. Men and women who present with the same type and degree of mitral valve disease and similar comorbidities receive the same types of surgical procedures and experience similar postoperative outcomes. Speckle-tracking echocardiography to assess global longitudinal strain of the left and right ventricles should be utilized to monitor for myocardial dysfunction related to chronic mitral regurgitation.

Speckle tracking echocardiography in primary mitral regurgitation: should we reconsider the time for intervention?

Thanks to the improvement in mitral regurgitation (MR) diagnostic and therapeutic management, with the introduction of minimally invasive techniques which have considerably reduced the individual surgical risk, the optimization of the timing for MR “open” or percutaneous surgical treatment has become a main concern which has highly raised scientific interest. In fact, the current indications for intervention in MR, especially in asymptomatic patients, rely on echocardiographic criteria with high severity cut-offs that are fulfilled only when not only mitral valve apparatus but also the cardiac chambers’ structure and function are severely impaired, which results in poor benefits for post-operative clinical outcome. This led to the need of new indices to redefine the optimal surgical timing in these patients. Speckle tracking echocardiography provides early markers of cardiac dysfunction due to subtle myocardial impairment; therefore, it could offer pivotal information in this setting. In fact, left ventricular and left atrial strains have already shown evidence about their usefulness in recognizing MR impact not only on symptoms and quality of life but also on cardiovascular events and new-onset atrial fibrillation in these patients. Moreover, right ventricular strain could be used to identify those patients with advanced cardiac damage and different grades of right ventricular dysfunction, which entails higher risks for cardiac surgery that could overweigh surgical benefits. This review aims to describe the importance of reconsidering the timing of intervention in MR and to analyze the potential additive value of speckle tracking echocardiography in this clinical setting.

Timing of intervention in asymptomatic patients with valvular heart disease

Current management of valvular heart disease (VHD) seeks to optimize long-term outcome by timely intervention. Recommendations for treatment of patients with symptoms due to severe valvular disease are based on a foundation of solid evidence. However, when to intervene in asymptomatic patients remains controversial and decision requires careful individual weighing of the potential benefits against the risk of intervention and its long-term consequences. The primary rationale for earlier intervention is prevention of irreversible left ventricular (LV) myocardial changes that might result in later clinical symptoms and adverse cardiac events. A number of outcome predictors have been identified that facilitate decision-making. This review summarizes current recommendations and discusses recently published data that challenge them suggesting even earlier intervention. In adults with asymptomatic aortic stenosis (AS), emerging risk markers include very severe valve obstruction, elevated serum natriuretic peptide levels, and imaging evidence of myocardial fibrosis or increased extracellular myocardial volume. Currently, transcatheter aortic valve implantation (TAVI) is not recommended for treatment of asymptomatic severe AS although this may change in the future. In patients with aortic regurgitation (AR), the potential benefit of early intervention in preventing LV dilation and dysfunction must be balanced against the long-term risk of a prosthetic valve, a particular concern because severe AR often occurs in younger patients with a congenital bicuspid valve. In patients with mitral stenosis, the option of transcatheter mitral balloon valvotomy tilts the balance towards earlier intervention to prevent atrial fibrillation, embolic events, and pulmonary hypertension. When chronic severe mitral regurgitation is due to mitral valve prolapse, anatomic features consistent with a high likelihood of a successful and durable valve repair favour early intervention. The optimal timing of intervention in adults with VHD is a constantly changing threshold that depends not only on the severity of valve disease but also on the safety, efficacy, and long-term durability of our treatment options.

Surgical treatment of mitral regurgitation

PURPOSE OF REVIEW

Mitral repair is the best treatment for degenerative mitral regurgitation. Many patients are referred too late for optimal outcomes. The US repair vs. replacement rate is only 60-80%, at a time when the inferiority of replacement has been established. Therefore, widely used traditional techniques of repair are being reappraised.

RECENT FINDINGS

Identification of risk factors predictive of poor early and late outcome have improved timing for surgical referral. Composite risk scores have been developed. Novel echocardiographic, cardiac MRI, and molecular level risk factors could improve timing. Analysis of factors contributing to low repair rates is also of critical importance. The role of institutional and surgeon volumes have been identified. More detailed data on the importance of dynamic function of the mitral valve have led to improved repair techniques such as intraoperative simulation of end diastole and early systole, use of expanded polytetrafluoroethylene neochords instead of leaflet resection, and dynamic instead of rigid annuloplasty.

SUMMARY

Our perception of mitral regurgitation has changed from a seemingly simple condition to one of considerable complexity at multiple levels. National guidelines should be studied and followed.