Predictors of Mitral Valve Repair: Clinical and Surgeon Factors

Gender differences in outcomes following cardiac surgery: implications for managing patients with mitral valve disease

PURPOSE OF REVIEW

This review summarizes the differences in clinical outcomes following cardiac surgery according to gender.

RECENT FINDINGS

Women comprise a large proportion of patients presenting with coronary artery or valvular heart disease. Although it is well known that women have poorer survival following bypass surgery compared with men, more recent data confirm that women also have poorer outcomes after heart valve surgery. Women are also more likely to receive mitral valve replacement instead of repair, when compared with men. These divergent outcomes are because of many factors, including valve disease and clinical presentation, which may result in delayed surgical referral in women.

SUMMARY

Factors that result in poorer outcomes following heart valve surgery, including mitral valve surgery, between men and women remain incompletely understood. These may relate to differences in clinical presentation, valve morphology, and physiology. Further research is needed to clarify differences in heart valve outcomes according to gender.

Early and mid-term clinical outcome in younger and elderly patients undergoing mitral valve repair with or without tricuspid valve repair

OBJECTIVES

Data regarding durability and midterm benefits of mitral valve (MV) repair in elderly patients are scarce. To evaluate the feasibility and safety of MV repair in elderly patients, we performed a retrospective data analysis.

METHODS

We compared clinical outcomes in younger patients (<75 years: n = 462) and older patients (≥75 years: n = 100) undergoing MV repair with or without tricuspid valve (TV) repair. The primary end-point was 30-day mortality.

RESULTS

The preoperative risk profile (EuroSCORE, NYHA class, percentage pulmonary hypertension, percentage diabetes) was higher in older patients compared with younger patients. Nevertheless, operative complications such as low cardiac output syndrome, stroke, infections, the need of haemofiltration and IABP use did not differ significantly between the two groups. The thirty-day mortality rate was 0% in older patients and 1% in younger patients (P = 0.30). In the subgroup of patients with double valve repair, the 30-day mortality rate in older patients (n = 28) and younger patients (n = 46) was 0 and 4%, respectively (P = 0.27). In older and younger patients, the 6-month mortality rate was 4 and 2%, respectively (P = 0.16), and the 1-year mortality rate was 10 and 3%, respectively (P = 0.001). The propensity score-adjusted odds ratio of 1-year mortality with the group of younger patients as a reference was 2.04 (95% confidence interval: 0.77-5.40; P = 0.15) for older patients. Freedom from 1-year reoperation did not differ significantly between age groups.

CONCLUSIONS

Data demonstrate excellent postoperative mortality rates in older patients undergoing MV repair with or without TV repair. Consequently, even in older patients with numerous comorbidities, MV repair should be considered a suitable surgical method.

Three-dimensional ultrasound-derived physical mitral valve modeling

PURPOSE

Advances in mitral valve repair and adoption have been partly attributed to improvements in echocardiographic imaging technology. To educate and guide repair surgery further, we have developed a methodology for fast production of physical models of the valve using novel three-dimensional (3D) echocardiographic imaging software in combination with stereolithographic printing.

DESCRIPTION

Quantitative virtual mitral valve shape models were developed from 3D transesophageal echocardiographic images using software based on semiautomated image segmentation and continuous medial representation algorithms. These quantitative virtual shape models were then used as input to a commercially available stereolithographic printer to generate a physical model of the each valve at end systole and end diastole.

EVALUATION

Physical models of normal and diseased valves (ischemic mitral regurgitation and myxomatous degeneration) were constructed. There was good correspondence between the virtual shape models and physical models.

CONCLUSIONS

It was feasible to create a physical model of mitral valve geometry under normal, ischemic, and myxomatous valve conditions using 3D printing of 3D echocardiographic data. Printed valves have the potential to guide surgical therapy for mitral valve disease.

Preoperative risk factors of medium-term mitral valve repair outcome

OBJECTIVES

This study aimed to evaluate risk factors that affect mitral valve (MV) repair outcomes.

METHODS

From 2002 to 2012, 580 consecutive patients with mitral regurgitation (MR) underwent MV repair. Of the total number of patients, 48.9% were found to be in New York Heart Association (NYHA) Class III or IV. Anterior, posterior and bileaflet prolapse was present in 34.8, 47.6 and 17.6% of patients, respectively. Atrial fibrillation (AF) was found in 29.7% of patients. The mean follow-up was 5.3 ± 2.6 years.

RESULTS

There were eight early and 14 late deaths. NYHA Class III/IV, left ventricular ejection fraction ≤50%, systolic pulmonary artery pressure ≥50 mmHg, AF and low cardiac output syndrome with extracorporeal membrane oxygen were independent predictors of early mortality. AF, NYHA Class III/IV, left ventricular end-systolic diameter ≥40 mm and systolic pulmonary artery pressure ≥50 mmHg remained predictors of late mortality. At 5 years, the rate of survival, freedom from reoperation and recurrent moderate to severe MR was 99.0 ± 0.6 97.2 ± 0.8 and 93.3 ± 1.2%, respectively. Anterior leaflet involvement was predictive of reoperation and recurrent moderate to severe MR. In patients with a moderate tricuspid regurgitation (TR) and annulus <40 mm, the degree of TR during follow-up was worse with right ventricular dilatation.

CONCLUSIONS

MV repair should be performed before the deterioration of ventricular function, development of pulmonary hypertension and AF occurrence. The pathophysiology of MR affects MV repair durability, while concomitant tricuspid annuloplasty should be considered in patients with moderate TR despite annular dilatation.

Mitral valve repair in asymptomatic patients with severe mitral regurgitation: pushing past the tipping point

Degenerative mitral valve regurgitation (MR) is the one of the most frequent valvular heart conditions in the Western world and is increasingly recognized as an important preventable cause of chronic heart failure. This condition also represents the most common indication for mitral surgery and is of particular interest because the mitral valve can be repaired in most patients with very low surgical risk. Historical single-center studies have supported the performance of "early mitral valve repair" in asymptomatic patients with severe degenerative MR to normalize survival and improve late outcomes. Emerging recent evidence further indicates for the first time that the prompt surgical correction of severe MR due to flail mitral leaflets within 3 months following diagnosis in asymptomatic patients without classical Class I indications (symptoms or left ventricular dysfunction) conveys a 40% decrease in the risk of late death and a 60% diminution in heart failure incidence. A 10-point rationale based on the weight of rapidly accumulating clinical data, supports the performance of early mitral valve repair even in the absence of symptoms, left ventricular dysfunction, or guideline-based triggers; when effective operations can be provided using conventional or minimally invasive techniques at very low surgical risk.

Minimally invasive valve surgery

Cardiac valve surgery is life saving for many patients. The advent of minimally invasive surgical techniques has historically allowed for improvement in both postoperative convalescence and important clinical outcomes. The development of minimally invasive cardiac valve repair and replacement surgery over the past decade is poised to revolutionize the care of cardiac valve patients. Here, we present a review of the history and current trends in minimally invasive aortic and mitral valve repair and replacement, including the development of sutureless bioprosthetic valves.

The expanding role of mitral valve repair in triple valve operations: contemporary North American outcomes in 8,021 patients

BACKGROUND

Although the operative risk of multivalve operations has historically been high, current outcomes are poorly understood. We sought to evaluate factors influencing contemporary results of triple-valve operations using The Society of Thoracic Surgeons Adult Cardiac Surgery Database.

METHODS

Among patients undergoing combined mitral, aortic, and tricuspid valve (triple- valve) operations between 1993 and 2011, aortic valve repair patients were excluded and those having aortic valve replacement were analyzed according to whether they underwent repair vs replacement of the mitral valve (MV) and tricuspid valve (TV). Temporal trends in operative death and clinical outcomes were examined using unadjusted and adjusted analyses.

RESULTS

A total of 8,021 triple-valve patients were studied. The median (25th percentile, 75th percentile) age was 67 years (59, 77 years), 4,809 (60%) were women, 4,488 (56%) had New York Heart Association class III to IV symptoms, and the mean (25th percentile, 75th percentile) ejection fraction was 50% (40%, 60%). MV repair was performed in 2,728 (34%) patients overall and increased over time from 13% (1993 to 1997) to 41% (2008 to 2011). TV repair was performed in 7,512 (94%) patients overall and increased over time from 86% (1993 to 1997) to 96% (2008 to 2011). Unadjusted operative mortality decreased from 17% in 1993 to 9% in 2011. Adjusted odds ratios (95% confidence intervals) of operative mortality were lower in those having MV repair (0.72 [0.61 to 0.85]), TV repair (0.64 [0.50 to 0.83]), and MV+TV repair (0.46 [0.34 to 0.63]) compared with those having replacements. Unadjusted and adjusted odds of stroke were similar between groups and not significant for all.

CONCLUSIONS

This large series demonstrates that surgical results of triple-valve operations have continued to improve during the past 18 years. MV and TV repair were associated with improvements in early survival. Although further study is required to understand late outcomes, these data suggest that broader efforts to perform MV repair instead of replacement in this high-risk patient population appear warranted.

Measurement of mitral leaflet and annular geometry and stress after repair of posterior leaflet prolapse: virtual repair using a patient-specific finite element simulation

BACKGROUND

Recurrent mitral regurgitation after mitral valve (MV) repair for degenerative disease occurs at a rate of 2.6% per year and reoperation rate progressively reaches 20% at 19.5 years. We believe that MV repair durability is related to initial postoperative leaflet and annular geometry with subsequent leaflet remodeling due to stress. We tested the hypothesis that MV leaflet and annular stress is increased after MV repair.

METHODS

Magnetic resonance imaging was performed before and intraoperative three-dimensional (3D) transesophageal echocardiography was performed before and after repair of posterior leaflet prolapse in a single patient. The repair consisted of triangular resection and annuloplasty band placement. Images of the heart were manually co-registered. The left ventricle and MV were contoured, surfaced, and a 3D finite element (FE) model was created. Elements of the posterior leaflet region were removed to model leaflet resection and virtual sutures were used to repair the leaflet defect and attach the annuloplasty ring.

RESULTS

The principal findings of the current study are the following: (1) FE simulation of MV repair is able to accurately predict changes in MV geometry including changes in annular dimensions and leaflet coaptation; (2) average posterior leaflet stress is increased; and (3) average anterior leaflet and annular stress are reduced after triangular resection and mitral annuloplasty.

CONCLUSIONS

We successfully conducted virtual mitral valve prolapse repair using FE modeling methods. Future studies will examine the effects of leaflet resection type as well as annuloplasty ring size and shape.

Estimating predicted probabilities from logistic regression: different methods correspond to different target populations

BACKGROUND

We review three common methods to estimate predicted probabilities following confounder-adjusted logistic regression: marginal standardization (predicted probabilities summed to a weighted average reflecting the confounder distribution in the target population); prediction at the modes (conditional predicted probabilities calculated by setting each confounder to its modal value); and prediction at the means (predicted probabilities calculated by setting each confounder to its mean value). That each method corresponds to a different target population is underappreciated in practice. Specifically, prediction at the means is often incorrectly interpreted as estimating average probabilities for the overall study population, and furthermore yields nonsensical estimates in the presence of dichotomous confounders. Default commands in popular statistical software packages often lead to inadvertent misapplication of prediction at the means.

METHODS

Using an applied example, we demonstrate discrepancies in predicted probabilities across these methods, discuss implications for interpretation and provide syntax for SAS and Stata.

RESULTS

Marginal standardization allows inference to the total population from which data are drawn. Prediction at the modes or means allows inference only to the relevant stratum of observations. With dichotomous confounders, prediction at the means corresponds to a stratum that does not include any real-life observations.

CONCLUSIONS

Marginal standardization is the appropriate method when making inference to the overall population. Other methods should be used with caution, and prediction at the means should not be used with binary confounders. Stata, but not SAS, incorporates simple methods for marginal standardization.

The role of echocardiography in the management of patients with myxomatous disease

Degenerative mitral regurgitation (MR), the leading cause of organic MR in western countries, is primarily characterized by mitral valve prolapse but encompasses a wide spectrum of anatomic lesions from fibroelastic deficiency (localized prolapse segment often associated with ruptured chordae) to diffuse myxomatous degeneration (Barlow's disease, diffuse excessive tissue with multiple valvular segments involved). Echocardiography is the method of choice to evaluate patients with degenerative MR and plays a crucial role in clinical management. It allows accurate assessment of MR severity, left ventricular and atrial consequences, etiology, mechanisms and anatomic lesions and consequently defines the probability of mitral valve repair.

How do we use imaging to aid considerations for intervention in patients with severe mitral regurgitation?

Increasing life expectancy and comorbid conditions, like obesity, especially in industrialized countries, have led to Valvular Heart Disease (VHD) becoming a major epidemic. Mitral valve disease currently accounts for nearly 10% of Valvular Heart Disease in industrialized countries worldwide. It is a known fact that, left untreated, degenerative mitral valve disease not only shortens an individual's life, but is also associated with increased morbidity. Despite current guidelines, there is often marked delay in appropriately sending patients for consideration of surgical intervention-interventions that when performed well can dramatically restore patients to a more normal lifespan. The critical question is really not what the severity of the mitral regurgitation is, but what the effect of the mitral regurgitation is on the heart. Modern day echocardiography utilizing Transthoracic Echo, Stress Echo, and Transesophageal Echo, can provide the clinician and the surgeon with six key factors that when taken together provide clear direction as to the proper timing for consideration for mitral valve repair. Thinking of these in an integrative fashion, the clinician and the surgeon can more appropriately time proper surgical intervention in primary degenerative mitral regurgitation.

Material properties of aged human mitral valve leaflets

This study aimed to characterize the mechanical properties of aged human anterior mitral leaflets (AML) and posterior mitral leaflets (PML). The AML and PML samples from explanted human hearts (n = 21, mean age of 82.62 ± 8.77-years-old) were subjected to planar biaxial mechanical tests. The material stiffness, extensibility, and degree of anisotropy of the leaflet samples were quantified. The microstructure of the samples was assessed through histology. Both the AML and PML samples exhibited a nonlinear and anisotropic behavior with the circumferential direction being stiffer than the radial direction. The AML samples were significantly stiffer than the PML samples in both directions, suggesting that they should be modeled with separate sets of material properties in computational studies. Histological analysis indicated the changes in the tissue elastic constituents, including the fragmented and disorganized elastin network, the presence of fibrosis and proteoglycan/glycosaminoglycan infiltration and calcification, suggesting possible valvular degenerative characteristics in the aged human leaflet samples. Overall, stiffness increased and areal strain decreased with calcification severity. In addition, leaflet tissues from hypertensive individuals also exhibited a higher stiffness and low areal strain than normotensive individuals. There are significant differences in the mechanical properties of the two human mitral valve leaflets from this advanced age group. The morphologic changes in the tissue composition and structure also infer the structural and functional difference between aged human valves and those of animals.

Accuracy of a mitral valve segmentation method using J-splines for real-time 3D echocardiography data

Patient-specific models of the heart's mitral valve (MV) exhibit potential for surgical planning. While advances in 3D echocardiography (3DE) have provided adequate resolution to extract MV leaflet geometry, no study has quantitatively assessed the accuracy of their modeled leaflets vs. a ground-truth standard for temporal frames beyond systolic closure or for differing valvular dysfunctions. The accuracy of a 3DE-based segmentation methodology based on J-splines was assessed for porcine MVs with known 4D leaflet coordinates within a pulsatile simulator during closure, peak closure, and opening for a control, prolapsed, and billowing MV model. For all time points, the mean distance error between the segmented models and ground-truth data were 0.40 ± 0.32 mm, 0.52 ± 0.51 mm, and 0.74 ± 0.69 mm for the control, flail, and billowing models. For all models and temporal frames, 95% of the distance errors were below 1.64 mm. When applied to a patient data set, segmentation was able to confirm a regurgitant orifice and post-operative improvements in coaptation. This study provides an experimental platform for assessing the accuracy of an MV segmentation methodology at phases beyond systolic closure and for differing MV dysfunctions. Results demonstrate the accuracy of a MV segmentation methodology for the development of future surgical planning tools.

Single-centre experience with mitral valve repair in asymptomatic patients with severe mitral valve regurgitation

OBJECTIVES

Guidelines recommend surgical mitral valve repair in selected patients with asymptomatic severe mitral valve regurgitation (MR), but the role of repair remains a matter of debate. Survival analyses of operated asymptomatic patients have been reported, but long-term haemodynamics and quality of life are not well defined. The aim of this study was to report the long-term follow-up focusing on these aspects.

METHODS

Our database identified patients who underwent primary isolated mitral valve repair for severe MR and were asymptomatic by New York Heart Association Class I and in sinus rhythm. To obtain sufficient length of follow-up, only patients operated on before 2006 returned for an echocardiogram and quality-of-life assessment (SF-36).

RESULTS

Between May 1991 and December 2005, 46 asymptomatic patients with severe MR and a normal left ventricular function (ejection fraction >60%) were operated on. Mean age was 50.2 ± 13.2 years and 89% of patients were male. There were no operative deaths. Mean follow-up was 8.4 ± 3.9 years with 386 patient-years, survival was 93.3% at 12 years and comparable with the general age-matched Dutch population. Follow-up echocardiography showed that 92% had no to mild MR, and 3 patients had moderate MR. Left ventricular function was good/impaired/moderate in 66/29/5% of patients. Quality-of-life SF-36 assessment showed that mean physical and mental health components were 83 ± 17 and 79 ± 17, which was comparable with that of the general age- and gender-matched Dutch population.

CONCLUSIONS

Our experience shows that mitral valve repair for severe MR in asymptomatic patients is safe, and has satisfactory long-term survival with a low recurrence rate of MR, good left ventricular function, and excellent quality of life that is comparable with the general Dutch population.

Almanac 2012: adult cardiac surgery: the national society journals present selected research that has driven recent advances in clinical cardiology

This review covers the important publications in adult cardiac surgery in the last few years, including the current evidence base for surgical revascularisation and the use of off-pump surgery, bilateral internal mammary arteries and endoscopic vein harvesting. The changes in conventional aortic valve surgery are described alongside the outcomes of clinical trials and registries for transcatheter aortic valve implantation, and the introduction of less invasive and novel approaches of conventional aortic valve replacement surgery. Surgery for mitral valve disease is also considered, with particular reference to surgery for asymptomatic degenerative mitral regurgitation.

Surgical timing of degenerative mitral regurgitation: what to consider

Severe primary mitral regurgitation (MR) is a progressive condition which engenders significant mortality and morbidity if left untreated. The optimal timing of surgery in patients with MR of degenerative origin continues to be debated, especially for those who are asymptomatic. Apart from symptoms, current authoritative guidelines recommend intervention when there is incipient left ventricular dysfunction, pulmonary hypertension or new onset atrial fibrillation. This review focuses on the asymptomatic subject with severe MR, and examines contemporary clinical decision-making and management strategies, including the 2012 European guidelines on valvular heart disease. We discuss the rationale for risk stratifying the asymptomatic individual, and highlight current and novel diagnostic tools that may have a useful role, with an emphasis on echocardiographic imaging.

Early outcome of folding mitral valve repair technique without resection for mitral valve prolapse in 60 patients

OBJECTIVES

Leaflet resection represents the reference standard for mitral valve regurgitation. However, the resection technique is irreversible and requires leaflet cutting and reapproximation. Folding mitral valve repair is a nonresectional technique with inversion of the prolapsed segment into the left ventricle. The present study evaluated the effectiveness of this technique.

METHODS

The prolapsed segment was inverted into the left ventricle vertically. A pilot suture was placed at the free edge of the leaflet. After confirming no mitral valve regurgitation with a pressure test, additional sutures were placed toward the annulus. If the test still showed mitral valve regurgitation, the suture was removed and repositioned. Ring annuloplasty was performed in all patients, except those with active infectious endocarditis. The repaired mitral valve was evaluated using echocardiography.

RESULTS

A total of 60 patients (37 men; mean age, 62.4 years) underwent folding mitral valve repair from January 2007 to September 2011. Of these patients, 38 (63%) had moderate and 18 (30%) had severe mitral valve regurgitation preoperatively. Folding mitral valve repair was applied to the anterior leaflet and posterior leaflet. The mean cardiopulmonary bypass time and crossclamp time were 148 and 90 minutes, respectively. No patient had systolic anterior motion. Postoperative echocardiography revealed no mitral valve regurgitation to trivial mitral valve regurgitation in 48 and mild mitral valve regurgitation in 12 patients. No patient required reoperation for recurrent mitral valve regurgitation.

CONCLUSIONS

Folding mitral valve repair is an easily fine-tuned technique with a pilot suture, which can be easily removed and repositioned, if unsatisfactory. This reversibility is a significant advantage of this technique. Long-term follow-up is necessary to assess the durability of this technique.

A novel left heart simulator for the multi-modality characterization of native mitral valve geometry and fluid mechanics

Numerical models of the mitral valve have been used to elucidate mitral valve function and mechanics. These models have evolved from simple two-dimensional approximations to complex three-dimensional fully coupled fluid structure interaction models. However, to date these models lack direct one-to-one experimental validation. As computational solvers vary considerably, experimental benchmark data are critically important to ensure model accuracy. In this study, a novel left heart simulator was designed specifically for the validation of numerical mitral valve models. Several distinct experimental techniques were collectively performed to resolve mitral valve geometry and hemodynamics. In particular, micro-computed tomography was used to obtain accurate and high-resolution (39 μm voxel) native valvular anatomy, which included the mitral leaflets, chordae tendinae, and papillary muscles. Three-dimensional echocardiography was used to obtain systolic leaflet geometry. Stereoscopic digital particle image velocimetry provided all three components of fluid velocity through the mitral valve, resolved every 25 ms in the cardiac cycle. A strong central filling jet (V ~ 0.6 m/s) was observed during peak systole with minimal out-of-plane velocities. In addition, physiologic hemodynamic boundary conditions were defined and all data were synchronously acquired through a central trigger. Finally, the simulator is a precisely controlled environment, in which flow conditions and geometry can be systematically prescribed and resultant valvular function and hemodynamics assessed. Thus, this work represents the first comprehensive database of high fidelity experimental data, critical for extensive validation of mitral valve fluid structure interaction simulations.