Is repair preferable to replacement for ischemic mitral regurgitation?

Quantitative Evaluation of Annuloplasty on Mitral Valve Chordae Tendineae Forces to Supplement Surgical Planning Model Development

PURPOSE

Computational models of the heart's mitral valve (MV) exhibit potential for preoperative surgical planning in ischemic mitral regurgitation (IMR). However challenges exist in defining boundary conditions to accurately model the function and response of the chordae tendineae to both IMR and surgical annuloplasty repair. Towards this goal, a ground-truth data set was generated by quantifying the isolated effects of IMR and mitral annuloplasty on leaflet coaptation, regurgitation, and tethering forces of the anterior strut and posterior intermediary chordae tendineae.

METHODS

MVs were excised from ovine hearts (N=15) and mounted in a pulsatile heart simulator which has been demonstrated to mimic the systolic MV geometry and coaptation of healthy and chronic IMR sheep. Strut and intermediary chordae from both MV leaflets (N=4) were instrumented with force transducers. Tested conditions included a healthy control, IMR, oversized annuloplasty, true-sized annuloplasty, and undersized mitral annuloplasty. A2-P2 leaflet coaptation length, regurgitation, and chordal tethering were quantified and statistically compared across experimental conditions.

RESULTS

IMR was successfully simulated with significant increases in MR, tethering forces for each of the chordae, and decrease in leaflet coaptation (p<.05). Compared to the IMR condition, increasing levels of downsized annuloplasty significantly reduced regurgitation, increased coaptation, reduced posteromedial papillary muscle strut chordal forces, and reduced intermediary chordal forces from the anterolateral papillary muscle (p<.05).

CONCLUSIONS

These results provide for the first time a novel comprehensive data set for refining the ability of computational MV models to simulate IMR and varying sizes of complete rigid ring annuloplasty.

Ischemic mitral regurgitation: pathophysiology, diagnosis and surgical treatment

Ischemic mitral valve regurgitation often complicates acute myocardial infarction and also represents a negative prognostic factor for long-term survival in patients undergoing surgical myocardial revascularization. While severe mitral regurgitation should always be corrected during a coronary artery bypass operation, the decision making is more difficult in patients with a mild-to-moderate degree of regurgitation. Recent studies and experimental protocols have elucidated the pathophysiological mechanisms leading to mitral regurgitation with great interest in annular modifications and subvalvular alterations. These data suggest that new and integrated surgical approaches that address annuloplasty ring sizing, ring type selection and tethering phenomenon (i.e., chordal cutting, 'edge-to-edge' technique and left-ventricular plasty techniques) are required for a safer and durable valve repair. Transthoracic and transesophageal echocardiography are useful in determining the etiology and the degree of mitral regurgitation, to assess mitral deformation and to measure indexes of global and regional left-ventricular remodeling. Stress echocardiography may unmask higher degrees of mitral regurgitation. More data are needed in order to confirm the promising and interesting preliminary experimental findings of magnetic resonance imaging in diagnosis and clinical evaluation of ischemic mitral regurgitation.

Advances in percutaneous valvular intervention

We are entering a new era in the percutaneous treatment of valvular heart disease. Novel techniques and devices have given rise to the possible treatment of a range of valvular heart diseases that previously necessitated surgical therapies, including aortic stenosis, pulmonary regurgitation and mitral regurgitation. Despite the enormous potential of these percutaneous therapies, enthusiasm needs to be balanced by an understanding of the challenges that need to be overcome before such therapies can be widely embraced. This review provides a critical assessment of the status of the major developments in percutaneous valvular intervention to date, and provides the authors' perspective on the current role and future potential of these techniques.

Ischemic mitral regurgitation: mechanisms, intraoperative echocardiographic evaluation, and surgical considerations

Ischemic mitral regurgitation (IMR) is a subcategory of functional rather than organic, mitral valve (MV) disease. Whether reversible or permanent, left ventricular remodeling creates IMR that is complex and multifactorial. A comprehensive TEE examination in patients with IMR may have important implications for perioperative clinical decision making. Several TEE measures predictive of MV repair failure have been identified. Current practice among most surgeons is to typically repair the MV in patients with IMR. MV replacement is usually reserved for situations in which the valve cannot be reasonably repaired, or repair is unlikely to be tolerated clinically.

Low-dose dobutamine stress echocardiography cannot predict mitral regurgitation reversibility after coronary artery bypass grafting

BACKGROUND

The ideal management of ischemic mitral regurgitation (MR) remains a clinical dilemma because of the suboptimal available therapeutic options. Recently, new concepts have emerged, pointing to the benefits of a patient selection approach when debating the management of moderate ischemic MR. We investigated the predictability of low-dose dobutamine stress echocardiography (DSE) in selecting candidates for CABG with moderate MR for valve repair.

METHODS

From November 2002 to May 2010, 110 candidates for first-time CABG, who were admitted to the cardiac surgery department in Day General Hospital (Tehran, Iran), were enrolled in the present cross-sectional study. DSE was performed for each case before CABG. Those with positive findings underwent CABG alone and those with negative results underwent concomitant CABG and mitral valve repair. The patients were followed up for a minimum of 60 months.

RESULTS

Of the 110 patients, 47 (42.72%) had positive test results and underwent CABG alone and 63 (57.28%) had negative DSE results and underwent concomitant CABG and mitral valve repair. The MR degree had decreased from 2.8±0.3 preoperatively to 1.46±0.6 early during the hospital stay and 1.9±0.7 during late follow-up in the CABG group. It had decreased from 2.84±0.4 preoperatively to 0.93±0.65 postoperatively but then increased to 1.41±0.9 during late follow-up, for a significant decrease in the combined group (P<.05).

CONCLUSIONS

Despite its utility in selecting CABG patients with moderate ischemic MR for valve repair from a short-term perspective, the use of DSE cannot predict the long-term outcomes of these patients.

Mitral-valve repair versus replacement for severe ischemic mitral regurgitation

BACKGROUND

Ischemic mitral regurgitation is associated with a substantial risk of death. Practice guidelines recommend surgery for patients with a severe form of this condition but acknowledge that the supporting evidence for repair or replacement is limited.

METHODS

We randomly assigned 251 patients with severe ischemic mitral regurgitation to undergo either mitral-valve repair or chordal-sparing replacement in order to evaluate efficacy and safety. The primary end point was the left ventricular end-systolic volume index (LVESVI) at 12 months, as assessed with the use of a Wilcoxon rank-sum test in which deaths were categorized below the lowest LVESVI rank.

RESULTS

At 12 months, the mean LVESVI among surviving patients was 54.6±25.0 ml per square meter of body-surface area in the repair group and 60.7±31.5 ml per square meter in the replacement group (mean change from baseline, -6.6 and -6.8 ml per square meter, respectively). The rate of death was 14.3% in the repair group and 17.6% in the replacement group (hazard ratio with repair, 0.79; 95% confidence interval, 0.42 to 1.47; P=0.45 by the log-rank test). There was no significant between-group difference in LVESVI after adjustment for death (z score, 1.33; P=0.18). The rate of moderate or severe recurrence of mitral regurgitation at 12 months was higher in the repair group than in the replacement group (32.6% vs. 2.3%, P<0.001). There were no significant between-group differences in the rate of a composite of major adverse cardiac or cerebrovascular events, in functional status, or in quality of life at 12 months.

CONCLUSIONS

We observed no significant difference in left ventricular reverse remodeling or survival at 12 months between patients who underwent mitral-valve repair and those who underwent mitral-valve replacement. Replacement provided a more durable correction of mitral regurgitation, but there was no significant between-group difference in clinical outcomes. (Funded by the National Institutes of Health and the Canadian Institutes of Health; ClinicalTrials.gov number, NCT00807040.).

Similar survival after mitral valve replacement or repair for ischemic mitral regurgitation: a meta-analysis

BACKGROUND

Ischemic mitral regurgitation (IMR) occurs in 20% of patients after myocardial infarction. There is no agreement as to the best surgical option. With no prospective randomized controlled trials available, our objective was to perform a meta-analysis comparing replacement and repair.

METHODS

A literature search was performed in PubMed, EMBASE, Ovid, and Google Scholar. The following keywords were included: "ischemic mitral regurgitation" and "repair or replacement." Inclusion and exclusion criteria were used to reflect current surgical practice (subvalvular preservation, ring annuloplasty). Primary outcomes of interest were operative mortality and survival. Secondary outcomes analyzed were change in ejection fraction (EF), left ventricular (LV) dimensions, New York Heart Association (NYHA) class, reoperation rate, and 2+ or greater recurrence of mitral regurgitation.

RESULTS

Of 280 articles, only 12 satisfied all inclusion and exclusion criteria. These articles included 2,508 patients, 64% of whom received valve replacement. Operative mortality was lower after repair (odds ratio [OR], 0.56; 95% confidence interval [CI], 0.38-0.85; p = 0.001); no difference was found when only articles with patients operated on mainly after 1998 were included (OR, 0.70; 95% CI, 0.44 -1.12; p = 0.14). Survival was similar (hazard ratio [HR], 0.86; 95% CI, 0.66-1.13; p = 0.28). No differences in EF, ventricular dimensions, NYHA class, and reoperation were found. Regurgitation recurrence was higher in the repair group (OR, 7.51; 95% CI, 3.7-15.23; p < 0.001).

CONCLUSIONS

Mitral valve repair is associated with lower operative mortality but higher recurrence of regurgitation in patients with ischemic mitral regurgitation. No differences were found regarding survival, NYHA class, and functional indicators.

Ring annuloplasty for ischemic mitral regurgitation: A single center experience

Background

Ischemic mitral regurgitation associated with coronary artery disease presents a management challenge to cardiac surgeons. We report our early and midterm results of chronic ischemic mitral regurgitation treated with concomitant mitral ring annuloplasty and coronary artery bypass grafting.

Methods

We performed a retrospective review of the medical records of patients who underwent coronary artery bypass grafting at our institute from January 2009 to December 2011. Data were collected in 50 patients with chronic ischemic mitral regurgitation who had mitral ring annuloplasty along with coronary artery bypass grafting. Preoperative data, echocardiographic findings, operative procedure, outcome, and perioperative hemodynamics were analyzed. Early and intermediate follow-up data were also collected and analyzed.

Results

There were 3 (6%) early and 9 (18%) late deaths. Of the survivors, 38 (76%) had a significant reduction in left ventricular end-diastolic and end-systolic dimensions and improvement in New York Heart Association functional class.

Conclusion

Despite a risk of residual regurgitation, mitral ring annuloplasty combined with coronary artery bypass appears to be a good treatment option in selected patients with chronic ischemic mitral regurgitation.

Concomitant off-pump coronary artery bypass grafting results in improved in-hospital outcomes for patients with ischemic mitral regurgitation undergoing surgery

OBJECTIVE

Surgical management of ischemic mitral regurgitation (IMR) has primarily consisted of revascularization with or without the addition of mitral valve repair or replacement. We hypothesize that performing off-pump coronary artery bypass (OPCAB) grafting before fixing MR improves in-hospital outcomes for patients with IMR undergoing surgery.

METHODS

From January 2000 through December 2010, a total of 96 consecutive patients with moderate or severe IMR, as determined by preoperative echocardiography, underwent on-pump coronary artery bypass grafting (CABG) (n = 66) or OPCAB (n = 30) revascularization with concomitant mitral valve repair or replacement. A retrospective analysis of a prospectively collected cardiac surgery database (PATS; Dendrite Clinical Systems, Oxford, UK) was performed. In addition, medical notes and charts were reviewed for all study patients.

RESULTS

The 2 groups had similar preoperative demographic and EuroSCORE risk-stratification characteristics. The operative mortality rate for the entire cohort was 9.4%. Patients who underwent OPCAB grafting had a lower operative mortality than those who underwent CABG (3.3% versus 12.1%; P = .006). The mean ±SD cardiopulmonary bypass time (82.7 ± 34.7 minutes versus 160.7 ± 45.2 minutes; P < .001) and cross-clamp time (49.0 ± 22.4 minutes versus 103.4 ± 39.5 minutes; P < .001) were significantly shorter in the off-pump group than in the on-pump group. The OPCAB group also had significantly less in-hospital morbidity and shorter stays in the intensive care unit and the hospital.

CONCLUSION

Our analysis shows that OPCAB grafting (compared with conventional CABG) before repairing MR is associated with favorable in-hospital outcomes for patients undergoing surgery for IMR.

Three-dimensional valve repair-the better care? Midterm results of a saddle-shaped, rigid annuloplasty ring in patients with ischemic mitral regurgitation

OBJECTIVES

Undersized ring annuloplasty is the treatment of choice for functional mitral regurgitation. However, recurrence of mitral regurgitation within the first years is frequent. The aim of this study was to analyze the functional and clinical outcome after mitral valve repair with the 3-dimensional saddle-shaped Edwards GeoForm (Edwards Lifesciences LLC, Irvine, Calif) annuloplasty ring in patients with ischemic mitral regurgitation.

METHODS

Between November 2006 and November 2012, 70 patients (mean age, 68 ± 10 years; mean left ventricular ejection fraction, 40% ± 15%) with functional mitral regurgitation due to ischemic cardiomyopathy underwent mitral valve repair with the Edwards GeoForm annuloplasty ring. Concomitant procedures, such as coronary artery bypass grafting (75.7%), tricuspid valve repair (25.7%), aortic valve replacement (8.6%), and the Maze procedure (4.3%), were performed in 92.9% of patients. Follow-up is 97% complete (mean, 3.0 ± 1.7 years). Transthoracic echocardiography was obtained 2.4 ± 1.7 years postoperatively.

RESULTS

Thirty-day mortality was 5.9%. Overall survival at 5 years was 71.3% ± 6.9%. At 4 years, overall freedom from recurrence of mitral regurgitation grade 3+ or greater was 92.5% ± 3.6%, and freedom from recurrence of mitral regurgitation grade 2+ or greater was 71.0% ± 8.7%. Three patients required a mitral valve-related reoperation for ring dehiscence. New York Heart Association functional class improved from 3.6 ± 0.6 to 1.6 ± 0.6 during follow-up (P < .05). Mean mitral valve pressure gradient was 3.3 ± 1.8 mm Hg across all ring sizes at the time of follow-up.

CONCLUSIONS

Mitral valve repair with the 3-dimensional saddle-shaped Edwards GeoForm annuloplasty ring in case of ischemic mitral regurgitation shows a low rate of recurrent regurgitation at 4 years. Clinically relevant mitral stenosis was not detected. The importance of secure anchoring of the device in the mitral annulus has to be emphasized to prevent ring dehiscence.

Surgical options for the management of ischemic cardiomyopathy

OPINION STATEMENT

Novel surgical alternatives and the refinement of conventional surgical therapies for the treatment of ischemic cardiomyopathy are in constant evolution. Current approaches involve the determined application of the appropriateness criteria for CABG surgery, the extension of mitral valve repair to complex patients with ischemic cardiomyopathy, finding appropriate patients who might benefit from surgical ventricular reconstruction, and surgical attempts to regenerate lost or damaged myocardium with transplanted stem cells. The refinement of surgical techniques and the medical optimization of candidates for surgery remain a cornerstone of management for patients with complex heart disease like ischemic cardiomyopathy. The horizon is bright for patients suffering from this condition and concentrated research efforts by groups such as the NHLBI-sponsored Cardiothoracic Surgery Network will have a major impact on the future of patients with heart disease.

Mitral valve replacement versus annuloplasty for treating severe functional mitral regurgitation

OBJECTIVES

To improve the clinical outcome of patients with severe functional mitral regurgitation (FMR) associated with ischemic cardiomyopathy (ICM), we compared the therapeutic efficacy of mitral annuloplasty (MAP) with that of mitral valve replacement (MVR).

METHODS

In a retrospective observation 63 consecutive patients underwent mitral valve surgery for severe ICM-FMR from November 1999 to March 2012. All patients had severe FMR (regurgitant volume >60 ml/beat) with Carpentier type I and type IIIb disease. Mean RV was 74.0 ± 35.0 ml/beat and coaptation depth was 12.7 ± 3.0 mm. Twenty-six patients (41.3 %) were treated by MVR with sparing of the subvalvular apparatus and 37 (58.7 %) by MAP.

RESULTS

Total in-hospital mortality was 6.3 %. Kaplan-Meier survival estimates at 1 and 5 years were 84.2 and 78.6 % in the MVR group and 82.6 and 71.6 % in the MAP group, with no significant difference between groups (p = 0.758). Freedom from major adverse cardiac and cerebrovascular events (MACCE) at 5 years was 66.9 % for patients treated by MVR and 64.1 % for those treated by MAP (p = 0.866). At the last follow-up visit, >grade II MR had recurred in 4 annuloplasty patients (10.8 %). In multivariate analysis, independent predictors of increased late death and MACCE were significantly associated with residual pulmonary hypertension (late death: odds ratio = 25.0, p = 0.0009; MACCE: odds ratio = 31.3, p = 0.0001).

CONCLUSIONS

Mitral valve replacement with sparing of the subvalvular apparatus is a safe and effective surgical alternative for patients with severe FMR.

Mitral transcatheter technologies

Mitral valve regurgitation (MR) is often diagnosed in patients with heart failure and is associated with worsening of symptoms and reduced survival. While surgery remains the gold standard treatment in low-risk patients with degenerative MR, in high-risk patients and in those with functional MR, transcatheter procedures are emerging as an alternative therapeutic option. MitraClip(®) is the device with which the largest clinical experience has been gained to date, as it offers sustained clinical benefit in selected patients. Further to MitraClip implantation, several additional approaches are developing, to better match with the extreme variability of mitral valve disease. Not only repair is evolving, initial steps towards percutaneous mitral valve implantation have already been undertaken, and initial clinical experience has just started.

Surgical management of ischemic mitral regurgitation: indications, procedures, and future prospects

Ischemic mitral regurgitation (IMR) is one of the most important risk factors affecting prognosis of patients who suffer from myocardial infarction. The mechanisms of IMR, the indications for surgical intervention, the operative procedures, and the limitations of surgical procedures are discussed in this review article.

Generating new knowledge in cardiac interventions

Cardiac interventions are among the most quantitatively studied therapies. It is important for all involved with cardiac interventions to understand how information generated from observations made during patient care is transformed into data suitable for analysis, to appreciate at a high level what constitutes appropriate analyses of those data, to effectively evaluate inferences drawn from those analyses, and to apply new knowledge to better care for individual patients.

Mechanics of the mitral annulus in chronic ischemic cardiomyopathy

Approximately one third of all patients undergoing open-heart surgery for repair of ischemic mitral regurgitation present with residual and recurrent mitral valve leakage upon follow up. A fundamental quantitative understanding of mitral valve remodeling following myocardial infarction may hold the key to improved medical devices and better treatment outcomes. Here we quantify mitral annular strains and curvature in nine sheep 5 ± 1 weeks after controlled inferior myocardial infarction of the left ventricle. We complement our marker-based mechanical analysis of the remodeling mitral valve by common clinical measures of annular geometry before and after the infarct. After 5 ± 1 weeks, the mitral annulus dilated in septal-lateral direction by 15.2% (p = 0.003) and in commissure-commissure direction by 14.2% (p < 0.001). The septal annulus dilated by 10.4% (p = 0.013) and the lateral annulus dilated by 18.4% (p < 0.001). Remarkably, in animals with large degree of mitral regurgitation and annular remodeling, the annulus dilated asymmetrically with larger distortions toward the lateral-posterior segment. Strain analysis revealed average tensile strains of 25% over most of the annulus with exception for the lateral-posterior segment, where tensile strains were 50% and higher. Annular dilation and peak strains were closely correlated to the degree of mitral regurgitation. A complementary relative curvature analysis revealed a homogenous curvature decrease associated with significant annular circularization. All curvature profiles displayed distinct points of peak curvature disturbing the overall homogenous pattern. These hinge points may be the mechanistic origin for the asymmetric annular deformation following inferior myocardial infarction. In the future, this new insight into the mechanism of asymmetric annular dilation may support improved device designs and possibly aid surgeons in reconstructing healthy annular geometry during mitral valve repair.

Finite element analysis of the biomechanical interaction between coronary sinus and proximal anchoring stent in coronary sinus annuloplasty

Recent clinical studies of the percutaneous transvenous mitral annuloplasty (PTMA) devices have shown a short-term reduction of mitral regurgitation after implantation. However, adverse events associated with the devices such as compression and perforation of vessel branches, device migration and fracture were reported. In this study, a finite element analysis was carried out to investigate the biomechanical interaction between the proximal anchor stent of a PTMA device and the coronary sinus (CS) vessel in three steps including: (i) the stent release and contact with the CS wall, (ii) the axial pull t the stent connector and (iii) the pressure inflation of the vessel wall. To investigate the impact of the material properties of tissues and stents on the interactive responses, the CS vessel was modelled with human and porcine material properties, and the proximal stent was modelled with two different Nitinol materials with one being stiffer than the other. The results indicated that the vessel wall stresses and contact forces imposed by the stents were much higher in the human model than the porcine model. However, the mechanical differences induced by the two stent types were relatively small. The softer stent exhibited a better fatigue safety factor when deployed in the human model than in the porcine model. These results underscored the importance of the CS tissue mechanical properties. Vessel wall stress and stent radial force obtained in the human model were higher than those obtained in the porcine model, which also brought up questions as to the validity of using the porcine model to assess device mechanical function. The quantification of these biomechanical interactions can offer scientific insight into the development and optimisation of the PTMA device design.

Active mitral ring for post-surgical remote correction of residual mitral regurgitation on the beating heart

OBJECTIVES

Residual mitral regurgitation after valve repair worsens patients' clinical outcome. Postimplant adjustable mitral rings potentially address this issue, allowing the reshaping of the annulus on the beating heart under echocardiography control. We developed an original mitral ring allowing valve geometry remodelling after the implantation and designed an animal study to assess device effectiveness in correcting residual mitral regurgitation.

METHODS

The device consists of two concentric rings: one internal and flexible, sutured to the mitral annulus and a second external and rigid. A third conic element slides between the two rings, modifying the shape of the flexible ring. This sliding element is remotely activated with a rotating tool. Animal model: in adult swine, under cardio pulmonary bypass and cardiac arrest, we shortened the primary chordae of P2 segment to reproduce Type III regurgitation and implanted the active ring. We used intracardiac ultrasound to assess mitral regurgitation and the efficacy of the active ring to correct it.

RESULTS

Severe mitral regurgitation (3+ and 4+) was induced in eight animals, 54 ± 6 kg in weight. Vena contracta width decreased from 0.8 ± 0.2 to 0.1 cm; proximal isovelocity surface area radius decreased from 0.8 ± 0.2 to 0.1 cm and effective regurgitant orifice area decreased from 0.50 ± 0.1 to 0.1 ± 0.1 cm(2). Six animals had a reversal of systolic pulmonary flow that normalized following the activation of the device. All corrections were reversible.

CONCLUSIONS

Postimplant adjustable mitral ring corrects severe mitral regurgitation through the reversible modification of the annulus geometry on the beating heart. It addresses the frequent and morbid issue of recurrent mitral valve regurgitation.

Coronary artery bypass surgery with or without mitral valve annuloplasty in moderate functional ischemic mitral regurgitation: final results of the Randomized Ischemic Mitral Evaluation (RIME) trial

BACKGROUND

The role of mitral valve repair (MVR) during coronary artery bypass grafting (CABG) in patients with moderate ischemic mitral regurgitation (MR) is uncertain. We conducted a randomized, controlled trial to determine whether repairing the mitral valve during CABG may improve functional capacity and left ventricular reverse remodeling compared with CABG alone.

METHODS AND RESULTS

Seventy-three patients referred for CABG with moderate ischemic MR and an ejection fraction >30% were randomized to receive CABG plus MVR (34 patients) or CABG only (39 patients). The study was stopped early after review of interim data. At 1 year, there was a greater improvement in the primary end point of peak oxygen consumption in the CABG plus MVR group compared with the CABG group (3.3 mL/kg/min versus 0.8 mL/kg/min; P<0.001). There was also a greater improvement in the secondary end points in the CABG plus MVR group compared with the CABG group: left ventricular end-systolic volume index, MR volume, and plasma B-type natriuretic peptide reduction of 22.2 mL/m(2), 28.2 mL/beat, and 557.4 pg/mL, respectively versus 4.4 mL/m(2) (P=0.002), 9.2 mL/beat (P=0.001), and 394.7 pg/mL (P=0.003), respectively. Operation duration, blood transfusion, intubation duration, and hospital stay duration were greater in the CABG plus MVR group. Deaths at 30 days and 1 year were similar in both groups: 3% and 9%, respectively in the CABG plus MVR group, versus 3% (P=1.00) and 5% (P=0.66), respectively in the CABG group.

CONCLUSIONS

Adding mitral annuloplasty to CABG in patients with moderate ischemic MR may improve functional capacity, left ventricular reverse remodeling, MR severity, and B-type natriuretic peptide levels, compared with CABG alone. The impact of these benefits on longer term clinical outcomes remains to be defined.

Mitral valve repair or replacement for ischemic mitral regurgitation? The Italian Study on the Treatment of Ischemic Mitral Regurgitation (ISTIMIR)

OBJECTIVE

It is uncertain whether mitral valve replacement is really inferior to mitral valve repair for the treatment of chronic ischemic mitral regurgitation. This multicenter study aimed at providing a contribution to this issue.

METHODS

Of 1006 patients with chronic ischemic mitral regurgitation and impaired left ventricular function (ejection fraction < 40%) operated on at 13 Italian institutions between 1996 and 2011, 298 (29.6%) underwent mitral valve replacement whereas 708 (70.4%) received mitral valve repair. Propensity scores were calculated by a nonparsimonious multivariable logistic regression, and 244 pairs of patients were matched successfully using calipers of width 0.2 standard deviation of the logit of the propensity scores. The postmatching median standardized difference was 0.024 (range, 0-0.037) and in none of the covariates did it exceed 10%.

RESULTS

Early deaths were 3.3% (n = 8) in mitral valve repair versus 5.3% (n = 13) in mitral valve replacement (P = .32). Eight-year survival was 81.6% ± 2.8% and 79.6% ± 4.8% (P = .42), respectively. Actual freedom from all-cause reoperation and valve-related reoperation were 64.3% ± 4.3% versus 80% ± 4.1%, and 71.3% ± 3.5% versus 85.5% ± 3.9 in mitral valve repair and mitral valve replacement, respectively (P < .001). Actual freedom from all valve-related complications was 68.3% ± 3.1% versus 69.9% ± 3.3% in mitral valve repair and mitral valve replacement, respectively (P = .78). Left ventricular function did not improved significantly, and it was comparable in the 2 groups postoperatively (36.9% vs 38.5%, P = .66). At competing regression analysis, mitral valve repair was a strong predictor of reoperation (hazard ratio, 2.84; P < .001).

CONCLUSIONS

Mitral valve replacement is a suitable option for patients with chronic ischemic mitral regurgitation and impaired left ventricular function. It provides better results in terms of freedom from reoperation with comparable valve-related complication rates.

Mitral valve surgery for dilated cardiomyopathy: current status and future roles

There are a large number of patients with functional mitral regurgitation resulting from dilated cardiomyopathy. The decision between surgical correction and medical management of severe mitral regurgitation in heart failure can be difficult. The data regarding long-term benefits and mortality after surgical intervention are contradictory. Recent data suggest that mitral regurgitation can be surgically corrected in heart failure with symptomatic improvements and beneficial reverse remodeling. Contrary to prior beliefs, mitral valve repair can be performed safely with minimal postoperative mortality. Data from multi-institutional, randomized prospective trials will help to elucidate many of the questions and concerns regarding repair of severe functional mitral regurgitation.

Mild functional ischemic mitral regurgitation following acute coronary syndrome: a retrospective study

Background:

Ischemic mitral regurgitation is a frequent complication of acute coronary syndrome. It primarily occurs in patients with a prior myocardial infarction but also may be seen with acute ischemia, a setting in which the MR typically resolves after the ischemia resolves. The vast majority of patients have “functional” ischemic MR. In these individuals, the papillary muscles, chordae, and valve leaflets are normal. However, the leaflets do not coapt and restricted leaflet motion is frequently noted on echocardiography. Ischemic mitral regurgitation indicates a poor prognosis after acute myocardial infarction. This study addresses the clinical characteristics of patients of acute coronary syndrome with mild functional ischemic mitral regurgitation and its impact on immediate in-hospital cardiovascular outcomes and death.

Patients and Methods:

From March 2006 through May 2007, patients who underwent 2-dimensional (2D) color doppler echocardiographic quantification of ischemic mitral regurgitation within 10 days of admission for acute coronary syndrome (ACS) in Manipal Teaching Hospital, a tertiary hospital in the western region of Nepal were noted. The demographic details, conventional risk factors of coronary artery disease, clinical and laboratory findings, treatment course and in-hospital outcomes of all the patients with mild functional ischemic MR following ACS in that time duration were recorded in a designated Performa. A total of 94 patients enrolled in the study were divided into two groups: Group I with mild functional ischemic MR and Group II without MR on 2D echocardigraphic assessment. Patient characteristics, risk factors, ejection fraction, and cardiovascular outcome and death among the two groups were compared and analyzed using software package SPSS 17.0 version.

Results:

Group I constituted 64.89% of the study population and Group II comprised of 35.11%. The patients in Group I was more likely to be elderly diabetic (P<0.05), and smokers with hypertension (P < 0.05). Mild functional ischemic MR was more common in patients with STEMI as compared to those with unstable angina and NSTEMI (55.7%, 36.1%, and 8.2%; P < 0.05).The mean ejection fraction in the first group was 54.84% in contrast to 58.92% observed in group II (P < 0.05).The type of wall involvement inferred from EKG analysis was homogeneously distributed in both the groups. Finally, there was no difference in immediate in-hospital (within 10 days) mortality or cardiovascular outcomes (heart failure, ventricular tachycardia/fibrillation, hypotension, and cardiogenic shock) between these two groups.

Conclusion:

Ischemic mitral regurgitation following acute coronary syndromeare more likely in elderly diabetics and hypertensive smokers. It is a more common finding in STEMI. Although mild MR following ACS does reduce ejection fraction, the immediate (within 10 days) in-hospital mortality and cardiovascular outcomes are not significantly altered.

Surgical approaches to mitral regurgitation

Surgical approaches to correct mitral regurgitation (MR) have evolved over 50 years and form much of the basis for percutaneous approaches to the mitral valve. Surgical mitral repairs have been more durable with use of annuloplasty, but recurrent regurgitation not resulting in reoperation can occur. The mitral leaflets may be resected or augmented, with recent trends to preserve leaflet coaptation surfaces if possible. Mitral chords tend to be replaced or transferred instead of being shortened. Mitral replacement still has a role when more durable and reliable than repair. Surgical incisions have varied from full sternotomy down to percutaneous access only, with less invasiveness usually requiring a trade-off versus effectiveness or ease of application. Less invasive options in treating MR may encourage higher-risk patients to seek anatomic therapy, whether surgical or percutaneous. Rapidly evolving technology will continue to be a dominant driver of surgical approaches to MR, with increasing overlap and interaction with percutaneous approaches.

Implantation of a new mitral ring, adjustable during follow-up: a simplified technique

Mitral valve repair for ischaemic mitral incompetence has a 10% rate of failure at ten year follow-up. Progressive annular dilation could play an important role. We have implanted the enCor(SQ)(TM) mitral valve repair system. This system can be downsized during follow-up with the appropriate activation via the lead passed through the left atrium suture line, in order to restore mitral leaflet coaptation.

Ischemic mitral regurgitation: not only a bystander

Ischemic mitral regurgitation (MR) is a common complication of left ventricular (LV) dysfunction related to chronic coronary artery disease. This complex multifactorial disease involves global and regional LV remodeling, as well as dysfunction and distortion of the components of the mitral valve including the chordae, the annulus, and the leaflets. Its occurrence is associated with a poor prognosis. The suboptimal results obtained with the most commonly used surgical strategy, involving mitral valve annuloplasty with coronary bypass grafting, emphasize the need to develop alternative surgical techniques targeting the causal mechanisms of the disease. A comprehensive preoperative assessment of mitral valve configuration and LV geometry and function and an accurate quantification of MR severity at rest and during exercise may contribute to improve risk stratification and to tailor the surgical strategy according to the individual characteristics of the patient.

Surgical treatment of functional mitral regurgitation

Incidence of functional mitral regurgitation (FMR) is increasing due to aging and better survival after acute myocardial infarction, the most frequent cause of FMR. At the basis of FMR there is a displacement of one of both papillary muscle(s) and/or annular enlargement, which can be primitive or, more often, secondary. There is general agreement that its natural history is unfavorable, as witnessed by a considerable body of evidences. However, even if there is no clear evidence that surgical treatment of FMR changes consistently the outcome of patients with this disease, at least in terms of survival, there are some studies which show that function improves, as well as the global quality of life. The guidelines reflect this uncertainty, providing no clear indications, even in the gradation of severity of the FMR. Surgical techniques are variable and are mainly addressed to the annulus (restrictive annuloplasty), which is only a part of the anatomic problem related to FMR. Insertion of a prosthesis inside the native valve is appearing more and more a valuable option rather than a bail out procedure. On the other side, techniques addressed to modify the position of the papillary muscles appear to be still under investigation and not yet in the armamentarium of surgical treatment of FMR. Even after many years, rules are not established and results are fluctuating, but how and when to treat FMR is becoming more and more a topic of interest in cardiac surgery.

EVEREST II randomized clinical trial: predictors of mitral valve replacement in de novo surgery or after the MitraClip procedure

OBJECTIVE

The Endovascular Valve Edge-to-Edge Repair Study (EVEREST II) is a prospective, multicenter, randomized controlled trial comparing percutaneous repair with the MitraClip device to mitral valve (MV) surgery in the treatment of mitral regurgitation. The present study analyzed the patient characteristics and treatment effects on mitral repair versus replacement.

METHODS

Of 279 patients enrolled, 80 surgical patients underwent 82 MV operations and 178 underwent an initial MitraClip procedure, of whom 37 underwent a subsequent MV operation within 1 year of their index the MitraClip procedure. A logistic regression model was used to predict MV replacement according to valve pathology, etiology of mitral regurgitation, age, previous cardiac surgery, and treatment group.

RESULTS

The rate of percutaneous or surgical MV repair at 1 year was 89% (158/178) in patients initially receiving the MitraClip device versus 84% (67/80) in the surgical patients (P = .36). Surgical repair was performed after the MitraClip procedure in 20 (54%) of 37 patients (P < .001 vs surgery). In both the MitraClip device and surgery groups, MV replacement was significantly associated with anterior leaflet pathology (P = .035). Logistic regression analysis showed that anterior leaflet pathology predicted MV replacement. In 5 (13.5%) of 37 patients undergoing surgery after MitraClip therapy, replacement was performed in part because of MV injury associated with the MitraClip procedure.

CONCLUSIONS

These data suggest that anterior leaflet pathology is strongly associated with MV replacement in patients undergoing either de novo MV surgery or surgery after MitraClip therapy. MitraClip therapy has a repair rate similar to surgery through 1 year but also imparts a risk of replacement of a potentially repairable valve.

Management of mitral regurgitation during left ventricular reconstruction for ischemic heart failure

OBJECTIVE

Remodeling of the left ventricle (LV) in ischemic cardiomyopathy frequently leads to functional mitral regurgitation (MR). The indication for correcting MR in patients undergoing LV reconstruction (LVR) is unclear. In this study, we evaluated our strategy of correcting MR≥grade 2+ by restrictive mitral annuloplasty (RMA) during LVR.

METHODS

We studied 92 consecutive patients (76 men, mean age 61±10 years) who underwent LVR for ischemic heart failure (IHF). RMA was performed in all patients with MR≥grade 2+ on preoperative echocardiography and in patients who showed increased MR to ≥grade 2+ immediately after LVR. Patients were attributed to a RMA and no-RMA group, depending on whether or not concomitant RMA had been performed. Mean clinical and structured echocardiographic follow-up was 47±20 months and was 100% complete.

RESULTS

In 38 out of 40 patients (95%) with preoperative MR≥grade 2+, concomitant RMA was planned and performed. In 17 out of 52 patients (33%) with MR<grade 2+ preoperatively, MR increased after LVR to ≥grade 2+ leading to additional RMA during a second period of aortic cross-clamping. Early mortality in the RMA group (n=55) was 12.7% and survival at 36 months 78.2±11.2%. Early mortality in the no-RMA group (n=37) was 5.4% and survival at 36 months 81.1±12.8%. Patients in the RMA group had significantly more reduced LV function with greater LV dimensions and volumes preoperatively. Echocardiography demonstrated sustained improvement in LVEF with reduction of LV volumes in both patient groups. Recurrence of MR at late follow-up was observed in 2 patients (1 patient per group).

CONCLUSIONS

Patients with IHF eligible for LV reconstruction have MR≥grade 2+ in 44% of cases. In one-third of IHF patients with MR<grade 2+ preoperatively, MR increases to ≥grade 2+ after LVR. Concomitant mitral valve repair for MR≥grade 2+, on either preoperative echocardiography or immediately after LVR, results in favorable late clinical and echocardiographic outcome that proved to be similar to patients without concomitant mitral valve repair, despite more advanced disease.

Mitral replacement or repair for functional mitral regurgitation in dilated and ischemic cardiomyopathy: is it really the same?

BACKGROUND

This was a study to compare the results of mitral valve (MV) repair and MV replacement for the treatment of functional mitral regurgitation (MR) in advanced dilated and ischemic cardiomyopathy (DCM).

METHODS

One-hundred and thirty-two patients with severe functional MR and systolic dysfunction (mean ejection fraction 0.32 ± 0.078) underwent mitral surgery in the same time frame. The decision to replace rather than repair the MV was taken when 1 or more echocardiographic predictors of repair failure were identified at the preoperative echocardiogram. Eighty-five patients (64.4%) received MV repair and 47 patients (35.6%) received MV replacement. Preoperative characteristics were comparable between the 2 groups. Only ejection fraction was significantly lower in the MV repair group (0.308 ± 0.077 vs 0.336 ± 0.076, p = 0.04).

RESULTS

Hospital mortality was 2.3% for MV repair and 12.5% for MV replacement (p = 0.03). Actuarial survival at 2.5 years was 92 ± 3.2% for MV repair and 73 ± 7.9% for MV replacement (p = 0.02). At a mean follow-up of 2.3 years (median, 1.6 years), in the MV repair group LVEF significantly increased (from 0.308 ± 0.077 to 0.382 ± 0.095, p < 0.0001) and LV dimensions significantly decreased (p = 0.0001). On the other hand, in the MV replacement group LVEF did not significantly change (from 0.336 ± 0.076 to 0.31 ± 0.11, p = 0.56) and the reduction of LV dimensions was not significant. Mitral valve replacement was identified as the only predictor of hospital (odds ratio, 6; 95% confidence interval, 1.1 to 31; p = 0.03) and overall mortality (hazard ratio, 3.1; 95% confidence interval, 1.1 to 8.9; p = 0.02).

CONCLUSIONS

In patients with advanced dilated and ischemic cardiomyopathy and severe functional MR, MV replacement is associated with higher in-hospital and late mortality compared with MV repair. Therefore, mitral repair should be preferred whenever possible in this clinical setting.

The influence of saddle-shaped annuloplasty on leaflet curvature in patients with ischaemic mitral regurgitation

OBJECTIVES

Reports indicate that repair procedures for ischaemic mitral regurgitation (IMR) are less durable than previously thought. Repair failure has been shown to be stress related. Leaflet curvature is the major determinant of valve stress. Theoretical and animal experiments have shown that saddle-shaped annuloplasty optimizes leaflet curvature when compared with standard flat ring annuloplasty. Despite this, the influence of the ring shape on leaflet curvature has not been described in patients with IMR. This study uses real-time three-dimensional echocardiography (rt-3DE) to assess the influence of the ring shape on leaflet curvature.

METHODS

Rt-3DE was performed in 21 patients with IMR after placement of either a flat (n = 10, CE-Physio, Edwards) or saddle-shaped (n = 11, Profile 3D, Medtronic) annuloplasty ring. A combination of commercially available and customized software was used to measure multiple leaflet curvature parameters across all regions of the mitral valve.

RESULTS

Independently of the shape of the annuloplasty ring, all patients were subject to the same degree of annular undersizing. Patients who received saddle-shaped annuloplasty rings had greater leaflet curvature in all six mitral valve leaflet regions (A1 = 0.36 ± 0.10, A2 = 0.53 ± 0.13, A3 = 0.47 ± 0.13, P1 = 0.35 ± 0.23, P2 = 0.53 ± 0.34, P3 = 0.42 ± 0.20 cm(-2)) compared with patients who received flat annuloplasty rings (A1 = 0.16 ± 0.11, A2 = 0.18 ± 0.09, A3 = 0.16 ± 0.11, P1 = 0.20 ± 0.17, P2 = 0.21 ± 0.11, P3 = 0.18 ± 0.13 cm(-2)). These differences were statistically significant in all regions except the P1 region.

CONCLUSIONS

Saddle-shaped annuloplasty rings increase leaflet curvature compared with flat rings in patients with IMR. As a result, saddle-shaped annuloplasty may decrease leaflet stress and potentially increases the durability of the repair in patients with IMR.

Contemporary outcomes for surgical mitral valve repair: a benchmark for evaluating emerging mitral valve technology

OBJECTIVE

The emergence of transcatheter approaches to mitral valve (MV) repair has focused attention on outcomes after surgical MV repair. Results from the EVEREST II trial demonstrated worse short-term major adverse event (MAE) rates for surgical repair. This study analyzes contemporary outcomes of surgical MV repair to establish a benchmark for future therapeutic comparisons.

METHODS

From 2003 to 2008, 903 isolated MV repair operations were performed at 13 different statewide cardiac centers. Patients were excluded if they had prior valve operations or mitral stenosis similar to EVEREST II. MAE rate was defined using similar criteria to EVEREST II, including postoperative atrial fibrillation and transfusion of 2 units of blood or more. Univariate analyses and multivariate regression models were applied to identify independent predictors of MAEs after surgical MV repair.

RESULTS

Mean patient age was 57.0 ± 13.2 years, and the majority of patients were men (59.0%, 533/903). The prevalence of preoperative risk factors was as follows: stroke 3.9% (35/903), immunosuppression 2.4% (22/903), heart failure 32.1% (290/903), renal failure 3.5% (32/903), and previous coronary artery bypass grafting 3.4% (31/903). Mean ejection fraction was 55.6 ± 11.3%. MAE rate was 29.0% (262/903), including atrial fibrillation 17.6% (159/903), renal failure 1.3% (12/903), stroke 0.9% (8/903), and operative mortality 1.1% (10/903). Multivariate correlates of MAE included the following: advanced age, prior stroke, immunosuppression, and operation time. Importantly, gender, previous coronary bypass grafting, renal failure, and ejection fraction were not independent predictors of MAE.

CONCLUSIONS

In the current era, patients undergoing surgical MV repair have low mortality. MAE rate was largely due to postoperative atrial fibrillation. These results may help to stratify which patients may be best served with newer technologies.

Repair of Acute Post Infarction Mitral Regurgitation with Papillary Muscle Reimplantation - A case report -

A 53-year-old man presenting with dyspnea and chest pain was diagnosed with acute myocardial infarction secondary to occlusion of the left circumflex coronary artery. Urgent revascularization by percutaneous stenting was successfully performed. However, the post-echocardiography revealed a ruptured papillary muscle that was causing severe mitral regurgitation and aggravation of congestive heart failure. The patient subsequently underwent mitral valve repair with papillary muscle re-implantation. Postoperative echocardiography showed a competent mitral valve without residual stenosis or regurgitation. The patient was discharged from the hospital with an uneventful recovery and has been doing well on outpatient follow up.

The effect of mitral annuloplasty shape in ischemic mitral regurgitation: a finite element simulation

BACKGROUND

Undersized mitral annuloplasty (MA) is the preferred surgical treatment for chronic ischemic mitral regurgitation. However, the preferred shape of undersized MA is unclear.

METHODS

A previously described finite element model of the left ventricle with mitral valve based on magnetic resonance images of a sheep with chronic ischemic mitral regurgitation after posterolateral myocardial infarction was used. Saddle-shape (Edwards Physio II) and asymmetric (IMR ETlogix) MA rings were digitized and meshed. Virtual annuloplasty was performed using virtual sutures to attach the MA ring. Left ventricular diastole and systole were performed before and after virtual MA of each type.

RESULTS

Both types of MA reduced the septolateral dimension of the mitral annulus and abolished mitral regurgitation. The asymmetric MA was associated with lower virtual suture force in the P2 region but higher force in P1 and P3 regions. Although both types of MA reduced fiber stress at the left ventricular base, fiber stress reduction after asymmetric MA was slightly greater. Neither type of MA affected fiber stress at the left ventricular equator or apex. Although both types of MA increased leaflet curvature and reduced leaflet stress, stress reduction with saddle-shape MA was slightly greater. Both MA types reduced stress on the mitral chordae.

CONCLUSIONS

The effects of saddle-shape and asymmetric MA rings are similar. Finite element simulations are a powerful tool that may reduce the need for animal and clinical trials.

Percutanenous therapies for mitral regurgitation

Percutaneous therapies for the treatment of mitral regurgitation have emerged rapidly over the past several years. Most of the percutaneous approaches are modifications of existing surgical approaches to mitral annuloplasty or leaflet repair. Most of the percutaneous devices are based on surgical approaches. Catheter-based leaflet repair with the MitraClip is accomplished using an implantable clip to mimic the surgical edge-to-edge technique. Percutaneous annuloplasty can be achieved indirectly via the coronary sinus, or directly from retrograde left ventricular access. Several of these percutaneous approaches have been successfully used in trials or are in the early stages of use in practice.

Relationship between mitral leaflets angles, left ventricular geometry and mitral deformation indices in patients with ischemic mitral regurgitation: imaging by echocardiography and cardiac magnetic resonance

Chronic ischemic mitral regurgitation (IMR) is associated with a markedly worse prognosis after myocardial infarction (MI).The study aimed to evaluate the relationship between anterior and posterior mitral leaflet angle (MLA) values, left ventricle remodeling and severity of ischaemic mitral regurgitation (IMR).

METHODS

Forty-two patients (age 63.5 ± 9.7 years, 36 men) with chronic IMR (regurgitant volume, RV > 20 ml; >6 months after MI) underwent transthoracic echocardiography (TTE) and cardiovascular magnetic resonance (CMR) imaging. Anterior and posterior MLA, determined by echocardiography, were correlated with indices of LV remodeling, mitral apparatus deformation and IMR severity by CMR. The anterior and posterior MLA was 25.41 ± 4.28 and 38.37 ± 8.89° (mean ± SD). In 5 patients (11.9%) the posterior MLA was ≥45°. There was a significant correlation between anterior MLA and RV (r = 0.74, P = 0.01). For patients with RV > 30 ml this correlation was stronger (r = 0.97, P = 0.005) and, in addition, there was a correlation between the RV and posterior MLA (r = 0.90, P = 0.037), between tenting area and posterior MLA (r = 0.90, P = 0.04), and between tenting area and anterior MLA (r = 0.82, P = 0.08). With regard to LV remodeling parameters, there was weaker but significant correlation between posterior MLA and LV end-diastolic volume index (r = 0.35, P = 0.031), LV end-systolic volume index (r = 0.37, P = 0.021), stroke volume (r = 0.35, P = 0.03), sphericity index (r = 0.33, P = 0.041). Anterior MLA correlated with wall motion score index (r = 0.41, P = 0.019). Besides, there was a correlation between posterior MLA and left atrial volume (r = 0.41, P = 0.012). Measurement of anterior and posterior MLA may play an important role in evaluating patients with IMR.

Percutaneous Techniques for the Treatment of Patients with Functional Mitral Valve Regurgitation

Percutaneous approaches to mitral regurgitation remain largely investigational. In the last decade, novel percutaneous strategies have opened new options in the treatment of valvular heart disease. Several studies are currently underway to determine the benefits of transcatheter mitral valve repair therapy. Transcatheter chordal procedures are being developed, including chordal cutting and chordal implantation. Transcatheter valve implantation in the mitral position might offer a desirable alternative in selected patients and has been accomplished in a compassionate fashion on rare occasions in patients who are not candidates for surgical valve repair or replacement.