Clinical anatomy of the coronary venous system and relevance to retrograde cardioplegia and cardiac electrophysiological interventions.

Anomalies of coronary venous system, the valve of the coronary sinus (Thebesian valve) and other cardiac malformations may make interventions through the coronary sinus difficult. These variants may pose a challenge in cannulating the coronary sinus for retrograde cardioplegia and for interventions performed through the coronary sinus by cardiac electrophysiologist/interventional cardiologist. Retrograde cardioplegia is an established method of myocardial protection with advantages, indications, and complications. A good knowledge of the anatomy of the coronary sinus and its variants is important in understanding the difficulties encountered while cannulating the coronary sinus for the delivery of retrograde cardioplegia, cardiac resynchronization therapy, treatment of arrhythmias, and percutaneous mitral valve annuloplasty.

Comparison of quality of life in patients with mitral valve replacement and mitral valve repair in Imam Ali Hospital during 2014 to 2020: a cross-sectional study.

OBJECTIVE: Mitral valve failure is one of the most common valvular heart diseases worldwide. Valve replacement and repair have an impact on the quality of life of patients. Therefore, the present study was conducted to compare the quality of life in patients with mitral valve replacement and those who underwent mitral valve repair. METHODS: In this cross-sectional study, we considered all cardiac patients with ischemic mitral insufficiency who underwent mitral valve repair and patients with a history of valve replacement in Imam Ali Hospital of Kermanshah between 2014 and 2020. Two Minnesota and general quality of life questionnaires along with a checklist for demographic variables were used for data collection. Data analysis was performed using SPSS version 21 software. RESULTS: The mean quality of life score based on the general quality of life scale in the valve repair group was 32.33 (SD = 2.29) and in the valve replacement group 32.89(SD = 2.60), (p = 0.917). Also, mean quality of life, as measured by the Minnesota MLHFQ was 60.89(SD = 17.67) in the valve repair group and 63.42 (SD = 12.13) in the valve replacement group (p = 0.308). The results showed that the average general quality of life was different in study groups regarding education. Tukey's post hoc test showed that the average general quality of life in illiterate people is significantly lower than in people with academic degrees (P-value = 0.001). CONCLUSION: The quality of life of the patients in both the valve repair and replacement groups was at an average level. There was no significant difference between the general quality of life and the Minnesota scales, suggesting that both tools can be effectively used to measure patients' quality of life. The study's findings can be valuable for monitoring patients, screening for conditions, and enhancing communication between doctors and patients.

Infant Barlow's Disease in Association with Atrial Septal Defect.

CLINICAL DATA: Female, seven years old, referred to our service complaining about congestive heart failure symptoms due to mitral valve regurgitation and atrial septal defect. Technical description: Echocardiographic findings compatible with Barlow's disease and atrial septal defect, ostium secundum type. OPERATION: She was submitted to mitral valvuloplasty with chordal shortening and prosthetic posterior ring (Gregori-Braile®) along with patch atrioseptoplasty. COMMENTS: Mitral valve regurgitation is a rare congenital heart disease and Barlow's disease is probably rarer. Mitral valve repair is the treatment of choice.

Mitral Valve Surgery for Mitral Regurgitation Results in Reduced Left Ventricular Ejection Fraction in Barlow's Disease as Compared with Fibro-Elastic Deficiency.

Surgical correction of severe mitral regurgitation (MR) can reverse left ventricular (LV) remodeling in patients with mitral valve prolapse (MVP). However, whether this process is similar to the case in Barlow's Disease (BD) and Fibro-elastic Deficiency (FED) is currently unknown. The aim of this study is to evaluate post-operative LV reverse remodeling and function in patients with BD versus FED. In this study, 100 MVP patients (BD = 37 and FED = 63) with severe MR who underwent mitral valve surgery at three Belgian centers were retrospectively included. Transthoracic echocardiography was used to assess MR severity, LV volumes and function before surgery and 6 months thereafter. Baseline MR severity, LV ejection fraction (LVEF), indexed LV end-diastolic (LVEDVi) and end-systolic volumes (LVESVi) were not different between the groups. After a median follow-up of 278 days, there was a similar decrease in LVEDVi, but a trend towards a smaller decrease in LVESVi in BD compared to FED (-3.0 ± 11.2 mL/m2 vs. -5.3 ± 9.0 mL/m2; p = 0.154). This resulted in a significantly larger decrease in LVEF in BD (-8.3 ± 9.6%) versus FED (-3.9 ± 6.9%) after adjusting for baseline LVEF (p < 0.001) and type of surgical intervention (p = 0.01). These findings suggest that LV (reverse) remodeling in BD could be affected by other mechanisms beyond volume overload, potentially involving concomitant cardiomyopathy.

Respect Versus Resect Approaches for Mitral Valve Repair: A Meta-Analysis of Reconstructed Time-to-Event Data.

Mitral valve repair (MVr) has been associated with superior long-term survival and freedom from valve-related complications compared with mitral valve replacement for primary mitral regurgitation (MR). The 2 main approaches for MVr are chordal replacement ("respect approach") and leaflet resection ("resect approach"). We performed a systematic review and a meta-analysis using 3 search databases to compare the long-term end points between both approaches. The primary end point was long-term survival. The secondary end points were long-term MR recurrence and reoperation. After reconstruction of time-to-event data for the individual survival analysis, pooled Kaplan-Meier curves for the end points were generated. A total of 14 studies (5,565 patients) were included in the analysis. The respect approach was associated with superior survival compared with the resect approach in the overall sample (hazard ratio [HR] 0.73, 95% confidence interval [CI] 0.56 to 0.96, p = 0.024, n = 3,901 patients) but not in the risk-adjusted sample (HR 1.00, 95% CI 0.55 to 1.82, p = 0.991, n = 620 patients). There was no difference between the approaches in the rate of MR recurrence in the overall sample (HR 1.39, 95% CI 0.92 to 2.08, p = 0.116, n = 1,882 patients) or in the risk-adjusted sample (HR 1.62, 95% CI 0.76 to 3.47, p = 0.211, n = 288 patients). The data for reoperation were only available in the overall sample and did not reveal a difference (HR 0.92, 95% CI 0.62 to 1.35, p = 0.663, n = 3,505 patients). In conclusion, the current evidence suggests no difference in long-term mortality, MR recurrence, or reoperation between the resect and respect approaches for MVr after adjusting for patient risk factors. More long-term follow-up data are warranted.

Infant Barlow's Disease in Association with Atrial Septal Defect

ABSTRACT Clinical data: Female, seven years old, referred to our service complaining about congestive heart failure symptoms due to mitral valve regurgitation and atrial septal defect. Technical description: Echocardiographic findings compatible with Barlow's disease and atrial septal defect, ostium secundum type. Operation: She was submitted to mitral valvuloplasty with chordal shortening and prosthetic posterior ring (Gregori-Braile®) along with patch atrioseptoplasty. Comments: Mitral valve regurgitation is a rare congenital heart disease and Barlow's disease is probably rarer. Mitral valve repair is the treatment of choice.

Transcatheter Mitral Valve Replacement in Patients with Mitral Annular Calcification: A Review.

Mitral annular calcification (MAC) is a progressive degenerative calcification of the mitral valve (MV) that is associated with mitral stenosis, regurgitation or both. Patients with MAC are poor candidates for MV surgery because of technical challenges and high peri-operative mortality. Transcatheter MV replacement (TMVR) has emerged as an option for such high surgical risk patients. This has been described with the use of the SAPIEN transcatheter heart valve (valve-in-MAC) and dedicated TMVR devices. Careful anatomic assessment is important to avoid complications of TMVR, such as left ventricular outflow tract obstruction, valve migration, embolization and paravalvular mitral regurgitation. In this review, we discuss the pathology, importance of preprocedural multimodality imaging for optimal patient selection, clinical outcomes and complications associated with TMVR in patients with MAC.

Long-term outcomes of concomitant suture bicuspidization technique to treat mild or moderate tricuspid regurgitation in patients undergoing mitral valve surgery.

OBJECTIVES: The aim of this study was to investigate the long-term outcomes of concomitant suture bicuspidization to treat mild or moderate tricuspid regurgitation at the time of mitral valve (MV) surgery. METHODS: Data from patients who underwent MV surgery for degenerative MV regurgitation with mild or moderate tricuspid regurgitation and annular dilatation between January 2009 and December 2017 were analysed. The cohort was divided into 2 groups: mitral valve surgery alone (MVA) and MV surgery with concomitant tricuspid valve (TV) repair. RESULTS: A total of 196 patients were included in the study. MVA and MV surgery with concomitant TV repair were performed in 91 (46.4%) and 105 (53.6%) patients, respectively. Propensity score matching analysis identified 54 pairs. In the matched cohort, 30-day mortality (0.0% vs 1.9%, P = 1.0) and new permanent pacemaker implantation (11.1% vs 7.4%, P = 0.740) did not differ significantly between groups. After a mean follow-up of 6.0 (2.8) years, MV surgery with concomitant TV repair was not associated with increased mortality risk compared to MVA (hazard ratio 1.04, 95% confidence interval 0.47-2.28, P = 0.927) with 10-year overall survival rates of 69.9% and 77.2%, respectively. Furthermore, MV surgery with concomitant TV repair was associated with a significantly reduced progression of TV regurgitation (P < 0.001). CONCLUSIONS: Patients undergoing MV surgery with concomitant TV repair had similar 30-day and long-term survival, similar permanent pacemaker implantation rate and reduced progression of TV regurgitation compared to those undergoing MVA.

Respect versus resect approaches for mitral valve repair: A study-level meta-analysis.

Mitral valve repair (MVr) restores leaflets coaptation while preserving the patient's own valve. The two main techniques are: (a) chordal replacement ("respect approach"), whereby artificial neochordae are used to resuspend prolapsed segments of the affected leaflet - and (b) leaflet resection ("resect approach"), whereby diseased leaflet segment is resected, and the remaining segments are sutured together. Both techniques of MVr are associated with better long-term results, fewer valve-related complications and lower mortality when compared with mitral valve replacement (MVR). They also restore quality of life and improve survival to rates equivalent to those of the general population. We performed a meta-analysis to pool data of clinical studies that compared outcomes of MVr stratified by the surgical technique. Seventeen studies accounting for 6,046 patients fulfilled our eligibility criteria. The "respect approach" outperformed the "resect approach" with lower permanent pacemaker implantation rates and lower mean gradients. Despite any possible advantages of one technique over the other, which approach is best for each patient must be decided on a case-by-case basis and more long-term follow-up data are warranted.

Short-Term Results on Leaflet Mobility in Patients Undergoing Rheumatic Mitral Valve Repair With an Efficient 4-Step Commissuroplasty Technique.

BACKGROUND: Mitral valve stenosis (MS) is the primary pathologic feature of rheumatic mitral valve disease, and the complex repair affects its clinical outcome. This study aimed to examine the efficacy of the 4-step commisuroplasty "SCORe" procedure by assessing changes in the mobility of mitral valve leaflets and its clinical effects. METHODS: From September 1, 2018, to January 13, 2019, patients with MS who underwent mitral valve repair with the SCORe procedure in the study center were analyzed in this prospective study. Mitral valve structure was assessed by transthoracic echocardiography pre- and postoperatively as well as during follow-up. RESULTS: In total, 60 consecutive patients were examined. In 56 patients (93.3%), mitral valve orifice area (MVOA) was less than 1.5 cm2, and mean (SD) MVOA for the whole cohort was 1.20 (0.34) cm2. The mobility of the anterior leaflet was improved (P < .001) during the cardiac cycle postsurgery, but that of the posterior leaflet was not (P = .591). The mean (SD) coaptation length was increased significantly from 6.69 (1.32) mm to 7.92 (1.24) mm (P < .001) postoperatively. Mean (SD) MVOAs increased to 2.24 (0.38) cm2 postoperatively (P < .001). During the 1-year follow-up, there were no deaths or reoperations. Follow-up echocardiography revealed minor or mild regurgitation in 98.3% of patients. CONCLUSION: These findings demonstrated that the SCORe procedure can effectively improve the mobility of mitral leaflets and enlarge the valve orifice area in patients with rheumatic MS in China, with minimal complications and promising results.

Anatomy and Topography of Coronary Sinus and Mitral Valve Annulus in Functional Mitral Regurgitation.

Background: We aimed to investigate the anatomical relationship of the coronary sinus (CS) and the mitral valve annulus (MVA) in patients with or without functional mitral regurgitation (FMR) using a multislice CT (MSCT) software to determine (a) the distance and angle of both CS and MVA plane and (b) the mitral annulus geometry. Methods: A total of 215 patients with MSCT and CS to MVA topography evaluation were enrolled in this retrospective study. Results: This patient cohort included 145 patients without FMR (67.4%, FMR ≤ 1+) and 70 patients (32.6%) with clinically relevant FMR (FMR ≥ 2+). Distance and angulation of CS to MVA planes were highly variable. In all groups, no significant correlation was documented between the distance or angle of CS to MVA planes and left ventricular ejection fraction, left ventricular end-diastolic diameter, or left atrial volume. A significant increase in total CS length could be found in patients with FMR ≥ 2+ compared to the FMR ≤ 1+ group. MVA diameter, area, and perimeter were significantly increased in FMR ≥ 2+ compared to FMR ≤ 1+. In the FMR ≥ 2+ cohort 61% showed a distance of CS to MVA plane <7.8 mm and 58% revealed an angle of CS to MVA plane <14.2°. Conclusion: Distance and angulation of CS to MVA topography using an MSCT approach are similar between patients with or without FMR, while CS length, MVA area, MVA perimeter, anterior-posterior diameter, and intercommissural diameter are significantly increased in all FMR subgroups. However, ~60% of FMR ≥ 2+ patients showed favorable CS to MVA topography for indirect mitral annuloplasty.

Early- and Long-Term Outcomes of Mitral Valve Repair in a Low-Volume Centre in the Caribbean

Abstract Introduction: This study examines early- and long-term outcomes of mitral valve repairs in a low-volume cardiac surgery centre in the Caribbean. Methods: Ninety-six consecutive patients underwent mitral valve repair from April 2009 to December 2018. Patients were divided into two groups: functional mitral regurgitation requiring simple mitral annuloplasty (FMR, n=63) or structural degenerative mitral regurgitation requiring more complex repair (DMR, n=33). Data collected prospectively were retrospectively analysed from the unit-maintained cardiac surgery database. Results: Thirty-day mortality in the whole series was 2.1%, with 3% in the FMR group and 0% in the DMR group. Early post-operative echocardiography in the FMR group demonstrated 51 patients (83.6%) without mitral regurgitation, 8 patients (13.1%) with trivial to mild regurgitation, and 2 patients (3.3%) with moderate regurgitation. However, at a mean follow-up of 98.2±50.8, only 21 patients (42.8%) were in NYHA class I, with 7 (14.2%) in class II, 16 (32.6%) in class III, and 5 (10.2%) in class IV. There were 9 cardiac-related deaths at final follow-up, with freedom from re-operation and survival of 98% and 75.6%, respectively. In the DMR group, early post-operative echocardiography demonstrated 29 patients (87.9%) without mitral regurgitation, 3 patients (9.1%) with trivial regurgitation and 1 patient (3.0%) with mild regurgitation. At a mean follow-up of 114.1±25.4 months, there was a good functional post-operative status in this group with 93.3% in NYHA class I, and 6.7% in class II. No patient required reintervention, 96.3% of patients had mild or no mitral regurgitation and survival was 90.9%. Conclusion: Despite challenges of maintaining skills in a low-volume centre, mitral valve repair can be performed safely with good early- and long-term results.

[Transcatheter mitral valve replacement : Indications, options, and techniques as well as important aspects for perioperative care]. / Interventioneller Mitralklappenersatz : Indikationen, Möglichkeiten und Technik sowie wichtige Aspekte für die perioperative Betreuung.

Transcatheter therapy of the mitral valve is more challenging compared to the aortic valve. Interventional therapy with the Mitra-Clip system, mimicking the surgical edge-to-edge repair, was first introduced in 2003 and received the CE mark in 2008. The first implantation of the Tendyne system, which is currently the only commercially available system for mitral valve replacement, was performed in 2014, and routine clinical use was approved in 2020. Several new valve platforms are in clinical development and will expand the treatment portfolio. This article will discuss the clinical indications, technical challenges and specific requirements for perioperative management.

Early- and Long-Term Outcomes of Mitral Valve Repair in a Low-Volume Centre in the Caribbean.

INTRODUCTION: This study examines early- and long-term outcomes of mitral valve repairs in a low-volume cardiac surgery centre in the Caribbean. METHODS: Ninety-six consecutive patients underwent mitral valve repair from April 2009 to December 2018. Patients were divided into two groups: functional mitral regurgitation requiring simple mitral annuloplasty (FMR, n=63) or structural degenerative mitral regurgitation requiring more complex repair (DMR, n=33). Data collected prospectively were retrospectively analysed from the unit-maintained cardiac surgery database. RESULTS: Thirty-day mortality in the whole series was 2.1%, with 3% in the FMR group and 0% in the DMR group. Early post-operative echocardiography in the FMR group demonstrated 51 patients (83.6%) without mitral regurgitation, 8 patients (13.1%) with trivial to mild regurgitation, and 2 patients (3.3%) with moderate regurgitation. However, at a mean follow-up of 98.2±50.8, only 21 patients (42.8%) were in NYHA class I, with 7 (14.2%) in class II, 16 (32.6%) in class III, and 5 (10.2%) in class IV. There were 9 cardiac-related deaths at final follow-up, with freedom from re-operation and survival of 98% and 75.6%, respectively. In the DMR group, early post-operative echocardiography demonstrated 29 patients (87.9%) without mitral regurgitation, 3 patients (9.1%) with trivial regurgitation and 1 patient (3.0%) with mild regurgitation. At a mean follow-up of 114.1±25.4 months, there was a good functional post-operative status in this group with 93.3% in NYHA class I, and 6.7% in class II. No patient required reintervention, 96.3% of patients had mild or no mitral regurgitation and survival was 90.9%. CONCLUSION: Despite challenges of maintaining skills in a low-volume centre, mitral valve repair can be performed safely with good early- and long-term results.

Percutaneous Coronary Sinus-Based Mitral Valve Repair Differentially Modulates Coronary Sinus to Mitral Valve Annulus Geometry and Topography.

Objectives: Coronary sinus (CS) based mitral annuloplasty using the Carillon device is a therapeutic option for the treatment of functional mitral valve regurgitation (FMR). Background: Little is known about the change of CS and mitral valve annulus (MVA) planes following Carillon implantation and how they are modulated by the tension applied on the device. Methods: In a retrospective single-center analysis, 10 patients underwent Carillon device implantation and received CT-angiography (CTA) prior and post CS based percutaneous mitral valve repair. Patients were assigned to responders or non-responders according to the 3-month transthoracic echocardiographic follow-up. A prototype software was used to assess distance and angulation of both CS (pre) or Carillon-device (post) and mitral annulus planes. Results: Comparison of the distance and angulation of the CS plane or Carillon device plane and the MVA plane prior and post intervention showed significant reduction of distance and unchanged angulation in responders while angulation was increased and distance reduced in non-responders without statistical significance. Furthermore, in FMR responders MVA perimeter, anterior-posterior diameter, intercommisural diameter and MVA area were decreased following successful indirect mitral valve annuloplasty, while in FMR non-responders Carillon device implantation had no effect on MVA geometry. Conclusions: Insufficient reduction of FMR following indirect mitral valve annuloplasty is associated with device malposition in relation to the mitral valve annulus. Patient selection using CTA-derived distance and angulation of CS to MVA planes is one option to increase effectiveness of indirect mitral valve annuloplasty.

Valvuloplasty Without Prosthetic Ring or Band in Patients with Degenerative Mitral Regurgitation: Long-Term Results and Predictive Factors for Outcomes

Abstract Introduction: Mitral valvuloplasty including ring/band support is widely performed despite potential drawbacks of rings. Unsupported valvuloplasty is performed in only a few centers. This study aimed to report long-term outcomes of patients undergoing unsupported valvuloplasty for degenerative mitral regurgitation (MR) and to identify predictive factors for outcomes. Methods: This is a retrospective cohort including patients undergoing mitral valve repair for degenerative MR from 2000 to 2018. The main techniques were Wooler annuloplasty and quadrangular resection. Kaplan-Meier curves and Cox regression models were used for statistical analysis. Results: One hundred fifty-eight patients were included (median age: 64.0 years). In-hospital mortality was 2.5%. Maximum follow-up was 19.6 years, with a median of 4.7 years (992 patient-years). Overall survival at 5, 10, and 15 years was 91.0% (95% confidence interval [CI]: 85.7-96.3), 87.6% (95% CI: 80.7-94.5), and 78.1% (95% CI: 65.9-90.3), respectively. The European System for Cardiac Operative Risk Evaluation (EuroSCORE) II was an independent predictor of late death (hazard ratio [HR] 1.42; P=0.016). Freedom from mitral reoperation at 5, 10, and 15 years was 88.1% (95% CI: 82.0-94.2), 82.4% (95% CI: 74.6-90.2), and 75.7% (95% CI: 64.1-87.3), respectively. Left atrial diameter > 56 mm was associated with late reintervention in univariate analysis (HR 1.06; P=0.049). Conclusion: Degenerative MR can be successfully treated with repair techniques without annular support, thus avoiding the technical and logistical drawbacks of ring/band implantation while maintaining good long-term results. EuroSCORE II was a risk factor for late death, and larger left atrium was associated with late reoperation.

Valvuloplasty Without Prosthetic Ring or Band in Patients with Degenerative Mitral Regurgitation: Long-Term Results and Predictive Factors for Outcomes.

INTRODUCTION: Mitral valvuloplasty including ring/band support is widely performed despite potential drawbacks of rings. Unsupported valvuloplasty is performed in only a few centers. This study aimed to report long-term outcomes of patients undergoing unsupported valvuloplasty for degenerative mitral regurgitation (MR) and to identify predictive factors for outcomes. METHODS: This is a retrospective cohort including patients undergoing mitral valve repair for degenerative MR from 2000 to 2018. The main techniques were Wooler annuloplasty and quadrangular resection. Kaplan-Meier curves and Cox regression models were used for statistical analysis. RESULTS: One hundred fifty-eight patients were included (median age: 64.0 years). In-hospital mortality was 2.5%. Maximum followup was 19.6 years, with a median of 4.7 years (992 patient-years). Overall survival at 5, 10, and 15 years was 91.0% (95% confidence interval [CI]: 85.7-96.3), 87.6% (95% CI: 80.7-94.5), and 78.1% (95% CI: 65.9-90.3), respectively. The European System for Cardiac Operative Risk Evaluation (EuroSCORE) II was an independent predictor of late death (hazard ratio [HR] 1.42; P=0.016). Freedom from mitral reoperation at 5, 10, and 15 years was 88.1% (95% CI: 82.0-94.2), 82.4% (95% CI: 74.6-90.2), and 75.7% (95% CI: 64.1-87.3), respectively. Left atrial diameter > 56 mm was associated with late reintervention in univariate analysis (HR 1.06; P=0.049). CONCLUSION: Degenerative MR can be successfully treated with repair techniques without annular support, thus avoiding the technical and logistical drawbacks of ring/band implantation while maintaining good long-term results. EuroSCORE II was a risk factor for late death, and larger left atrium was associated with late reoperation.

Multicenter experience: early outcome of mitral valve repair in patients with ischemic mitral regurgitation.

BACKGROUND: Ischemic mitral regurgitation is associated with poor outcomes. The optimal surgical strategy for management of ischemic mitral regurgitation is still debated. The objective of this study was to evaluate the early mortality and morbidity of mitral valve repair in patients with ischemic mitral regurgitation undergoing coronary artery bypass grafting. METHODS: We performed a retrospective, observational, cohort study on prospectively collected data on 136 consecutive coronary artery bypass graft patients with ischemic mitral regurgitation undergoing mitral valve repair between January 2016 and January 2020. Perioperative echocardiogram findings, operative procedures, and outcomes were analyzed. RESULTS: The overall mortality rate was 4.4%. Mitral valve repair with a low ejection fraction had a 4-fold increase in the risk of death compared to mitral valve repair with preserved ejection fraction > 30%. However, after adjusting for preoperative risk factors, the number of grafts was not an independent risk factor for mortality (odds ratio = 0.18, 95% confidence interval: 0.03-2.81, p = 0.84). Multivariable analysis showed that preoperative ejection fraction (odds ratio = 1.14, 95% confidence interval: 0.82-4.86, p < 0.01), preoperative left ventricular end-systolic dimension (odds ratio = 1.03, 95% confidence interval: 0.65-3.51, p < 0.01) and preoperative left ventricular end-diastolic dimension (odds ratio = 0.99, 95% confidence interval: 0.64-3.28, p = 0.04) were independent risk factors for mortality. CONCLUSIONS: Mitral valve repair can be performed safely concomitantly with coronary artery bypass grafting in patients with moderate, moderately severe, and severe ischemic mitral regurgitation.