Efficacy of Mitral Valve Repair as an Adjunct Procedure to Coronary Artery Bypass Grafting in Moderate Ischemic Mitral Regurgitation: A Meta-Analysis of Randomized Trials

Mitral repair with annuloplasty for moderate ischemic mitral regurgitation in people undergoing coronary artery bypass surgery

OBJECTIVES

This is a protocol for a Cochrane Review (intervention). The objectives are as follows: To assess the effects of mitral repair with annuloplasty for moderate ischemic mitral regurgitation in people undergoing coronary artery bypass grafting.

Efficacy of mitral valve repair in combination with coronary revascularization for moderate ischaemic mitral regurgitation: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

The efficacy of mitral valve repair (MVR) in combination with coronary artery bypass grafting (CABG) for moderate ischaemic mitral regurgitation (IMR) remains unclear. To evaluate whether MVR + CABG is superior to CABG alone, the authors conducted a systematic review and meta-analysis of existing randomized controlled trials (RCTs).

METHODS

The authors searched PubMed, Web of Science, and the Cochrane Central Register of Controlled Trials for eligible RCTs from the date of their inception to October 2023. The primary outcomes were operative (in-hospital or within 30 days) and long-term (≥ 1 year) mortality. The secondary outcomes were postoperative stroke, worsening renal function (WRF), and reoperation for bleeding or tamponade. The authors performed random-effects meta-analyses and reported the results as risk ratios (RRs) with 95% CIs.

RESULTS

Six RCTs were eligible for inclusion. Compared with CABG alone, MVR + CABG did not increase the risk of operative mortality (RR, 1.244; 95% CI, 0.514-3.014); however, it was also not associated with a lower risk of long-term mortality (RR, 0.676; 95% CI, 0.417-1.097). Meanwhile, there was no difference between the two groups in terms of postoperative stroke (RR, 2.425; 95% CI, 0.743-7.915), WRF (RR, 1.257; 95% CI, 0.533-2.964), and reoperation for bleeding or tamponade (RR, 1.667; 95% CI, 0.527-5.270).

CONCLUSIONS

The findings of this meta-analysis suggest that MVR + CABG fails to improve the clinical outcomes of patients with moderate IMR compared to CABG alone.

Outcome of Surgery for Ischemic Mitral Regurgitation Depends on the Type and Timing of the Coronary Revascularization

OBJECTIVE

Long-term outcomes of mitral valve (MV) repair versus MV replacement for ischemic mitral regurgitation (IMR) in patients undergoing either prior (PCR) or concomitant coronary revascularization (CCR) by surgery (CABG) or intervention (PCI) are uncertain.

METHODS AND RESULTS

Of 446 patients receiving MV surgery for IMR between July 2006 and December 2010, 125 patients-87 CCR (69.1%) and 38 PCR (30.9%)-were eligible for inclusion in the study. Survival was higher in CCR versus PCR at long-term follow-up (78.83% vs. 57.9%, p = 0.016). The incidence of MACCE was lower in the CCR compared to PCR at both hospital discharge (34.11% vs. 63.57%, p = 0.003) and at follow-up (34.11% vs. 65.79%, p = 0.0008). Patients receiving CABG or CABG with PCI in PCR had higher mortality risks after MV surgery than CCR patients (X2 = 6.029, p = 0.014 and X2 = 6.466, p = 0.011, respectively). Whereas in the PCR group, MV repair and MV replacement achieved similar survival probability (X2 = 1.551, p = 0.213), MV repair in the CCR group led to improved survival compared to MV replacement (X2 = 3.921, p = 0.048). In MV replacement, LAD-CABG improved survival compared to LAD-PCI (U = 15,000.00, Z = -2.373 p = 0.018), and a substantial impact of arterial IMA-LAD grafting was revealed in the Cox-regression analysis (HR 0.334, CI: 0.113-0.989, p = 0.048) as opposed to venous-LAD grafting (HR 0.588, CI: 0.166-2.078, p = 0.410).

CONCLUSION

Early treatment of IMR concomitant to coronary revascularization enhances long-term survival compared to delayed MV surgery after PCR. MV repair is not superior to MV replacement when performed late after coronary revascularization; however, MV repair leads to better survival than MV replacement when performed concomitantly with CABG with arterial LAD revascularization.

Contemporary Management of Ischemic Mitral Regurgitation at Coronary Artery Bypass Grafting

BACKGROUND

Recent guidelines for the treatment of moderate or severe ischemic mitral regurgitation (IMR) in patients undergoing coronary artery bypass grafting (CABG) have changed. This study assessed the real-world impact of changing guidelines on the management of IMR during CABG over time. We hypothesized that the utilization of mitral valve repair for IMR would decrease over time, whereas mitral valve replacement for severe IMR would increase.

METHODS

Patients undergoing CABG in a statewide collaborative database (2011-2020) were stratified by severity of IMR. Trends in mitral valve repair or replacement were evaluated. To account for differences of the patients, propensity score-matched analyses were used to compare patients with and without mitral intervention.

RESULTS

A total of 11,676 patients met inclusion criteria, including 1355 (11.6%) with moderate IMR and 390 (3.3%) with severe IMR. The proportion of patients undergoing mitral intervention for moderate IMR decreased over time (2011, 17.7%; 2020, 7.5%; P_trend = .001), whereas mitral replacement for severe IMR remained stable (2011, 11.1%; 2020, 13.3%; P_trend = .14). Major morbidity was higher for patients with moderate IMR who underwent mitral intervention (29.1% vs 19.9%; P = .005). In a propensity analysis of 249 well-matched pairs, there was no difference in major morbidity (29.3% with mitral intervention vs 23.7% without; P = .16) or operative mortality (1.2% vs 2.4%; P = .5).

CONCLUSIONS

Consistent with recent guideline updates, patients with moderate IMR were less likely to undergo mitral repair. However, the rate of replacement for severe IMR did not change. Mitral intervention during CABG did not increase operative mortality or morbidity.

[Long-Term Survival of Patients with Ischemic Heart Disease After Surgical Correction of Moderate Ischemic Mitral Regurgitation]

AIM

to assess effect of correction of moderate ischemic mitral regurgitation (IMR) in patients with ischemic cardiomyopathy (IMC) in immediate and remote period.

MATERIALS AND METHODS

We included in a single center prospective study 76 patients with IMC, left ventricular ejection fraction ≤35 %, and moderate IMR. Patients with indications to postinfarction aneurism repair were not included. For randomization we used the method of envelopes. Thirty-eight patients were randomized in the group where coronary artery bypass grafting (CABG) was combined with of mitral valve repair (MVR), and 38 patients in the control group of isolated CABG. Mean age of patients was 57±8 (from 30 to 75 лет) years. For IMR correction we used rigid MEDENG ring. Results. Inhospital mortality was 5.4 % (n=2) after isolated CABG and 10.81 % (n=4) after CABG + MVR. Main cause of death was acute heart failure. One- and 2‑year survival was 84 and 78 %, respectively, after CABG+MVR, and 84 and 71 % after isolated CABG. There was significant difference in three-year survival between groups (hazard ratio [HR] of death 0.457, p=0.04). Five-year survival was 45 and 74 % after isolated CABG and CABG+MVR, respectively (р=0.037). Factors associated with inhospital mortality were pulmonary hypertension (HR 2.177, 95 % confidence interval [CI] 2.299 to 9.831; p=0.043), NYHA class IV chronic heart failure (HR 3.027, 95 % CI 1.605 to 5.707; р=0.001), negative result of stress test echocardiography (HR 0.087, 95 %CI 0.041 to 0.186; р<0.001), atrial fibrillation (HR 4.754, 95 %CI 2.299 to 9.831; р<0.001).

CONCLUSION

Correction of moderate IMR in patients with IMC leads to improvement of parameters of survival in remote period. Five-year survival after isolated CABG was 45 %, while after CABG+MVR - 74 % (р=0.037).

Diagnosis and Management of Ischemic Mitral Regurgitation: Evidence-Based Clinical Decision Making at the Point of Care

Anatomical, functional, and pathophysiologic mechanisms of ischemic mitral regurgitation (IMR) are markedly different from the primary mitral regurgitation. The older and ubiquitous cutoff of EROA (effective regurgitant orifice area) and Rvol (regurgitant volume) for IMR has been reinstated in the new guideline after a brief hiatus. There had always been a lack of good-quality evidence for its introduction for guiding IMR severity in the previous guideline, and we still do not have quality evidences that could justify its reintroduction. Unlike primary MR, IMR is usually associated with reduced ejection fraction. Therefore, it appears unrealistic to keep the similar cutoff for primary MR and IMR. The cutoff of severity can be modified according to projected values of Rvol normalized to ejection fraction and EROA normalized to Rvol. In addition, the treatment outcome in these patients is determined by factors (left ventricular dyssynchrony, annular dilatation, tenting area, tenting height, tenting volume, and myocardial viability) other than the simple grading. In this review article, a series of graph have been constructed from the numerical data derived from the literatures on IMR to depict the relationship between EROA, Rvol, left ventricular end diastolic volume, and ejection fraction in order to obtain a reasonable projection formula for EROA and Rvol. Furthermore, a management algorithm has been proposed for patients with IMR undergoing coronary artery bypass grafting based on echocardiographic predictors that influence the postoperative outcome.

Clinical manifestations, diagnosis, and treatment of ischemic mitral regurgitation: a review

Ischemic mitral regurgitation (IMR) is a frequent complication after acute myocardial infarction (AMI) associated with a worse prognosis. The pathophysiological mechanisms of IMR are not fully understood, but it is known to be a complex process in which ventricular remodelling is the main causal factor. The various imaging techniques in cardiology and echocardiography fundamentally have contributed significantly to clarify the mechanisms that cause and progressively aggravate IMR. At present, different therapeutic options, the most important of which are cardio-surgical, address this problem. Nowadays the improvement in cardiac surgery and transcatheter therapies, have shown a therapeutic advance in IMR management. IMR is a predictor of poor prognosis in patients with heart failure and depressed left ventricular (LV) systolic function. However, it remains controversial whether mitral regurgitation (MR) in these patients is a consequence of dilation and dysfunction of the LV, or whether it contributes to worsening the prognosis of the ventricular dysfunction. Given that echocardiography has a fundamental reference role in the identification, graduation of severity and evaluation of the therapeutics used in the treatment of MR, we are going to focus on it over the rest of the imaging techniques. In contrast to primary MR the benefits of mitral surgery in patients with secondary MR are uncertain. Therefore, we will comment fundamentally on the role of mitral surgery in patients with IMR, with an update of the different surgical interventions available, without forgetting to mention the other therapeutic options currently available.

Meta-Analysis of Usefulness of Concomitant Mitral Valve Repair or Replacement for Moderate Ischemic Mitral Regurgitation With Coronary Artery Bypass Grafting

Moderate ischemic mitral regurgitation (MR) is often present in patients undergoing coronary artery bypass grafting (CABG). However, the clinical benefit of repairing moderate MR during CABG is unproven. We searched multiple databases to identify original studies comparing isolated CABG versus combined CABG and MR surgery (mitral valve surgery with coronary artery bypass grafting [MVCABG]); survival (either early or midterm) was the primary end point. Risk ratio (RR) or standardize mean difference was selected as the effect estimates; survival was compared by pooling hazard ratios. All results are presented with 95% CIs; p <0.05 is statistically significant. Eleven studies (7 retrospective and 4 randomized controlled trials; 547 MVCABG and 900 CABG patients) were included in our meta-analysis. Concomitant mitral valve repair significantly prolonged surgical duration (p <0.01). Early mortality (MVCABG 6.9% and CABG 6%) was comparable (RR 1.3 [0.9 to 1.8]; p = 0.11). At follow-up, the MVCABG patients had similar New York Heart Association class (standardize mean difference -0.73 (-1.64 to 0.18; p = 0.11). However, patients who underwent concomitant mitral valve surgery had less MR at follow-up (recurrent significant MR, RR 0.37 [0.22 to 0.62]; p = 0.001; mean MR grade, mean difference = 0.39 [0.26 to 0.59]; p <0.001). Midterm survival rate (mean follow-up 5 years) was comparable in both groups (hazard ratio for mortality in the MVCABG cohort 1.1 [0.9 to 1.3]; p = 0.38). In conclusion, concomitant repair of moderate ischemic MR leads to improved mitral valve competence at follow-up; however, this was not translated into any functional or survival benefit for adding valve repair to CABG for these patients at 5 years of follow-up.

Meta-analysis of concomitant mitral valve repair and coronary artery bypass surgery versus isolated coronary artery bypass surgery in patients with moderate ischaemic mitral regurgitation

Ischaemic mitral regurgitation (IMR) is a complication of coronary artery disease with normal chordal and leaflet morphology. Controversy surrounds the issue of appropriate surgical management of moderate IMR. With the present meta-analysis, we aimed to determine whether the addition of mitral valve (MV) repair to coronary artery bypass grafting (CABG) improved clinical outcome over CABG alone in patients with moderate IMR. Databases were searched for studies reporting on clinical outcomes after CABG and MV repair or CABG alone for moderate IMR. Clinical end-points were operative mortality, survival, New York Heart Association (NYHA) class ≥2 and MR grade ≥2 at last follow-up. A total of five observational and four randomized controlled trials (RCTs) were identified. The mean follow-up was 2.7 years. An analysis of all studies revealed increased operative risk in the concomitant CABG and MV repair group {risk ratio [RR] 2.02 [95% confidence interval (CI) 1.15, 3.56], P = 0.01, I(2) = 0%}. However, an analysis of RCTs only showed that the operative risk was equivalent [RR 1.05 (95% CI 0.34, 3.30), P = 0.93, I(2) = 0%]. Pooled hazard ratio (HR) on survival did not favour either procedure [all studies: HR 1.08 (95% CI 0.77, 1.50), P = 0.66, I(2) = 0%; RCTs only: HR 0.89 (95% CI 0.47, 1.70), P = 0.73, I(2) = 0%]. The incidence of exercise intolerance quantified as NYHA class ≥2 was similar between groups (all studies: RR 0.72 (95% CI 0.42, 1.24), P = 0.24, I(2) = 77%; RCTs only: RR 0.61 (95% CI 0.24, 1.55), P = 0.30, I(2) = 83%]. Risk of residual MR grade ≥2 was higher in the CABG only group [all studies: RR 0.30 (95% CI 0.16, 0.60), P < 0.001, I(2) = 83%; RCTs only: RR 0.20 (95% CI 0.04, 0.90), P = 0.04, I(2) = 72%]. There is neither increased operative mortality nor survival benefit associated with concomitant CABG and MV repair for IMR of moderate degree over CABG alone. Further studies with long-term follow-up data and sub-group analyses of current data are needed to define a subset of patients whose survival and functional status may improve with the concomitant MV repair.

Regurgitation Hemodynamics Alone Cause Mitral Valve Remodeling Characteristic of Clinical Disease States In Vitro

Mitral valve regurgitation is a challenging clinical condition that is frequent, highly varied, and poorly understood. While the causes of mitral regurgitation are multifactorial, how the hemodynamics of regurgitation impact valve tissue remodeling is an understudied phenomenon. We employed a pseudo-physiological flow loop capable of long-term organ culture to investigate the early progression of remodeling in living mitral valves placed in conditions resembling mitral valve prolapse (MVP) and functional mitral regurgitation (FMR). Valve geometry was altered to mimic the hemodynamics of controls (no changes from native geometry), MVP (5 mm displacement of papillary muscles towards the annulus), and FMR (5 mm apical, 5 mm lateral papillary muscle displacement, 65% larger annular area). Flow measurements ensured moderate regurgitant fraction for regurgitation groups. After 1-week culture, valve tissues underwent mechanical and compositional analysis. MVP conditioned tissues were less stiff, weaker, and had elevated collagen III and glycosaminoglycans. FMR conditioned tissues were stiffer, more brittle, less extensible, and had more collagen synthesis, remodeling, and crosslinking related enzymes and proteoglycans, including decorin, matrix metalloproteinase-1, and lysyl oxidase. These models replicate clinical findings of MVP (myxomatous remodeling) and FMR (fibrotic remodeling), indicating that valve cells remodel extracellular matrix in response to altered mechanical homeostasis resulting from disease hemodynamics.