ARTICLE IN PRESS doi:10.1510/icvts.2007.157891
Interactive CardioVascular and Thoracic Surgery 6 (2007) 538–546 www.icvts.org
Best evidence topic - Cardiac general
Should patients undergoing coronary artery bypass grafting with mild to moderate ischaemic mitral regurgitation also undergo mitral valve repair or replacement? Aseem Ranjan Srivastavaa, Amit Banerjeea, Samuel Jacobb, Joel Dunningc,* Department of Cardiothoracic and Vascular Surgery, G B Pant Hospital, New Delhi, India b Department of Cardiothoracic Surgery, Aberdeen Royal Infirmary, Aberdeen, UK c Department of Cardiothoracic Surgery, James Cook University Hospital, Middlesbrough, UK a
Received 16 April 2007; received in revised form 23 April 2007; accepted 26 April 2007
Summary A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether mitral valve repair at the time of coronary artery bypass grafting (CABG) in patients with coronary artery disease and mild to moderate mitral insufficiency improves short and long-term outcome. Altogether 465 papers were found using the reported search, of which 16 presented the best evidence to answer the clinical question. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results, and study weaknesses of these papers are tabulated. We conclude that there is good evidence to suggest that moderate mitral regurgitation in patients undergoing isolated CABG adversely affects survival and mitral regurgitation does not reliably improve after CABG alone. Unfortunately, the evidence to support mitral valve repair at the time of CABG to improve long-term survival is still weak. On balance, patients with moderate ischaemic mitral regurgitation having CABG should have mitral repair at the same time, although the evidence to support this is weaker than one might like. 䊚 2007 Published by European Association for Cardio-Thoracic Surgery. All rights reserved. Keywords: Mitral valve insufficiency; Myocardial revascularization; Mitral repair; Coronary artery bypass graft
1. Introduction
4. Search strategy
A best evidence topic was constructed according to a structured protocol. This protocol is fully described in the ICTVS w1x.
Medline 1950–April 2007 using the OVID interface. wexp mitral valve insufficiencyyOR mitral regurgitation OR mitral valve regurgitation.mp OR mitral incompetence.mp OR mitral valve incompetence.mp OR mitral valve insufficiency.mp OR mitral insufficiency.mpx AND wexp Myocardial revascularizationyOR revascularization.mp OR exp coronary artery bypassyOR CABG.mp OR Coronary art$ bypass.mpx AND woutcome.mp or exp Treatment outcomeyOR exp survivalyOR survival.mp OR Ventricular Dysfunction,LeftyOR ejection fraction.mp OR Ventricular failure.mpx
2. Clinical scenario You are planning coronary artery bypass grafting on a 55-year-old patient with two myocardial infarctions in the past and severe triple vessel disease on angiography. His ejection fraction is 40%. He also has moderate ischaemic mitral insufficiency on echocardiography. It is your usual practice to just perform the bypass grafting, assuming that the myocardial function will improve and the mitral insufficiency will resolve. However, a cardiologist tells you that, in his experience, they always do better if the mitral valve is repaired and the mitral regurgitation often does not improve if this is not done. You resolve to look up this topic in the literature.
5. Search outcome Four hundred and sixty-five papers were found in Medline. From these 16 were deemed to be relevant and were reviewed in full. These are summarized in Table 1. 6. Results
3. Three-part question In (patients undergoing coronary artery bypass grafting) does (repair of mild to moderate ischemic mitral insufficiency) improve (survival or functional status). *Corresponding author. Tel.yfax: q44-780-1548122. E-mail address:
[email protected] (J. Dunning). 䊚 2007 Published by European Association for Cardio-Thoracic Surgery
Mild and moderate mitral regurgitation (MR) is a common coexisting problem in patients undergoing CABG with reported incidence of 28.2% w8x to 50.7% w2x for mild MR, and 4.0% w8x to 11.8% w2x for moderate MR. However, optimal management of these patients remains controversial. Recent data w5, 9, 12x contest the previous notion that
ARTICLE IN PRESS A.R. Srivastava et al. / Interactive CardioVascular and Thoracic Surgery 6 (2007) 538–546
539
Table 1 Best evidence papers Author, country, and date Study type (level of evidence)
Patient group
Outcomes
Key results
Comments
Grossi et al., 2006, Circulation, USA w2x
1996–2004, 2242 patients undergoing isolated CABG, 841 (37.4%) no MR, 1137 (50.7%) had mild MR, 264 (11.8%) with moderate MR. Co morbidities (diabetes, COPD, multivessel disease) did not significantly differ
Hospital mortality
Hospital mortality: RR 2.2 for moderate MR, 0.9 for mild and 0.8 for no MR (P-0.001)
Independent of ventricular dysfunction, both mild and moderate MR are associated with decreased survival
Survival: Overall: 84"1.0%, No MR: 86"1.0% Mild MR: 84"1.0%, Mod. MR: 70"1.0% (P-0.001)
All patients underwent isolated CABG, effect of mitral valve repair on survival not explored
Retrospective cohort study (level 2b)
5-year all cause mortality Survival
Mod. MR (P-0.007) and mild MR (P-0.033) independently associated with decreased survival
Grading of MR based on TEE done under GA- (in functional insufficiencies, changes in blood volumes secondary to vascular tone under GA can reduce the degree of regurgitation) The groups had similar incidence of diabetes, COPD, multivessel disease, however, patients with moderate MR were older, with more renal disease, previous MI, CHF, previous cardiac surgery, lower EF
Kang et al., 2006, Circulation, Korea w3x Prospective case control study (level 3b)
1997–2003, 107 patients with moderate to severe ischemic MR. CABG only in 57 and CABGqMV repair in 50 Mean follow-up: 40"25 months
Operative mortality
In-hospital deaths: 6 (12%) in repair groups vs. 1 (2%) in CABG group (Ps0.03) (4y7 in-hospital deaths non cardiac-MOFS, Mediastinitis, Ticlopidine induced pancytopenia, aspiration pneumonia)
Estimated actuarial 1- and 5-year survival rates
Severity of MR did not affect operative mortality and long-term survival. Estimated 1- and 5-year actuarial survival similar in both groups Subgroup analysis of patients with moderate MR: 2y14 (14%) in-hospital deaths and no late deaths in repair group vs. no in-hospital deaths and 2y33 (6%) late deaths in CABG group. Operative mortality higher (Ps0.03) in patients undergoing repair
Change in NYHA class
Similar improvement in NYHA class in both groups
Change in severity of MR
Improvement rates in severity of MR in patients with moderate MR similar between the 2 groups (75% vs. 67%)
In patients with moderate MR, operative mortality is higher with CABGqMV repair whereas MR improvement rates are similar Selection criteria for concomitant annuloplasty not standardised and based on surgeons discretion only CABGqMV repair group had significantly more patients with severe MR (72% vs. 42%) Mortality in subgroup of patients with moderate MR undergoing isolated CABG vs. CABGqMV repair too small to permit reliable subgroup analysis 2 w(14%) operative deaths in CABGqMVR vs. 2 late deaths in isolated CABGx No sample size calculations
Ogus et al., 2004, Tex Heart I J, Turkey w4x
Prospective observational cohort study (level 2b)
April 1996– December 2000, 31 patients with advanced left ventricular dysfunction and moderate or moderate to severe MR underwent isolated CABG
Peri-operative complications Survival
No in-hospital deaths Five late deaths (16%), in patients with no MR improvement The NYHA class improved from a mean of 3.65"0.49–1.32"0.60 (P-0.001) LVEF measurements showed
This study supports the use of coronary artery bypass grafting alone in patients with severely depressed left ventricular function and moderate-to-severe MR Small study. Short followup
(Continued on next page)
ARTICLE IN PRESS A.R. Srivastava et al. / Interactive CardioVascular and Thoracic Surgery 6 (2007) 538–546
540 Table 1 (Continued) Author, country, and date Study type (level of evidence)
Patient group
Moderate (grade 2) 4 (13%) Moderate-to-severe (grade 3) 27 (87%)
Outcomes
MR regression
Mean follow-up: 21.35"13.24 months
Key results
Comments
a significant improvement, from a mean of 0.25"0.05–0.43"0.09 (P-0.001)
Lacks a control group for comparisons
Severity of MR decreased to a mean of 1.35"0.96, from 2.87"0.34 preoperatively (P-0.001)
Only patients with advanced LV dysfunction included Mitral regurgitation did not improve postoperatively in five patients, and these were the patients who died
Campwala et al., 2006, Eur J Cardiothorac Surg, USA w5x Retrospective cohort study (level 2b)
Prifti et al., 2001, J Heart Valve Dis, Italy w6x Retrospective cohort study (level 2b)
July 1993–December 2001, 438 patients with grade 0q to 2q MR (0q in 108, 1q in 180, 2q in 150) underwent isolated CABG
Changes in MR grade, postoperatively
Mean follow-up: 1.6 years
January 1994–July 2000, 99 patients with impaired LV function (LVEF 1730%) with ischaemic MR (grade 2–3). 49 underwent CABG and mitral valve repairyreplacement (group 1), 50 underwent isolated CABG (group 2)
Of the 108 patients without MR 10% (11) had 3–4qMR postoperatively. 12% (21) of the patients with 1q MR (180) progressed to 3–4q, whereas 25% (37) of those with 2q MR(150) showed progression to 3–4q MR Independent predictors of MR progression: female gender, renal insufficiency, lack of beta blocker use, MR grade, left bundle branch block
Hospital mortality Complications
Insignificant difference in hospital mortality Higher peri-operative complications in group 2 (Ps0.02) (prolonged need for inotropes, low cardiac output, AF) Significant improvement in LVEF in group 1 vs. 2 (Ps0.04)
Highest rate of MR progression in patients with pre-existing 2q MR (25%, Ps0.0002) Only those patients selected in which both pre and postoperative echo was performed, leaving room for bias in inclusion of more symptomatic patients needing echo evaluation and potentially magnifying the results. Importantly, this paper identifies risk factors for MR progression, however, only preoperative medication use was correlated with MR progression, no data on postoperative drug use and drug treatment of MR At 3-year follow-up, survival and freedom from reoperation significantly better in patients undergoing combined surgery Small study
Survival
Better 1, 2, 3-year survival in group 1 (Ps0.009)
NYHA class
Better improvement in NYHA class in group 1 (Ps0.001)
Only patients with impaired LV function included
LV function Mean follow-up: 34 months
Harris et al., 2002, Ann Thorac Surg, USA w7x Retrospective cohort study
January 1991–September 1996, 176 Patients with CAD and moderate (2q or 3q) MR, undergoing CABG alone (ns142) or CABGqMitral valve procedure (ns34,
Selection criteria for concomitant annuloplasty not standardised and based on surgeons discretion only. Approach to mitral valve not uniform (CarpentierEdwards ring in 37, limited posterior annuloplasty with pericardial patch in 6, valve replacement in 5) Operative risk Late mitral valve function Survival
Operative risk of 9% for CABG vs. 21% for combined procedure (Ps0.047) Choice of surgical procedure, NYHA class, severity of MR were not significant predictors of early mortality 16% patients undergoing repair still had 3–4q MR vs. 36% patients with isolated CABG had
Intervention on the mitral valve improved survival over CABG alone in patients with advanced heart failure CABG alone was
(Continued on next page)
ARTICLE IN PRESS A.R. Srivastava et al. / Interactive CardioVascular and Thoracic Surgery 6 (2007) 538–546
541
Table 1 (Continued) Author, country, and date Study type (level of evidence)
Patient group
(level 2b)
repairs29, replacements5) Mean follow-up: 5.1"0.3 years and 4.7"0.6 years, respectively
Outcomes
Key results
Comments
3–4qMR
inadequate to correct MR in 1y3rd patients
MR grade is more stable after repair (15% early vs. 17% late), in CABG alone it increased from 36% (early) to 53% (late) Late functional status
21 patients with NYHA class IIIyIV undergoing CABG alone had worse late survival than 14 patients with similar functional class and undergoing Mitral valve repair with CABG. (Ps0.005). Late survival similar for those in NYHA class I or II
Selection criteria for concomitant annuloplasty not standardised and based on surgeons discretion only. Approach to mitral valve not uniform (repair 29, replacement 5) technique of repair not provided Repair group had significantly more patients with NYHA class IIIyIV symptoms (41% vs. 15%, Ps0.002)
Schroder et al., 2005, Circulation, USA w8x Retrospective cohort study (level 2b)
May 1999–September 2003, 3264 consecutive CABG, 28.2% (ns922) had mild and 4.0% (ns130) had moderate MR Median follow-up: 3 years
Death
Mild to moderate MR is a significant independent predictor of death when compared with patients with noytrace MR (hazard ratio (HR) 1.44, P-0.001) and is also a predictor of worse event-free survival (HR 1.34, P-0.001)
Event-free survival
Mild MR independently increased risk factor of death (HR 1.34, Ps0.01) and worse event free survival (HR 1.34, P-0.001) Increasing MR severity had an increased risk of death and heart failure hospitalisation Similar results, if patients with leaflet pathology are eliminated from study
Mild to moderate MR after CABG increases risk of death and admission for heart failure treatment Large study. Important strength lies in the elimination of patients with leaflet pathologies – directly addressing ischaemic MR and in afterload management by phenylepherine to avoid underestimation of MR by intra-operative TEE No follow-up echo data available on the progressionyregression of MR If repair of ischaemic MR will improve survival is not known from the study
Lishan et al., 2001, Circulation, USA w9x Retrospective cohort study (level 2b)
January 1992–August 1999 Of the 269 patients of CAD with Moderate MR, 133 (49%) underwent CABGq mitral valve repair, 136 (51%) underwent isolated CABG Patients undergoing isolated CABG were evaluated for resolutionyprogression of MR
Progressiony Regression of MR after CABG
Of the 68 patients undergoing postoperative TTE, 40% had residual MR of at least moderate severity (representing ;20% of the study population). 52% with 2q MR and only 8% had resolution of MR to trace or less
CABG alone has an inconsistent and weak impact on moderate ischaemic MR Small study
Mean MR grade decreased from 3.0 to 2.3 Postoperative echo available only for 68y136 patients (50%), possibly including more symptomatic patients undergoing postoperative echo. However, presuming that none of the patient’s not undergoing post op echo had residual MR; patients with moderate residual MR would still make 20% of the total study cohort Inclusion of patients undergoing CABGqmitral valve repair could have
(Continued on next page)
ARTICLE IN PRESS A.R. Srivastava et al. / Interactive CardioVascular and Thoracic Surgery 6 (2007) 538–546
542 Table 1 (Continued) Author, country, and date Study type (level of evidence)
Patient group
Outcomes
Key results
Comments
increased the significance of the paper Effect of residual MR on survivalyfunctional status not known from the study Duarte et al., 1999, Ann Thorac Surg, USA w10x Case control study (level 3b)
1977–1983, 58 patients with moderate MR treated with CABG alone and compared with 58 matched patients with CAD and no MR undergoing CABG during the same time period
Hospital mortality
Non significant difference in early mortality (3.4% vs. 6.9%) 26% vs. 34% alive at follow-up (Ps0.42)
Late survival
Similar 5- and 10-year survival rates
Angina, CHF class at followup
Larger proportion of cardiac deaths in patients with MR (61% vs. 30%), but undetermined causes of death higher in patients without MR, 30% vs. 17%)
Mean follow-up: 10.3"5.1 years (study group) and 10.4"5.9 years (control group)
Moderate MR treated with CABG alone does not appear to confer an added deleterious risk with respect to late survival Strength lies in a matched control group and long follow-up. However, no sample size calculation provided Mean EF in control and test group 0.53"0.17. Whereas other studies suggest poorer outcome with untreated moderate MR in patients with LV dysfunction Larger proportion of cardiac deaths in patients with MR Inclusion of patients undergoing repair of LV aneurysm, which itself may decrease MR, is a potential bias, in the study
Tolis et al., 2002, Ann Thorac Surg, USA w11x Retrospective cohort study (level 2b)
April 1986–December 1996, 183 patients with ischaemic cardiomyopathy and EF F30%, out of 75 patients with documented MR status, and 49 had 1q to 3q MR and 26 had no MR
Hospital mortality
1y49 in hospital death (2%), in a patient with 2q MR, no deaths in patients without MR
LVEF improvement
Similar improvement in EF in both groups
MR improvement
Post op MR improved from 1.7 to 0.5 in patients with 1q or more MR
CHF
NYHA class improved from 3.25 to 1.75 improvement
Late survival
Similar 1, 3, 5-year survival
In patients with advanced ischaemic cardiomyopathy and mild to moderate MR, isolated CABG suffices Small sample size Majority of patients with mild MR (18 with 1q MR and 26 with 2q). Only 5 patients with 3q MR were included Only one death in the entire group of 75 patient (in a patient with 2q MR) does not permit a reliable analysis with this variable Data incomplete, whether the data provided are in mean, median or average is not mentioned. Standard deviations or interquartile range are not provided, making assessment of overlap difficult Only patients with advanced LV dysfunction included. Authors acknowledge that little data
(Continued on next page)
ARTICLE IN PRESS A.R. Srivastava et al. / Interactive CardioVascular and Thoracic Surgery 6 (2007) 538–546
543
Table 1 (Continued) Author, country, and date Study type (level of evidence)
Patient group
Outcomes
Key results
Comments
exist that can prove that survival in patients with ischaemic cardiomyopathy can be improved by surgical management, and long time mortality remains considerable Ryden et al., 2001, Eur J Cardio-thorac Surg, Sweden w12x Retrospective case control study (level 3b)
1995–1998, 4798 patients undergoing isolated CABG, 89 with grade 2y4 ischaemic MR, with 89 patients without MR and matched for sex, age, EF and month of operation serving as control
Hospital mortality
Identical 30-day mortality. Similar perioperative morbidity
Survival
Survival not significantly different between the 2 groups (Ps0.21)
Angina
Similar relief in angina in both groups
Postoperative echo findings
40 patients in the study group had postoperative echo. 63% had reduced MR, 35% had unchanged MR, one had increased MR grade (2%)
Mean follow-up: 28"15 months Mallidi et al., 2004, J Thorac Cardiovasc Surg, Canada w13x Retrospective cohort study (level 2b)
January 1 1994–June 30 2002, 6443 patients underwent isolated CABG 163 patients had 1q, 2q functional MR on left ventriculography. They were matched 1:2 (ns326) with patients without MR
Hospital mortality
Similar hospital mortality and perioperative complications
Perioperative complications Late functional status
Retrospective cohort study (level 2b)
Propensity matching with patients without MR yielded 210 matched pairs for comparisons Mean follow-up: 3.6"1.8 years
Small sample size
Patients with mild to moderate MR treated with CABG alone had worse event-free survival, poorer late functional status and high incidence of MR progression Well conducted study
Overall survival
Event-free survival
1980–2000, 467 patients moderate (2q) ischaemic MR underwent isolated CABG
Matched study and control groups
Short follow-up
Insignificant difference in overall survival Patients with MR had higher incidence of NYHA 3, 4 symptoms (Ps0.0046), with significant increase in NYHA class as the degree of MR increased (Ps0.0042)
Lam et al., 2005, Ann Thorac Surg, USA w14x
CABG on patients with grade 2 MR reduces angina and improves functional status to same extent as in CABG patients without MR
Worse event free survival in patients with MR (Ps0.0258)
Well matched test and control groups (age, gender, diabetes, extent of coronary disease, EF, timing of surgery, NYHA class, renal dysfunction, year of operation)
Higher incidence of CHF in patients with MR (P-0.0001)
However, does not prove whether adding Mitral valve repair at CABG will improve outcome
Of the 49 patients with MR where follow-up echo was available, 15 (30.6%) had progression in the grade of MR and of these 47% (ns7) were hospitalised for CHF. 2.9% (ns1) of 34 patients with mild (or less) MR required hospitalisation for CHF (P-0.0001)
Grading of MR is on the basis of ventriculography, which is known to be unreliable for this purpose
Hospital mortality
Hospital mortality 3.3% (7y210) in patients with MR and 0% (0y210) in patients without MR (Ps0.01)
Survival
Survival worse in patients with MR than those without it (at 6 months – 91% vs. 99%, at 1 year – 89% vs. 98% and 73% vs. 85% at 5 years, Ps0.003)
Patients with unrepaired moderate ischaemic MR undergoing CABG have a greater early postoperative risk of death than otherwise similar patients undergoing the same procedure Well conducted study Very well ‘propensity matched’ control and study groups Impact of repair of ischaemic MR on survival not explored
(Continued on next page)
ARTICLE IN PRESS A.R. Srivastava et al. / Interactive CardioVascular and Thoracic Surgery 6 (2007) 538–546
544 Table 1 (Continued) Author, country, and date Study type (level of evidence)
Patient group
Outcomes
Key results
Comments
Paperella et al., 2003, Ann Thorac Surg, Canada w15x
1987–1999, 1939 underwent isolated CABG. Based on left ventriculogram, 142 (7.3%) with 2q MR
Operative mortality
Insignificant difference in operative mortality
Perioperative complications
Higher incidence of perioperative complications in patients with MR
Survival
Lower survival in patients with MR (60% vs. 78% 10 year survival, Ps0.000)
Freedom from re-hospitalisation
Freedom from re-hospitalisation, worse in patients with MR (21% vs. 55%, Ps0.000)
Preoperative profile of study and control groups grossly unmatched (Age, gender, angina, CHF, MI, timing of surgery, diabetes, Hypertension, smoking, renal dysfunction, preop. IABP use, AF-all very significantly different) and also for extent of coronary artery disease and LV dysfunction, making intergroup comparisons difficult
Retrospective cohort study (level 2b)
If 3q MR was down graded to 2q at intraop. TEE, they underwent CABG alone and included in the study (ns25) Total study cohort of 167 patients
In patients good LV function (grade 1, 2) survival was similar among patients with or without MR. However, in patients with poor LV function (grade 3, 4) survival was worse for patients with MR (53% vs. 75%, Ps0.001) at 10 years
Control group of patients with 0–1q MR
Only 120y167 patients with ischaemic etiology, 24 with valvular pathology and 23 indeterminate If patients with 3q MR downgraded to 2q or 3q by intraop TEE, they were included in the study (25y167) and underwent CABG alone. Intraop TEE is known to downgrade severity of MR. This is another potential bias of the study, moreover outcome and survival in patients where MR severity was not downgraded is not provided rendering results difficult to interpret
Wong et al., 2005, Ann Thorac Surg, USA w16x Retrospective cohort study (level 2b)
1991–2001, 8442 patients undergoing CABG. 325 patients with 3q (moderate) MR on TTE. Of these, 251 patients with ischaemic MR form the study cohort. 220 underwent isolated CABG, 31 underwent CABGqannuloplasty Median follow-up: 4.3 years
Hospital mortality
Non-significant difference in hospital mortality and perioperative complications
Perioperative complications
Annuloplasty not independently associated with long-term survival
Residual MR
In follow-up echo of 109 patients all had at least 1q MR. Mean MR grade- 2.0 in patients undergoing CABGqannuloplasty vs. 2.6 in patients undergoing CABG alone (Ps0.005)
Survival
Isolated CABG appeared to produce long-term survival similar to CABGq annuloplasty. Annuloplasty significantly improved the severity of MR over CABG alone Mean MR grade of 2.0 after annuloplasty is inadequate by current standards
No association between death and improvement or deterioration in the grade of MR, in CABG only group
Sample size in patients undergoing annuloplasty small
No significant difference in mortality for concomitant annuloplasty
Functional outcomes (NYHA class, Readmissions, CHF) not measured Less than half (109y251) of all patients had follow-up echocardiography Selection criteria for concomitant annuloplasty not standardised and based on surgeons discretion only. Annuloplasty technique too were not uniform (rings were not undersized in the
(Continued on next page)
ARTICLE IN PRESS A.R. Srivastava et al. / Interactive CardioVascular and Thoracic Surgery 6 (2007) 538–546
545
Table 1 (Continued) Author, country, and date Study type (level of evidence)
Patient group
Outcomes
Key results
Comments
early part of the series, 9 incomplete rings and the remainder rigid or semi-rigid compete rings) Di Mauro et al., 2006, Ann Thorac Surg, Italy w17x Retrospective cohort study (level 2b)
January 1988–December 2002, 6108 patients underwent isolated CABG. 239 (3.9%) with ischaemic cardiomyopathy, out of these 176 had functional MR. Propensity matched group of 70 patients with no or mild MR (group A), were matched with 70 patients with moderate MR (group B)
Survival
Similar early survival
NYHA class
After a mean of 99.5"25.0 months, 81 patients were alive. By Cox analysis, moderate MR is an independent factor for lower freedom from death, cardiac death, cardiac death and ischaemic event, and death and NYHA class III or IV
Echo findings
After a mean of 62"28 months, 87.8% of survivors had an echo assessment-favorable LV remodeling, significant increase in LVEF and reduction in LV volumes in patients without MR, whereas in patients with MR, LV volumes and EF remained unchanged and MR worsened (Ps0.023)
Moderate MR is an independent variable that can impair survival, freedom from cardiac death, freedom from cardiac event and quality of life in patients with ischaemic cardiomyopathy Well conducted study Follow-up 100% complete Propensity matched study and control group, differing only in NYHA class. Even the surgical technique did not significantly differ between groups Only patients with advanced LV dysfunction included (EF-0.30) Whether repair of ischaemic MR will improve survival is not known from the study
most ischaemic MR will resolve after CABG alone, with a significant number of patients showing progression (12–25% w5x, 30.6% w13x) and many more with an unchanged MR grade (28% w5x, 52% w9x, 35% w12x). Although a significant number of patients will have some reduction in the MR grade (33% w5x, 63% w12x), complete resolution appears to be uncommon (14% w5x, 8% w9x). Even with reports that suggest otherwise w10, 12x, evidence is now mounting that residual MR in these patients will adversely effect survival w2, 8, 14, 17x; event-free survival w8, 13, 17x and late functional status w13, 17x. While it is known that any degree of MR after myocardial infarction negatively influences survival w18x and that the presence of MR in patients undergoing percutaneous intervention (PCI) portends a lower 3-year survival w19x, it appears unlikely that patients undergoing surgical revascularisation will have a different outcome. Results from 16 studies dealing with the subject (Table 1) though conflicting, support similar conclusions. While the negative impact of residual MR is now documented, the benefits of an additional mitral valve procedure are less convincingly established, with a few studies suggesting a survival benefit w6, 7x while others do not w3, 16x. Higher operative mortality, non-standardised mitral valve procedures, selection bias, small sample size and lack of long-term follow-up are critical drawbacks of these small number of studies. In addition, since all these studies
are retrospective, they have a questionable validity in the present era (when mortality for combined CABG and mitral valve repair is decreasing and results of restrictive ring annuloplasty are improving). A common drawback for all studies is the lack of data on the postoperative medical management of MR, and it still needs to be shown whether a surgical approach will yield better results over an optimised and aggressive medical management of MR in patients post-CABG. As already stated, many patients with coronary disease and MR will not show remission after CABG alone w5, 9, 12, 13x, however, it is equally important to realise that a significant number will, and a blanket procedure on the mitral valve for all patients may be considered unacceptable for many surgeons. There is evidence to suggest that higher preoperative MR grade, LV dysfunction, lower incidence of significant PDA stenosis grafted, LBBB and lack of beta blocker use are risk factors for postoperative MR progression w5x. However, identification of preoperative variables that reliably predict the need to address the mitral valve at the time of CABG is imperative and needs to be directly addressed in future studies and may have a more crucial impact on the issue. 7. Clinical bottom line We conclude that there is good evidence to suggest that moderate mitral regurgitation in patients undergoing iso-
ARTICLE IN PRESS 546
A.R. Srivastava et al. / Interactive CardioVascular and Thoracic Surgery 6 (2007) 538–546
lated CABG adversely affects survival and mitral regurgitation does not reliably improve after CABG alone. Unfortunately, the evidence to support mitral valve repair at the time of CABG to improve long-term survival is still weak. On balance, patients with moderate ischaemic mitral regurgitation having CABG should have mitral repair at the same time, although the evidence to support this is weaker than one might like.
w9 x
w10x
w11x
References w12x w1x Dunning J, Prendergast B, Mackway-Jones K. Towards evidence-based medicine in cardiothoracic surgery: best BETS. Interact CardioVasc Thorac Surg 2003;2:405–409. w2x Grossi EA, Crooke GA, Digiorgi PL, Schwartz CF, Jorde U, Applebaum RM, Ribakove GH, Galloway AC, Grau JB, Colvin SB. Impact of moderate functional mitral insufficiency in patients undergoing surgical revascularization. Circulation 2006;114:I573–I576. w3x Kang DH, Kim MJ, Kang SJ, Song JM, Song H, Hong MK, Choi KJ, Song JK, Lee JW. Mitral valve repair vs. revascularization alone in the treatment of ischemic mitral regurgitation. Circulation 2006;114:I499– I503. w4x Ogus NT, Us MH, Ogus H, Isik O. Coronary artery bypass grafting alone for advanced ischemic left ventricular dysfunction with significant mitral regurgitation: early and mid-term outcomes in a small series. Tex Heart Inst J 2004;1:143–148. w5x Campwala ZC, Bansal RC, Wang N, Razzouk A, Pai RG. Mitral regurgitation progression following isolated coronary artery bypass surgery: frequency, risk factors, and potential prevention strategies. Eur J Cardiothorac Surg 2006;29:348–354. w6x Prifti E, Bonacchi M, Frati G, Giunti G, Babatasi G, Sani G. Ischemic mitral valve regurgitation grade II–III: correction in patients with impaired left ventricular function undergoing simultaneous coronary revascularization. J Heart Valve Dis 2001;10:754–762. w7x Harris KM, Sundt TM III, Aeppli D, Sharma R, Barzilai B. Can late survival of patients with moderate ischemic mitral regurgitation be impacted by intervention on the valve? Ann Thorac Surg 2002;74:1468–1475. w8x Schroder JN, Williams ML, Hata JA, Muhlbaier LH, Swaminathan M, Mathew JP, Glower DD, O’Connor CM, Smith PK, Milano CA. Impact of mitral valve regurgitation evaluated by Intraoperative transesophageal
w13x
w14x
w15x
w16x
w17x
w18x
w19x
echocardiography on long-term outcomes after coronary artery bypass grafting. Circulation 2005;112:I293–I298. Aklog L, Filsoufi F, Flores KQ, Chen RH, Cohn LH, Nathan NS, Byrne JG, Adams DH. Does coronary artery bypass grafting alone correct moderate ischemic mitral regurgitation? Circulation 2001;104:I-68–I-75. Duarte IG, Shen Y, MacDonald MJ, Jones EL, Craver JM, Guyton RA. Treatment of moderate mitral regurgitation and coronary disease by coronary bypass alone: late results. Ann Thorac Surg 1999;68:426–430. Tolis GA Jr, Korkolis DP, Kopf GS, Elefteriades JA. Revascularization alone (without mitral valve repair) suffices in patients with advanced ischemic cardiomyopathy and mild-to-moderate mitral regurgitation. Ann Thorac Surg 2002;74:1476–1481. Ryden T, Bech-Hanssen O, Brandrup-Wognsen G, Nilsson F, Svensson S, Jeppsson A. The importance of grade2 ischemic mitral regurgitation in coronary artery bypass grafting. Eur J Cardiothorac Surg 2001;20:276– 281. Mallidi HR, Pelletier MP, Lamb J, Desai N, Sever J, Christakis GT, Cohen G, Goldman BS, Fremes SE. Late outcomes in patients with uncorrected mild to moderate mitral regurgitation at the time of isolated coronary artery bypass grafting. J Thorac Cardiovasc Surg 2004;127:636–644. Lam BK, Gillinov MA, Blackstone EH, Rajeswaran J, Yuh B, Bhudia SK, McCarthy PM, Cosgrove DM. Importance of moderate ischemic mitral regurgitation. Ann Thorac Surg 2005;69:462–470. Paparella D, Mickleborough LL, Carson S, Ivanov J. Mild to moderate mitral regurgitation in patients undergoing coronary bypass grafting: effects on operative mortality and long-term significance. Ann Thorac Surg 2003;76:1094–1100. Wong DR, Agnihotari AK, Hung JW, Vlahakes GJ, Akins CW, Hilgenberg, Madsen JC, MacGillivray TE, Picard MH, Torchiana DF. Long-term survival after surgical revascularization for moderate ischemic mitral regurgitation. Ann Thorac Surg 2005;80:570–578. DiMauro M, Di Giammarco G, Vitolla G, Contini M, Iaco AL, Bivona A, Weltert L, Calafiore AM. Impact of no to moderate mitral regurgitation on late results after isolated coronary artery bypass grafting in patients with ischemic cardiomyopathy. Ann Thorac Surg 2006;81:2128–2134. Lamas GA, Mitchell GF, Flaker GC, Smith SC Jr, Gersh BJ, Basta L, Moye L, Braunwald E, Pfeffer MA. Clinical significance of mitral regurgitation after acute myocardial infarction. Survival and ventricular enlargement investigators. Circulation 1997;96:827–833. Ellis SG, Whitlow PL, Raymond RE, Schneider JP. Impact of mitral regurgitation on long-term survival after percutaneous coronary intervention. Am J Cardiol 2002;89:315–318.
