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ORIGINAL ARTICLE
Year : 2015  |  Volume : 28  |  Issue : 1  |  Page : 114-120

Revascularization versus revascularization and repair in moderate chronic ischemic mitral regurgitation: a randomized trial


1 Department of Cardiothoracic Surgery, Faculty of Medicine, Menoufia University, Menouifa, Egypt
2 Department of Cardiothoracic Surgery, Faculty of Medicine, Cairo University, Cairo, Egypt
3 Department of Cardiothoracic Surgery, National Heart Institute, Cairo, Egypt

Date of Submission19-Jul-2014
Date of Acceptance10-Oct-2014
Date of Web Publication29-Apr-2015

Correspondence Address:
Mohamed T Abdulmonem
Cardiothoracic Surgery Department, National Heart Institute, Cairo
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1110-2098.155964

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  Abstract 

Objectives
The goal of this study was to determine whether the surgical management of moderate chronic ischemic mitral regurgitation (IMR) is to revascularize only or to revascularize and perform mitral valve repair as well.
Background
Ischaemic mitral regurgitation is a frequent complication of left ventricular global or regional pathological remodeling due to chronic coronary artery disease. Although there are numerous possible treatment modalities, the management of patients with moderate chronic IMR remains uncertain.
Patients and methods
Forty patients referred for coronary artery bypass grafting with moderate IMR and an ejection fraction more than 30% were randomized to receive coronary revascularization plus mitral valve repair (20 patients) or revascularization only (20 patients). Survivors were clinically and echocardiographically assessed early postoperatively and at 3 months' follow-up.
Results
There was no significant difference between the two groups as regards preoperative and demographic data. The operative time, ventilation time, and ICU stay were significantly higher in the repair group. Use of cardiac supports, complications, in-hospital mortality, and ward stay were not statistically significantly different. Postoperative and follow-up echocardiographic data showed no statistically significant difference in left atrial dimension, left ventricular dimension, and function between the two groups. Although the grade of mitral regurgitation showed improvement in both groups, there was significantly higher improvement in the repair group compared with the revascularization-only group.
Conclusion
Adding mitral repair to coronary revascularization in patients with moderate IMR may improve mitral regurgitation severity without additional risk. Improvement in functional capacity and left ventricular reverse remodeling was observed in both procedures.

Keywords: Coronary artery bypass graft, ischemic mitral regurgitation, moderate, repair


How to cite this article:
Dokhan AL, Khalil MA, Abu ollo MF, Abdulmonem MT. Revascularization versus revascularization and repair in moderate chronic ischemic mitral regurgitation: a randomized trial. Menoufia Med J 2015;28:114-20

How to cite this URL:
Dokhan AL, Khalil MA, Abu ollo MF, Abdulmonem MT. Revascularization versus revascularization and repair in moderate chronic ischemic mitral regurgitation: a randomized trial. Menoufia Med J [serial online] 2015 [cited 2019 Nov 22];28:114-20. Available from: http://www.mmj.eg.net/text.asp?2015/28/1/114/155964


  Introduction Top


Chronic ischemic mitral regurgitation (IMR) can be defined as follows: mitral regurgitation (MR) occurring more than 16 days after myocardial infarction (MI) with one or more left ventricular (LV) segmental wall motion abnormalities; significant coronary artery disease (CAD) in a territory supplying the wall motion abnormalities; and structurally normal mitral valve (MV) leaflets and chordae tendinae. The third criterion is important to exclude patients with organic MR and associated CAD [1].

There is vast inconsistency in the reported prevalence and severity of MR after MI, and this is due to differences in diagnostic methods, MR severity classifications, amount of LV dysfunction, treatment options, and time interval between MI and MR diagnosis [2].

Functional IMR occurs in up to 40% of patients after MI. It is usually mild or moderate in severity but is associated with an increased incidence of heart failure and death [3].

It is caused by LV remodeling and dilatation after MI, which tethers and pulls the MV apart, resulting in MR; the MV is normal in structure but is incompetent as a result of a dilated and dysfunctional left ventricle [4].

Chronic IMR can be reliably diagnosed with color Doppler echocardiography. Two-dimensional transthoracic echocardiography and transesophageal echocardiography (TEE) are the preferred diagnostic imaging tools. Echocardiography provides accurate information about LV dimensions and function, regional wall motion abnormalities, MR etiology, MR severity, and MV geometry, including annular dilatation and MV tenting [5].

A comprehensive intraoperative TEE examination in patients with IMR may have important implications for perioperative clinical decision making [6].

Being essentially a ventricular disease, caused by coronary stenosis, with effects on the papillary muscles, cords, and leaflet coaptation, IMR lends itself to several therapeutic targets. Coronary artery revascularization is necessary to recruit any hibernating myocardium and thus improve ventricular function. Revascularization can help limit future adverse remodeling that results from continuing ischemia or new infarction. However, revascularization alone cannot be relied on as sole therapy for IMR, because the principal cause of the regurgitation leaflet tethering caused by regional infarction cannot usually be reversed by revascularization [7].

The ischemic MV can be repaired during coronary artery bypass grafting (CABG) with the use of an annuloplasty ring, which achieves MV competency by restoring the size of the mitral annulus and increasing mitral leaflet coaptation [8].

Restrictive (or downsized or undersized) annuloplasty is the currently recommended approach. Annuloplasty corrects circumferential annular dilation, whereas downsizing corrects the septolateral displacement and thus reduces the tethering distance [9].

Observational studies have reported a reduction in the severity of MR with the addition of MV repair to CABG, but an improvement in functional capacity or survival has not been demonstrated [10].

The aim of the work was to determine whether the surgical management of moderate chronic IMR is to revascularize only or to revascularize and perform MV repair as well.


  Patients and methods Top


Forty randomized, consecutive patients with moderate IMR on preoperative echocardiography underwent clinical and echocardiographic assessments before surgery, early after surgery, and at 3 months' follow-up. All patients had CAD and grade 2+ or 3+ MR. All patients were prospectively randomized to either CABG in combination with MV repair (repair group, n = 20) (group I), or CABG only (revascularization only group, n = 20) (group II), with the decision to perform MV repair being at the discretion of the surgeon.

Inclusion criteria included patients with moderate chronic IMR 8 cm 2 < RJA > 4 cm 2 , (II/IV), (III/IV) with all components of the MV having a normal structure in the preoperative echocardiography.

Exclusion criteria included patients with organic MV disease, including prolapse of mitral leaflets, ruptured chordae, and rupture of papillary muscles, mild (I/IV, RJA < 4 cm 2 ) or severe (IV/IV, RJA > 8 cm 2 ) MR, significant aortic valve disease, congenital heart diseases, redo or emergency surgery, ejection fraction less than 30%, and impaired renal or liver functions.

Preoperative counseling: Before surgery, a brief explanation of the steps of the operation, the postoperative events, and the intensive care stay was given to the patient.

The Ethics Committee of the faculty of medicine, Menoufia University, approved the data collection, and patient consent was obtained.

Patients in both groups were matched for demographic data on age, sex, risk factors for ischemic heart disease, and history of previous MI.

Operative technique

All patients were anesthetized with fentanyl at 5-10 μg/kg and sodium thiopental at 4-5 mg/kg. Endotracheal intubation was facilitated with a nondepolarizing muscle relaxant, pancuronium, at 0.08 mg/kg. Anesthesia was maintained with either inhalational sevoflurane or isoflurane 0.5-1% and a supplemental hypnotic dose of propofol at 0.5-1 mg/kg.

All surgical procedures were performed through midline sternotomy under normothermic cardiopulmonary bypass with intermittent antegrade warm-blood cardioplegia. All patients underwent full revascularization, and prosthetic mitral annuloplasty was performed only in the repair group. All patients underwent conventional multivessel CABG with the use of internal mammary arteries (LIMA), as well as saphenous vein grafts.

The MV was exposed in the repair group after completion of distal anastomoses. The exposure was routinely done through either left atriotomy incision, a vertical trans-septal approach along the right border of the foramen oval, leaving the left atrial roof untouched, or biatrial trans-septal incision. Direct visual inspection and assessment of the MV leaflets, annulus, chordae tendineae, and papillary muscles was carried out.

Ring size (Carpentier Edwards Physioring; Edwards Lifesciences, Irving, California, USA) was determined after careful measurement of the height of the anterior leaflet and standard measurement of the intertrigonal distance and then downsizing by two sizes.

Rings were inserted using 12-16 deep U-shaped simple horizontal sutures using ethibond 2-0. All rings were of size 28. However, one patient received an additional Alfieri stitch, as decided by the surgeon.

Left atriotomy was closed using a running polypropylene 3/0 suture. Right atriotomy was closed using a running polypropylene 4/0 suture.

All patients had intraoperative TEE assessment of LV and valve function. MV repair was considered successful if there was no residual MR and a leaflet coaptation length of at least 8 mm at the A2-P2 level.

Operative data on total pump time, aortic cross-clamp time, and number of distal anastomoses were collected.

Postoperative data on the use of inotropic support, insertion of intra-aortic balloon pump (IABP), time of mechanical ventilation, ICU stay, ward stay, postoperative echocardiography, and in-hospital morbidity and mortality were also collected.

Follow-up data

All patients were followed up at our outpatient clinic after 3 months with assessment of NYHA functional class and echocardiography, which was performed by the same cardiologists. Follow-up was 100% complete.

Statistical analysis

The data collected were tabulated and analyzed using the statistical package for the social science software package, version 20, on an IBM compatible computer. Quantitative data were expressed as mean and SD (X ± SD) and analyzed by applying the Student t-test for comparison of two groups of normally distributed variables and the Mann-Whitney test for two groups of not normally distributed variables. Qualitative data were expressed as number and percentage and analyzed by applying the c2 -test. For the 2 × 2 table, if one cell had expected number less than 5, Fisher's exact test was applied.


  Results Top


Preoperative results

Patients' ages ranged from 38 to 72 years in group I and from 44 to 65 years in group II. There was no statistical difference in the mean age of the two groups. There was also no statistical difference between the two groups regarding sex distribution [Table 1].
Table 1: Sociodemographic characteristics of the studied groups of patients

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The distribution of risk factors for ischemic heart disease in the two groups was studied during history taking and is summarized in [Table 2]; there was no statistical difference between the two groups.
Table 2: Distribution of risk factors among the studied groups

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The preoperative dyspnea classified by NYHA classification was not statistically different between the two groups [Figure 1].
Figure 1: NYHA class in the two groups.

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Preoperative echocardiographic data showed no statistically significant difference in preoperative LV dimensions or function, but we had statistically significantly higher left atrial dimension in the repair group compared with the revascularization-only group [Table 3].
Table 3: Preoperative echocardiographic data for both groups

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Operative data

The operative time including total pump time and aortic cross-clamp time was significantly higher in the repair group (P < 0.001) while the mean number of grafts per patient was statistically higher in the revascularization-only group (P < 0.05) [Table 4].
Table 4: Intraoperative data for both groups

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Immediate postoperative data

All patients were transferred to the ICU where they were maintained on positive pressure ventilation, with continuous monitoring of vital signs.

The ventilation time and total ICU stay time were statistically higher in the repair group [Table 5]. However, among the patients who needed postoperative cardiac support (whether pharmacological or mechanical), 16 (80%) required pharmacological support and four required mechanical (20%) support in the repair group versus 11 (55%) and 3 (15%) in the revascularization-only group, which is not significantly different (P > 0.05) [Figure 2].
Figure 2: Use of cardiac support.

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Although the mean time of ward stay in days was higher in the repair group (7.33 ± 2.54, versus 6.18 ± 2.64 in the revascularization-only group), the difference was statistically insignificant (P = 0.16).
Table 5: ICU data for both groups

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Postoperative complications in the form of reopening, postoperative atrial fibrillation, MI, and nodal rhythm were insignificantly different between the two groups (P = 0.5).

A total of three in-hospital mortalities occurred: one patient (5%) in the repair group and two patients (5%) in the revascularization-only group; however, the difference was statistically insignificant.

Postoperative echocardiographic data were collected from the surviving patients (19 out of 20 patients in group I and 18 out of 20 patients in group II), which showed no statistically significant difference in left atrial dimension, LV dimension, and function between the two groups [Table 6]. Although the grade of MR showed improvement in both groups, there was highly significant improvement in the repair group compared with the revascularization-only group [Figure 3].
Figure 3: Postoperative grade of mitral regurgitation in both groups.

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Table 6: Postoperative echocardiographic data of both groups

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Follow-up data

Follow-up data were collected from all surviving patients (18 of 20 patients in group I and 18 of 20 patients in group II).

Comparison of echocardiographic data between the two groups showed no statistically significant difference in any of the parameters [Table 7] except for the grade of MR, which was significantly higher in the revascularization-only group [Figure 4].
Figure 4: Grade of mitral regurgitation in both groups at follow-up.

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Table 7: Echocardiographic data of both groups at follow-up

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  Discussion Top


In all, 31 (77.5%) patients had suffered a previous MI: 17 in group I (85%) and 14 in group II (70%), with no statistical difference between them.

This percentage of patients who had a positive history of a previous MI was comparable to the proportion in studies by John Chan et al. [11] (72.6%), Wong et al. [12] (79.3%), and Harris et al. [13] (80%).

With respect to the NYHA functional class of dyspnea, in our study 5, 35, and 60% of patients in group I (mean of 2.55 ± 0.60) and 10, 35, and 55% of patients in group II (mean of 2.45 ± 0.68) had grade I, II, and III NYHA functional class of dyspnea, respectively, with no statistically significant difference between them.

This result was slightly different from that of John Chan et al. [11] as in their study the number of patients in grade I, II, and III NYHA was 1 (3%), 22 (65%), and 11 (32%) in group I, versus 1 (3%), 25 (64%), and 13 (33%) in group II.

With respect to preoperative echocardiographic data, the mean ejection fraction in group I was 47.00 ± 11.03% compared with 48.75 ± 9.72% in group II, with no statistical difference between them. These results were relatively higher than those of John Chan et al. [11] (40.0 ± 17.3 and 40.3 ± 16.1), Goland and colleagues 168 (37 ± 11 and 39 ± 11%), Harris and colleagues 165 (38 ± 13.8 and 38.7 ± 12.6%), and Wong et al. [12] (39 ± 13.6 and 42.2 ± 15.3%) in the repair group and revascularization-only group, respectively.

The preoperative mean grade of MR was 2.50 ± 0.51 in group I versus 2.35 ± 0.48 in group II, with no statistically significant difference between them. In the repair group, 10 (50%) patients were in grade II and 10 (50%) patients were in grade III, versus 13 (65%) and 7 (35%) patients in the CABG-only group, respectively. This was comparable to the results of Harris et al. [13] and Wong et al. [12], in which the mean grade of severity was 2.6 ± 0.5, 2.1 ± 0.3, and 2.0 ± 0.9, 2.6 ± 0.8 in the repair group and CABG-only group, respectively. However, in both studies there was a statistically significant difference between the two groups (P = 0.001 and 0.005, respectively): the mean grade of severity was higher in the repair group in the study by Harris et al. [13] and lower in the same group in the study by Wong et al. [12].

With respect to operative data, analysis of total pump time and ischemic time revealed a significant difference between the two groups. This significant difference that was observed in favor of group I was due to the MV procedure.

There was no statistically difference between the two groups as regards the use of cardiac support, either pharmacological (inotropic drugs) or mechanical (IABP). In group I, 16 (80%) patients needed inotropic support, and in 4 (20%) patients IABP was inserted, whereas in group II 11 (55%) patients received inotropic support and in only 3 (15%) patients was IABP inserted.

Similarly, John Chan et al. [11] reported the use of IABP in 11 (33%) patients in group I and in 11 (29%) patients in group II, with no statistical difference (P = 0.57).

The survival rate was 95% in group I versus 90% in group II. John Chan et al. [11] reported 30 days' mortality in 1 (3%) patient in group I versus 1 (3%) patient in group II (P = 1.00).

When evaluating the efficacy of concomitant CABG plus MV repair as against CABG alone on the grade of MR in patients with moderate chronic IMR we found the following.

Our early postoperative results showed high statistical difference between the two groups in the grade of reduction of MR: complete resolution of MR was seen in 12 (63%) patients in group I versus none in group II. Some reduction in the severity of MR to grade I was noticed in 6 (31%) patients in group I versus 8 (44%) patients in group II, and to grade II in 10 (55%) patients in group II. However, these immediate changes in grade of MR was not accompanied by similar changes in LA dimension, LV dimension, and function; this was an expected finding as reverse remodeling if any to occur needs a longer time interval.

During follow-up, the mean grade of MR showed a statistically significant reduction in the mean grade of severity in comparison with baseline grade in group I (from 2.55 ± 0.60 to 0.61 ± 0.77, versus from 2.35 ± 0.48 to 1.37 ± 0.88 in group II, with statistically significant difference). In addition to reduction in the grade of severity of MR at follow-up, the echocardiographic data showed reverse remodeling in LA and LV dimensions together with improvement in LV function in both groups.

These results were comparable to those of John Chan et al. [11] in their study on 73 patients; 34 of them underwent concomitant MV repair at the time of CABG and 39 patients underwent CABG only. They found significant improvement in MR grade and LV volumes in their CABG+MV repair patients, in comparison with their CABG-only patients, within 12 months of follow-up, and these translated into an improvement in functional capacity and symptoms at 1 year.

These results were also comparable to those from another study from the Cleveland clinic foundation, which reported that moderate (2+) IMR does not resolve with CABG alone and, furthermore, is associated with reduced survival [14].

Similarly, in the study by Goland et al. [15] on 83 patients who had moderate IMR, 28 patients underwent concomitant MV repair at the time of CABG and 55 patients underwent CABG only. They found significant improvement in MR grade in their CABG+MV repair patients in comparison with their CABG-only patients within 12 months of follow-up (P < 0.0001).

Although the mean NYHA functional class showed no statistically significant group difference (P = 0.62), it was significantly improved over the follow-up period in both groups included in our study; however, the improvement was higher in group I (1.33 ± 0.48) than in group II (1.43 ± 0.72) without reaching statistical significance.

Limitations of the study

This study is limited by the small sample size and lack of long-term follow-up.

It is expected that future studies will address these limitations and will provide further insight into this controversial issue.


  Conclusion Top


The ischemic MV can be repaired during CABG with the use of an annuloplasty ring, which achieves MV competency by restoring the size of the mitral annulus and increasing mitral leaflet coaptation.

The benefit of MV repair over CABG alone is the reduction in the severity of MR with the addition of MV repair to CABG, which may affect LV dimension and function in the long term.

LV improvement in terms of functional capacity, NYHA functional class, and survival has been demonstrated in both procedures.


  Acknowledgements Top


Conflicts of interest

None declared.

 
  References Top

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Watanabe N, Ogasawara Y, Yamaura Y, Wada N, Kawamoto T, Toyota E, et al. Mitral annulus flattens in ischemic mitral regurgitation: geometric differences between inferior and anterior myocardial infarction: a real-time 3-dimensional echocardiographic study. Circulation 2005; 112 (Suppl): I458-I462.  Back to cited text no. 4
    
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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]



 

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