Review
Coronary Artery Bypass Grafting Versus Combined Coronary Artery Bypass Grafting and Mitral Valve Repair in Treating Ischaemic Mitral Regurgitation: A Meta-analysis

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Background

Ischaemic mitral regurgitation (IMR) is commonly manifested after coronary artery disease, but it is still controversial as to whether coronary artery bypass grafting (CABG) alone improves postoperative outcome.

Objectives

A focussed clinical question was designed and a meta-analysis of published studies was performed to identify the impact of mitral valve repair (MVR) in patients with IMR undergoing CABG versus those undergoing CABG alone.

Methods

Using the Medline database, the Cochrane clinical trials database and online clinical trial databases, we reviewed all RCTs and observational studies examining the impact of MVR and CABG in treating patients with IMR. We searched for literature published before September 2013 and earlier.

Results

This analysis identified five studies which examined the impact of CABG alone versus combined CABG and MVR in treating patients with IMR, involving 1038 patients, with 423 patients undergoing CABG alone and 615 were performed combined CABG and MVR procedures. There was significant improvement in postoperative mitral regurgitation (MR) grade in combined group, comparing with CABG alone group (WMD: 1.34, 95% CI: 0.47 to 2.21, p = 0.003), but no significant differences were noted between the CABG plus MVR group and CABG alone group in terms of in-hospital mortality (OR: 0.84, 95% CI: 0.44 to 1.61, p = 0.60), MR grade improvement rate (OR: 0.19, 95% CI: 0.02 to 1.66, p = 0.13), postoperative mean NYHA functional class (WMD: 0.33, 95% CI: -0.29 to 0.94, p = 0.30) and five-year survival (OR: 0.77, 95% CI: 0.34 to 1.73, p = 0.53).

Conclusions

Compared with CABG alone, patients who underwent combined CABG and MVR procedures showed a greater improvement in postoperative MR grade, but in terms of in-hospital mortality, MR grade improvement rate, postoperative mean NYHA functional class and five-year survival, adding MVR to CABG surgery lacks evidence to show its superiority.

Introduction

Ischaemic mitral regurgitation (IMR) is a common complication after myocardial infarction (MI) with normal leaflet and chordal morphology, frequently following an inferior MI [1]. Nowadays, it is still controversial in the management of mild to moderate IMR at the time of coronary artery bypass grafting (CABG). There are several studies suggesting that isolated CABG (without mitral valve repair (MVR)) suffices, with dramatic improvement in ejection fraction, degree of mitral regurgitation (MR) and long-term survival [2], [3]. But other authors advocating MVR at the time of CABG have suggested that CABG alone will not correct moderate IMR in many patients, especially those with annular and ventricular dilation [4], [5], [6].

Therefore, we conducted a meta-analysis of the evidence obtained from published studies to compare the impact of CABG alone versus combined CABG and MVR in treating patients with IMR, which we thought can provide useful clinical evidence for the surgery management in treating IMR patients.

Section snippets

Methods

We performed this analysis according to the guidelines of the meta-analysis of observational studies in epidemiology group (MOOSE) [7].

Articles

Fifteen records were identified by the primary literature search. However, finally five studies [5], [15], [16], [17], [18] were included in this analysis, the other 10 studies were excluded because they were either laboratory studies, review articles, or irrelevant to the current analysis (Fig. 1). There were altogether 1038 patients included, with the publication year ranging from 2004 to 2009. The characteristics of each study are depicted in Table 2.

In the five included articles, four of

Discussion

IMR is not caused by intrinsic disease of the valve, but by left ventricular (LV) remodelling, dilation and dysfunction leading to geometric reconfiguration of the mitroventricular apparatus, which is strongly associated with poor outcomes in patients with advanced coronary artery disease [21], [22], [23], [24], [25], [26]. Adding MVR to patients with IMR still remains controversial, and the outcome is also unclear. [1], [19], [27], [28], [29], [30], [31], [32] For 1+ MR or less, most authors

Disclosure

The authors declare no conflict of interest.

Acknowledgments

We thank Dr. Xue Qian and Dr. Li Wei for their assistance in preparation of this manuscript and for their valuable advices on editing the manuscript.

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