Combined mitral valve repair and CABG do not provide additional benefits

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Annetine Gelijins (Department of Population Health Science and Policy, Icahn School of Medicine, Mount Sinai, New York, USA) and others report in The New England Journal of Medicine that mitral valve repair alongside coronary artery bypass grafting (CABG) does not reduce left ventricular reverse remodelling compared with CABG alone at one year in patients with multivessel disease and moderate functional mitral regurgitation. The combined procedure also doesnot reduce major adverse cardiac or cerebrovascular events compared with CABG alone.

Gelijns et al comment that the use of mitral valve repair alongside CABG in patients with moderate functional mitral regurgitation is “controversial”. They explain that some surgeons advocate a combined procedure because they believe it “may prevent progressive adverse remodelling, improve cardiac function, and reduce the risk of heart failure” but add that other surgeons believe CABG alone may improve left ventricular function and reduce left ventricular chamber size—“thereby restoring the functional integrity of the subchordal mitral valve apparatus”. The authors also comment that the controversy surrounding the additional of mitral valve repair to CABG is “based in part” on the lack of data from rigorous trials.

Therefore, the aim of their study was to compare CABG plus mitral valve repair to CABG alone. The primary endpoint was the degree of left ventricular reverse remodelling at 12 months, as measured by left ventricular end systolic volume index (LVESI). Secondary endpoints included a composite of major adverse cardiac or cerebrovascular events and the degree of residual mitral regurgitation.


Of 301 patients (all of whom had multivessel disease and moderate functional mitral regurgitation), 151 were randomised to receive CABG alone and 150 were randomised to receive CABG plus mitral valve repair. At 12 months, the mean LVESI was 46.1±22.4ml per square meter in the CABG alone group compared with 49.6±31.5ml per square meter in the CABG plus mitral valve repair group—a non-significant difference (p=0.61).

There were also no significant differences between groups in the rate of death (7.3% for the CABG alone group vs. 6.7% for the CABG plus mitral valve repair group; p=0.81) or in the combined endpoint of major adverse cardiac or cerebrovascular events (p=0.97 for the comparison). However, at 12 months, the proportion of patients with residual mitral regurgitation was significantly higher in the CABG alone group: 31% vs. 11.2% for the CABG plus mitral valve repair group (p<0.001).


Also although the number of adverse events was similar between groups, the rate of serious neurologic events was significantly higher in the CABG plus mitral valve repair group (p=0.03) as was the rate of supraventricular arrhythmias (p=0.03).


Gelijns et al conclude that their study did not “show a clinically meaningful advantage of adding mitral valve repair” to CABG, but add that longer term follow-up may “determine whether the observed difference in the prevalence of moderate or severe mitral regurgitation at one year will translate into a net clinical benefit for patients undergoing repair.”

 

Gelijns told Cardiovascular News: “There has been major controversy about the benefits of adding mitral valve repair to CABG in moderate ischaemic mitral regurgitation patients, leading to substantial variations in surgical practice. This rigorously conducted comparative effectiveness trial offers important outcome data at one-year to better guide clinical decision-making.” 

This study was presented as a late-breaking trial during the American Heart Association Scientific Sessions (15–19 November, Chicago, USA).

 

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