Indication for Mitral Valve Repair with CABG
Abstract & Commentary
By Michael H. Crawford, MD, Editor
Sources: Deja MA, et al. Influence of mitral regurgitation repair on survival in the surgical treatment for ischemic heart failure trial. Circulation 2012; 125:2639-2648. Kwon MH, et al. Functional, ischemic mitral regurgitation: To repair or not to repair? Circulation 2012;125:2563-2565.
When and if mitral valve repair should be added to coronary artery bypass grafting surgery (CABG) remains controversial. Consequently, this report from the Surgical Treatment for Ischemic Heart Failure (STICH) trial is of interest. STICH investigators randomized patients with a left ventricular ejection fraction (LVEF) ≤ 35% and coronary artery disease amendable to CABG to medical therapy or CABG. The addition of mitral valve repair was not randomized, but since there is a medical therapy group, patients with and without surgical repair of the mitral valve (MV) could be compared to medically treated patients with similar severity of mitral regurgitation (MR). The primary endpoint was survival over 5 years. The 1209 patients randomized were divided into those with none or trace MR, mild MR, or moderate-to-severe MR. Each group had roughly the same number of patients who received medical or surgical therapy. Increasing MR grade was associated with lower LVEF, larger LV volumes, more symptoms, and higher mortality. The frequency of MV repair increased with MR severity. In the medical arm, 50% of the patients with moderate-to-severe MR died as compared to 53% who had CABG alone and 43% of those who also had MV repair. In those with moderate-to-severe MR, after adjusting for baseline variables, the hazard ratio for survival was 0.41 (95% confidence interval, 0.22-0.77, P = 0.006) for CABG plus mitral surgery vs CABG alone. The authors concluded that adding MV repair to CABG in patients with LV dysfunction and moderate-to-severe MR may improve survival compared to CABG alone or medical therapy alone.
Commentary
This study makes several important points. First, the presence of even mild MR reduces survival in ischemic cardiomyopathy. However, surgical repair does not improve survival in the mild MR patients, probably because the added risk of repair outweighs the potential benefits. Second, MV repair in more severe MR patients undergoing CABG for ischemic cardiomyopathy increases the early complication rate prolonging hospital stay, but does not increase early mortality and reduces longer term mortality compared to CABG or medical therapy alone. This is probably because relieving more severe MR has enough benefit to outweigh the risks of surgery over the short and long term. Thus, MV repair should be considered when CABG is indicated for ischemic cardiomyopathy. Third, ischemic cardiomyopathy with moderate-to-severe MR has a high mortality with medical therapy and CABG alone (about 50%) and CABG plus MV repair (43%). Unfortunately, this study did not separate out moderate from severe MR cases. It may be that with severe MR in ischemic cardiomyopathy, LV mechanical support or transplantation should be considered as well.
The current European Society of Cardiology Guidelines suggest MV repair be considered if the LVEF is > 30% and the MR is moderate or severe. What is more controversial is what to do with lesser severity MR and those with lower EFs. Fortunately, there is a randomized trial being conducted comparing MV repair to no repair in ischemic cardiomyopathy patients undergoing CABG. Soon we should have more information.
When and if mitral valve repair should be added to coronary artery bypass grafting surgery (CABG) remains controversial.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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