Should Moderate MR Be Repaired During CABG?

Authors: Smith PK et al., N Engl J Med 2014 Nov 18;

Although a combined procedure may improve mitral regurgitation, other measures were not as positive.

The potential benefit of adding mitral valve repair (MVR) to coronary artery bypass grafting (CABG) in patients with moderate mitral regurgitation (MR) is uncertain. In this multicenter trial (NCT00806988), 301 patients with ischemic moderate MR (inclusion criterion for effective regurgitant orifice area [EROA], 0.2–0.4 cm2) were randomized to CABG plus MVR or to CABG alone (mean age, 65; men, 68%; left ventricular [LV] ejection fraction, ~40%). The primary endpoint, an echocardiographic measure of reverse LV remodeling, was LV end-systolic volume index (ESVI) at 12 months.

The mean EROA was 0.2 cm2 in both groups. Mean LVESVI at 12 months was similar in the two groups, with a mean decrease of 9 mL/m2. The groups showed no significant differences in survival or ejection fraction. However, total serious neurologic adverse events occurred more frequently with the combined procedures than CABG alone (9.6% vs. 3.1%); a similar but nonsignificant trend occurred with stroke (5.2% vs 1.5%; P=0.10). Postsurgical lengths of stay in intensive care units and overall were shorter in the CABG-alone group. Residual MR at 12 months occurred more frequently in the CABG-alone group (31% vs. 11%), which was mostly moderate rather than severe MR. Measures of quality of life did not differ between groups.

Comment
These results suggest that adding MV repair to CABG in patients with moderate MR reduces MR at 12 months, but does not improve reverse LV remodeling or improve survival or quality of life. Furthermore, this combined approach is associated with more neurologic events and longer lengths of stay. These findings are unlikely to settle this controversial management question, particularly since the degree of MR at baseline as assessed by the core lab was on the mild side of moderate. Determining whether the risks of the additional surgery are worth the improvement in MR grade requires longer follow-up and a larger trial powered for clinical endpoints.