Two-Year Outcomes of Surgical Treatment of Moderate Ischemic Mitral Regurgitation

Abstract

Background: In a trial comparing coronary-artery bypass grafting (CABG) alone with CABG plus mitral-valve repair in patients with moderate ischemic mitral regurgitation, we found no significant difference in the left ventricular end-systolic volume index (LVESVI) or survival after 1 year. Concomitant mitral-valve repair was associated with a reduced prevalence of moderate or severe mitral regurgitation, but patients had more adverse events. We now report 2-year outcomes.

Methods: We randomly assigned 301 patients to undergo either CABG alone or the combined procedure. Patients were followed for 2 years for clinical and echocardiographic outcomes.

Results: At 2 years, the mean (±SD) LVESVI was 41.2±20.0 ml per square meter of body-surface area in the CABG-alone group and 43.2±20.6 ml per square meter in the combined-procedure group (mean improvement over baseline, -14.1 ml per square meter and -14.6 ml per square meter, respectively). The rate of death was 10.6% in the CABG-alone group and 10.0% in the combined-procedure group (hazard ratio in the combined-procedure group, 0.90; 95% confidence interval, 0.45 to 1.83; P=0.78). There was no significant between-group difference in the rank-based assessment of the LVESVI (including death) at 2 years (z score, 0.38; P=0.71). The 2-year rate of moderate or severe residual mitral regurgitation was higher in the CABG-alone group than in the combined-procedure group (32.3% vs. 11.2%, P<0.001). Overall rates of hospital readmission and serious adverse events were similar in the two groups, but neurologic events and supraventricular arrhythmias remained more frequent in the combined-procedure group.

Conclusions: In patients with moderate ischemic mitral regurgitation undergoing CABG, the addition of mitral-valve repair did not lead to significant differences in left ventricular reverse remodeling at 2 years. Mitral-valve repair provided a more durable correction of mitral regurgitation but did not significantly improve survival or reduce overall adverse events or readmissions and was associated with an early hazard of increased neurologic events and supraventricular arrhythmias. (Funded by the National Institutes of Health and Canadian Institutes of Health Research; ClinicalTrials.gov number, NCT00806988.).

Figure 1. Wall-Motion Scores at Baseline, 1 Year, and 2 Years, According to the Presence of Postoperative Moderate or Severe Mitral Regurgitation

Shown are the results of analyses of each of 17 wall segments at rest for patients without moderate or severe mitral regurgitation and those with moderate or severe mitral regurgitation at 2 years after the procedure. Baseline values were recorded before the procedure. The values in parentheses are the mean wall-motion scores at three time points for each segment. Scores on the wall-motion index are as follows: 1, normal; 2, hypokinetic; 3, akinetic; 4, dyskinetic; and 5, aneurysmal. The sum of the wall-motion scores for the myocardial segments was divided by the number of segments to provide a wall-motion index. At 2 years, the relative percent improvement in the global wall-motion index was larger for patients free of moderate or severe mitral regurgitation than for those with mitral regurgitation (16.5±20.1% vs. 7.4±16.7%, P = 0.008). A chart showing the name of each numbered segment is provided in the Supplementary Appendix.

Figure 2. Rates of Death and Cardiovascular Events

Shown are the rates of death and a composite of major adverse cardiac and cerebrovascular events (which were defined as death, stroke, subsequent mitral-valve surgery, hospitalization for heart failure, or worsening New York Heart Association class) among patients undergoing either coronary-artery bypass grafting (CABG) or CABG plus mitral-valve (MV) repair. The tick marks show censoring of data.

Figure 3. Quality-of-Life Scores

Shown are the mean scores on the Medical Outcomes Study 12-Item Short-Form General Health Survey (SF-12) for physical health (Panel A) and mental health (Panel B) for patients undergoing either CABG alone or CABG plus mitral-valve repair. The SF-12 scale ranges from 0 to 100, with higher scores indicating better health. Panel C shows mean scores on the Minnesota Living with Heart Failure questionnaire; scores can range from 0 to 105, with higher scores indicating a lower quality of life. Panel D shows mean scores on the Duke Activity Status Index (DASI), on which scores range from 0 to 58, with higher scores indicating a better activity level. On these measures of quality of life, the only significant between-group difference was on the DASI (P = 0.02).