Mild to moderate mitral regurgitation in patients undergoing coronary bypass grafting: effects on operative mortality and long-term significance.

Background: Patients undergoing bypass grafting (CABG) often present with mitral regurgitation (MR). While surgical strategy for patients with either trace or severe MR is well established, the need for a valve procedure with mild (2) to moderate (3+) mitral regurgitation is controversial.

Methods: We reviewed 1,939 consecutive CABG patients (1987 to 1999). A preoperative echocardiogram performed when clinically indicated graded MR from 1 to 4+. Patient characteristics, hospital mortality, and long-term survival were compared between 167 patients with grade 2 to 3+ MR and controls. A multivariate analysis identified independent predictors for long-term mortality.

Results: The MR patients were more often female and older; had increased comorbidities including hypertension, diabetes, and heart failure; had more extensive coronary disease and worse left ventricular (LV) function; and required urgent surgery more often. Operative mortality was 0.8% in no MR patients and 1.8% in MR patients (p not significant). Long-term survival for MR patients with poor LV function (LV grade 3 to 4) was significantly lower (53% versus 75% at 10 years, p = 0.001). Independent predictors of poor long-term survival were advanced age, LV dysfunction, heart failure, diabetes, prior cerebrovascular accident, peripheral vascular disease, and no left internal mammary artery use.

Conclusions: Coronary artery bypass graft patients with mild or moderate MR have worse baseline characteristics but operative mortality with CABG alone is not significantly increased. Long-term prognosis for MR patients with poor LV function is worse compared with patients with no MR but MR was not an independent predictor of long-term mortality. To determine whether surgical correction of MR would improve results, a prospective randomized trial seems warranted.