Factors affecting regression of mitral regurgitation following isolated coronary artery bypass surgery

Fate of MR following CABG is variable. Predictors of MR regression following CABG alone are not known.

From our surgical registry, CABG patients with both pre-operative and post-operative resting echocardiograms at our institution were screened. Of the 523 patients identified, 92 had 3+ (n = 65) or 4+ (n = 27) MR on the pre-operative echocardiogram on a 0-4 scale, who had isolated CABG. MR regression was correlated with clinical, operative, electrocardiographic and echocardiographic variables.

age 68+/-11 years, 62% male, and LVEF 37+/-15%. MR grade decreased from 3.3+/-0.5 to 2.3+/-1.2 post-CABG. Residual 3 or 4+ MR post-CABG was present in 43 (47%) patients. Regression of MR (n=49) was associated with reductions in LV end-diastolic (P = 0.006) and end-systolic (P = 0.0005) dimensions, improvement in LVEF (P = 0.01), longer cross-clamp time (P = 0.04), use of beta-blockers (P = 0.04) and lower presence of CVA as a possible marker of lower atherosclerotic burden (P = 0.03). There was a trend towards increased mortality (P = 0.3) with residual 3-4+ MR over a mean follow-up of 3.9 years.

In nearly half of patients with 3-4+ MR, MR does not regress with CABG alone. Residual MR may be associated with increased mortality. Regression of MR is related to LV size reduction and improvement in LV function. Presence of myocardial viability, adequate revascularization, lack of excessive atherosclerotic burden and therapy with beta-blockers and ace-inhibitors may be critical for MR regression following CABG alone.