Should a mild to moderate ischemic mitral valve regurgitation in patients with poor left ventricular function be repaired or not?

In recent years coronary artery bypass grafting (CABG) has been extended to include patients with very low left ventricular ejection fractions (LVEF), also frequently with co-existing mild to moderate mitral valve regurgitation (MR). The question is, should such a MR be corrected simultaneously with a myocardial revascularization or not? Between January 1989 and November 1994, 56 patients with preoperative LVEF < or = 25% and echocardiographic evidence of co-existing MR (Grade I: 41%, II: 46%, III: 13%) underwent primary CABG. None of them had simultaneous mitral valve surgery. Twenty-nine patients (52%) had a pulmonary artery pressure (PAP) > 40 mmHg. The mean preoperative LVEF was 17.9 +/- 4.6 (10-25), mean PAP 44.2 +/- 16.1 mmHg. An average of 4.5 +/- 1.5 grafts/patient were placed and five patients had simultaneous repair of a post-infarction left ventricular aneurysm. The overall mortality was 3.6% (2/56). Transient post-operative low cardiac output syndrome occurred in 16 patients (29%). Twenty-one patients (38%) had no postoperative complications at all. The 54 hospital survivors were followed up over a mean period of 12 months (3-36 months). There was one death (eight months postoperatively) and two graft occlusions, not requiring reoperation. At the end of the follow up echocardiography showed that 50 patients (93%) had no (31 patients) or only a very mild Grade I MR (19 patients). Four patients had Grade II MR, none of them requiring mitral valve surgery. All patients improved their NYHA functional class, from 3.4 +/- 0.8 to 1.9 +/- 0.7 and LVEF from 17.9 +/- 4.6 to 44.2 +/- 7.4 (p < 0.001). Coronary artery bypass grafting is a possible treatment for patients with very low LVEF, provided the patient has a two- or three-vessel disease with significant coronary artery stenosis (> 70%) and angina. Mortality and morbidity are low. Moderate co-existing MR (Grade I-III) seems to normalize after myocardial revascularization and should not be surgically corrected therefore at the primary operation.