Preservation of the posterior leaflet during mechanical valve replacement for ischemic mitral regurgitation and complete myocardial revascularization.

Between 1980 and 1987, 40 patients with ischemic mitral insufficiency underwent mitral valve replacement (with a mechanical prosthesis) and coronary bypass grafting, 3.5 grafts per patient. The posterior mitral leaflet was preserved in 17 and resected in 23. Five arrived at operation in cardiogenic shock, 15 after recurrent episodes of pulmonary edema, and 20 electively, but in congestive heart failure. Twenty-five had unstable angina, and the remaining had chronic angina. Perioperative and early deaths occurred only in patients with an ejection fraction less than 35%. None of the 21 patients with an ejection fraction greater than 35% died, whereas eight of 19 with an ejection fraction less than 35% died, whereas eight of 19 with an ejection fraction less than 35% died (p less than 0.001). When causes of death in patients with an ejection fraction less than 35% were studied, operative and early mortality was zero of seven with preservation of the posterior mitral leaflet versus eight of 11 with excision of the leaflet (p = 0.035). We concluded that the high mortality in mitral valve replacement for ischemic mitral insufficiency is linked to an ejection fraction less than or equal to 35% and, in this particular group of patients, is due to the surgical destruction of the left ventricular chordae tendineae supportive apparatus. Preservation of this apparatus by preservation of the posterior mitral leaflet drastically reduces operative and early mortality. Preoperative cardiogenic shock, left ventricular aneurysmectomy, and multiple grafting (up to five grafts per patient) did not increase the risk of operation. Extensive revascularization (3.5 grafts per patient) provides improved long-term results.