Data Collection and Study Outcomes
Our institutional review board approved this study and access to clinical data. We reviewed our institutional database that prospectively captures clinical and laboratory data on all patients who underwent first time MV surgery for IMR with or without coronary artery bypass grafting (CABG) between January 1, 1990, and December 31, 2009. After exclusion of all patients who underwent combined mitral valve procedures (except for atrial septal defect closure, tricuspid valve surgery, or MAZE procedure) and any patient who had echocardiographic evidence of structural (chordal or leaflet) mitral valve disease, a ruptured papillary muscle, post-infarction ventricular septal defect (VSD), left ventricular (LV) aneurysm, or endocarditis, we identified 393 patients. Of these patients, 164 (42%) had MVr, and 229 (58%) had MVR.
Preoperative demographics, operative variables, and postoperative outcomes were retrospectively analyzed, and multivariable regression analysis was employed to identify independent predictors of hospital mortality. Importantly, to validate the diagnosis of IMR, we conducted a detailed chart review to exclude any patient with evidence of structural (chordal or leaflet) disease of the MV, which included all preoperative cardiac imaging tests within a month of surgery, as well as the operative records and pathology reports, to exclude any patients with congenital, degenerative, rheumatic or infective mitral valve pathology.
The primary outcome was 30-day mortality. Secondary endpoints include low cardiac output syndrome (LCOS), stroke, acute kidney injury, and myocardial infarction (MI). LCOS was defined as the need for either postoperative intra-aortic balloon pump (IABP) support or sustained high-dose inotropic support. The need for inotropic support was defined as the use of epinephrine, dobutamine, milrinone, or dopamine to keep cardiac output greater than 2.2 L/min/m2 after optimizing preload and afterload and correction of all electrolyte and blood gas abnormalities.