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.