Introduction
Ischemic mitral regurgitation (IMR) is a frequent complication of
coronary artery disease, which is associated with increased left
ventricular (LV) dysfunction and mortality [1, 2]. Most experts in
mitral surgery advocate for concomitant correction of more than moderate
IMR during coronary bypass surgery. However, the choice of mitral valve
repair (MVr) or mitral valve replacement (MVR) is controversial
[3-5]. Mitral valve repair has been associated with lower hospital
mortality and greater late survival compared to replacement in patients
with degenerative mitral valve disease [6, 7]. In contrast, the
benefits of mitral valve (MV) repair compared to replacement in patients
with IMR are not as well defined. Several retrospective studies
suggested lower operative mortality and better long-term survival with
repair compared to replacement in patients with IMR [8-15]. However,
these studies are largely limited by inherent selection bias in favor of
repair. Indeed, a recent randomized controlled trial (RCT) [16],
which compared MV repair versus replacement in patients with IMR showed
equivalent operative mortality and short-term survival but better
freedom from recurrent mitral regurgitation (MR) with MV replacement.
The purpose of this study is to compare mortality and major morbidities
after MV repair or replacement for IMR while accounting for all known
confounders using rigorous regression methodology with validation of
multivariable analysis by bootstrapping, and evaluation of the
regression model for discrimination, calibration, and multicollinearity.