Minimally Invasive Versus Sternotomy Approach for Mitral Valve Surgery: A Propensity Analysis

Background. Over the past decade, minimally invasive (MI) mitral valve surgery has grown in popularity. The purpose of this study was to compare both short-and long-term outcomes of mitral valve repair and replacement performed through a MI versus traditional sternotomy (ST) incision using a propensity analysis approach to account for differences in baseline risk. Methods. From January 2000 to December 2008, a total of 1,121 isolated mitral valve operations were performed at our institution (548 ST, 573 MI). Data were retrospectively collected on all patients, and a logistic regression model was created to predict selection to a MI versus ST approach. Propensity scores were then generated based on the regression model and matched pairs created using 1: 1 nearest neighbor matching. There were 382 matched pairs in the analysis for a total sample size of 764, or 68.2% of the original cohort. Major outcomes of interest included cardiopulmonary bypass time, cross-clamp time, hospital length of stay, major in-hospital complications, and both short-and long-term survival. Results. Cardiopulmonary bypass time was 117.1 +/- 2.0 minutes in the ST group and 139.7 +/- 2.6 minutes in the MI group (p < 0.0001), and cross-clamp time was 79.6 +/- 1.5 minutes in the ST group and 83.7 +/- 1.9 in the MI group (p = 0.106). The average hospital length of stay was 9.81 +/- 0.61 days among ST patients and 7.76 +/- 0.37 days among MI patients (p = 0.0043). There was no significant difference in the frequency of major in-hospital complications between groups. The mean duration of survival follow-up was 4.2 +/- 2.4 years. There was no significant difference in mortality at 30 days (p = 0.622) or 1 year (p = 0.599). In addition, there was no significant difference in long-term survival between groups (p = 0.569). Conclusions. Although minimally invasive mitral valve surgery required a slightly longer cardiopulmonary bypass time, there was no difference in cross-clamp time, morbidity, or mortality, and hospital length of stay was significantly shorter when compared with matched sternotomy control patients.