Statistical Analysis
Continuous data are presented as mean ± standard deviation for normally distributed variables or median [interquartile range (IQR)] for non-normally distributed variables. Categorical data are displayed as number (percentage). Kaplan Meier analysis was used to evaluate one-year survival. A probability analysis was conducted to identify estimated rates of operative mortality based on CPB time over 300 minutes. Statistical analyses were performed using SAS version 9.2 software (SAS Institute, Cary, NC).