Statistical analysis
The statistical analyses were performed with SPSS software, version 21.0
(SPSS Inc., Chicago, IL, USA). The summary statistics are presented as
frequencies and percentages for categorical values, as the means and
standard deviations for normally distributed continuous values and as
medians with quartiles for nonnormally distributed continuous variables.
Comparisons between the groups were performed with Student’s unpaired t
test or the χ2 test. Probability values of less than
0.05 were considered to be statistically significant. The influence of
different parameters on 30-day mortality was analyzed using multiple
logistic regression analyses with backward elimination. The results of
the logistic regressions are presented as odds ratio (OR) with
confidence intervals. The possible risk factors (demographics,
echocardiographic measurements, vessel involvement, laboratory results,
procedure time and extracorporeal circulation time) included in the
logistic regression analysis were analyzed using receiver-operating
characteristic (ROC) curves to obtain diagnostic cutoff values, as well
as specificity and sensitivity.