Statistical analyses
LACI, NRI
REGRESSION
Categorical parameters are presented in absolute numbers and percentages while continuous parameters were tested for normal distribution using Shapiro–Wilk test and are reported as mean with interquartile range (IQR). For the assessment of correlations, the spearman´s rank correlation coefficient was used. Non-parametric Mann–Whitney U test was used for comparisons of continuous data sets. An optimal dichotomization cut-off value for LACI was determined using Youden’s Index. Moreover, patients with a LVEF ≤ 35% were classified as a high-risk group according to established clinical practice. To analyze occurrence of clinical endpoints the Kaplan–Meier method was applied and log-rank testing was used for assessing differences between groups. Cox proportional regression models were applied for the calculation of univariate hazard ratios (HRs) in context of MACE and mortality evaluation. Only variables with a p-value < 0.05 were included in further multivariable regression calculations. A stepwise approach with thresholds of 0.05 and 0.1 for p-values to keep or remove variables respectively was used in multivariate calculations. Due to significant correlations of LACI and LA or LV volumes only one of these parameters was included in multivariate regression models in each case. In addition, the improvement in discrimination by adding LACI to a risk prediction model containing LVEF was assessed using net reclassification improvement (NRI) and integrated discrimination improvement (IDI) measurements [