**2.7 Statistical analysis**

Statistical analyses wee conducted using SPSS software version 13. All values were expressed as means and standard deviations. Two-tailed student's-t test was performed to compare changes in DDT and P1/2T, considering p<0.05 as statistically significant. Assessment of clinical utility of flow parameters was done by calculating sensitivity, specificity, positive and negative predictive values as well as diagnostic accuracy. Correlation coefficients and their p value were calculated to evaluate the relation of LAD flow parameters with LV systolic function parameters pre-discharge (5 days after PCI).
