Planned Analysis: Descriptive statistic is applied to all clinical parameters. All the 3 cycle lengths out of the stress ECG are compared individually with the ERP-AP from the invasive EPS. If there is an average from the cycle length, this would be compared with the ERP-AP as well. And then we compare whether the difference between the cycle length and the ERP-AP is similar in a group of patients (high/low risk) or even in all patients.