Q-onset and T-end delineation: assessment of the performance of an automated method with the use of a reference database.

The aim of the study is to assess the performance of an automated method for Q-onset and T-end delineation, as well as QT measurement with the use of a 'gold standard' of a manually created reference database. The data to be used comprise 548 recordings of the PTB Diagnostic ECG Database. The ECG signals are preprocessed, suppressing power-line interference, electromyographic noise and baseline drift according to our previously published investigations, guaranteeing accurate Q-onset and T-end locality preservation. Our method for automatic detection of Q-onset and T-end is based on the minimum value of the angle between two segments having a common mid point and equal lengths of 10 ms. The minimum of the angle is searched in defined time intervals delimited separately for the Q-onset and T-end. All measurements are performed on lead II only. Mean +/- standard deviations are obtained for 95% of the recordings: -0.08 +/- 2.71 for Q-onset, 5.10 +/- 9.22 for T-end and 4.40 +/- 9.93 for QT interval, as well as for 100% of the recordings: 0.46 +/- 4.84 for Q-onset, 1.28 +/- 16.75 for T-end and 0.83 +/- 16.67 for QT interval.