QRS complex duration variability assessment using Dynamic Time Warping and Piecewise Linear Approximation

The Signal Averaged Electrocardiography (SAECG) is a widely used technique to improve Signal to Noise Ratio (SNR) in ECG records, taken in account that these records are quasi-steady. Sometimes patient´s physiology may alter those quasi-steady characteristics in heartbeats that are assumed in the averaging. This paper evaluates the QRS complex duration (QRS_d) as a parameter for measuring heartbeat-alignment, using both Derivative Dynamic Time Warping (DDTW) and Piecewise Linear Approximation (PLA). Results show that using those algorithms it is possible to reach acceptable SNR, significant QRS_d variability reduction, and a decrease of the heartbeat number needed for the averaging.