Assessing QT-RR interval hysteresis in 12-lead electrocardiograms

The amount of QT-RR interval hysteresis accumulated during the load and recovery phases of exercise stress test reflects the degree of exercise induced myocardial ischemia. Therefore the evaluation of hysteresis from 12-lead ECG (12-SL) is an important practical modality for the assessment of severity of coronary artery disease. Commercial QT and RR waveform analyzers are regularly subjected to interval detection artifacts which prevent reliable estimation for the magnitude of QT-RR hysteresis in one or multiple leads. We present a new signal processing technique which overcomes this deficiency. It quantifies the level of faulty interval measurements and using a threshold eliminates the need to process potentially corrupt leads.