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QRS slopes for ischemia monitoring in PCI recordings

Abstract:

In clinical practice ST elevation is used in the ECG to detect myocardial infarction. Additional information from the depolarization phase (QRS complex) can improve diagnosis and risk stratification of the patient. In this paper we present a study of the upward (IUS) and downward (IDS) slopes of the QRS complex as an alternative for detecting and quantifying ischemia induced depolarization changes. From ECG recordings both in a resting state (control recordings) and during PCI-induced transmural ischemia, we develop a method for quantification of IUS and IDS that incorporates dynamic ECG normalization so as to improve sensitivity in the detection of ischemia induced changes. We show that IUS and I DS present high stability at resting state, thus providing a stable reference for ischemia characterization. In PCI recordings we show that I US and IDS present maximum relative factors of change of 6.01 and 9.31, respectively, with respect to their own variability at control. We also show that the timing for the occurrence of significant changes in I US and IDS varies with lead, ranging from 30 s to 2 min after initiation of coronary occlusion. We conclude that QRS slopes offer a robust tool for evaluating depolarization changes during myocardial ischemia.