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Time-Warping Based End-of-T-Wave Shape Marker Reflects Repolarization Changes During Ischemia

Abstract:

This work proposes to use a warping-based T-wave morphology index, dw, estimated only in the T-wave peak-to-end interval, to capture ischemia-induced dispersion of repolarization, avoiding the influence of ST segment elevation/depression. ECG recordings acquired during elective balloon percutaneous coronary intervention (PCI) were analyzed, together with their baseline recordings. A dw series was obtained by comparing the morphology of Mean Warped T wave peak-to end intervals (MWTPE) along the recordings with a reference MWTPE. A relative marker, RdPCA, normalizing the dw changes during PCI relative by the magnitude of the change during baseline recordings, was used to quantify the relative morphological variations generated by ischemia. dw changes during PCI followed a well marked gradual increasing trend as inflation time progressed reaching at the occlusion end a median RdPCA value of 9.44 ms, (range from 1.01 to 80.74). During baseline recordings dw remained stable with median RdPCA value of 1.00 ms, (range from 0.03 to 2.93 ms). Repolarization changes achieved RdPCA > 1,2, 5, 10 during PCI in 94.1%, 85.11%, 64.4% and 48.5% of patients, respectively, being significantly higher than its corresponding control recordings. In conclusion, the dw marker is able to quantify ischemia-induced repolarization dispersion changes in a robust manner independent of the ST changes.