Abstract 15847: Detection of Stress-Induced Myocardial Ischemia by Imaging Using Novel Spectroscopic Analysis of Pre-Exercise 12-Lead ECG
Under conventional interpretation, the resting ECG is a required but nondiagnostic step in ischemia screening and evaluation. We hypothesize that spectroscopic analysis for microdamage in materials science is applicable toward the ST segment of pre-exercise 12-lead ECGs to enable detection of chronic ischemia in patients undergoing stress myocardial perfusion imaging (MPI) testing. The study included pre-exercise ECG data retrospectively and sequentially collected from 500 patients who tested positive and 500 patients who tested negative for ischemia by MPI. For each lead of each ECG collected, the segment from the J-point to the peak of the T loop (JT) was isolated, corrected for heart rate variation, and averaged to reduce artifacts. Frequency-domain harmonics were generated from the processed JT segments by cosine transform. In each of the 12 ECG leads, a measurement of signal heterogeneity, termed "Q parameter", was computed from a ratio of the harmonics. Also collected were concurrent diagnostic results from MPI examination that characterized ischemia as being negative (MPI-0) or positive (MPI-1) for each vascular territory. The grouping by MPI-0 and MPI-1 at each vascular territory and the entire myocardium by each Q parameter was evaluated by Mann-Whitney U and Kolmogorov-Smirnov tests, with statistical significance defined by p < 0.05. The accuracy of prediction was estimated by nonlinear predictors of MPI-0 or MPI-1 built for each territory and the entire myocardium, where 800 data sets were randomly selected as training sets, and the remaining 200 as testing sets. For each territory and the entire myocardium, the separate grouping of MPI-0 and MPI-1 were statistically significant for Q parameters at leads specific to the territory, and the nonlinear model showed resting ECG prediction of stress imaging results in ROC analysis (Figure). In conclusion, spectroscopic analysis of the resting ECG is capable of detecting subsequent stress-induced ischemia.
- © 2012 by American Heart Association, Inc.