Stress ECG analysis for ischemic preconditioning evidence

Ischemic preconditioning is one of the most powerful means to protect myocardial muscle after a prolonged episode of ischemia. Human models related to the idea of ischemic preconditioning are still under discussion, specially when the results reported in previous studies are diverging. The current study provides a useful methodology to clarify, and support the evidence of ischemic preconditioning considering time series analysis of stress ECG derived parameters and multivariate analysis. The methodology was applied to a database composed of 14 Coronary Artery Disease (CAD) patients who underwent two consecutive stress tests within a 24-hour window. Preliminary results show that parameters obtained from the stress ECG are adequate to assess the ischemic preconditioning phenomenon. Based on both the Wilcoxon signed rank test and Fisher discriminant analysis, it is possible to observe either a tendency of the electrocardiographic parameters evaluated or a marked difference between groups of stress ECG recordings corresponding to the first and second stress tests. This analysis allows the authors to define differences between each particular stress ECG in the same patient and also differences between groups. Furthermore, comparison of results from healthy patients' stress ECG parameters, revealed that the second stress test results form a cluster that is oriented towards the healthy group cluster in the Fisher discriminant analysis.