Clinical characterization by Principal Component Analysis of stress test ECG

The aim of the study is to investigate whether and how QRS-complex and T-wave heterogeneity is influenced by different cardiac risk factors and clinical data. Digital ECG during stress test was acquired in 106 patients (age 63±10 years, 45 males). Two indices obtained by Principal Component Analysis (PCA): complexity (PCA₁) and non-linear components (PCA₂) were used for the analysis of the heterogeneity of the different clinical groups. Mean, max, and standard deviation values were examined in the study. Significant difference (p<;0.01÷0.05) between PCA1 of QRS (PCA₁_QRS) was found between subgroups of patients defined according to the presence or absence of angina pectoris, diabetes mellitus, stroke and smokers. Significant difference for PCA₂_QRS was obtained in the presence of angiographically significant coronary artery disease, diabetes mellitus, positive stress test and triglycerides. For the T wave significant difference was found respectively for PCA₁_T in: myocardial infarction, angiographically significant coronary artery disease and gender and for PCA₂_T in: angiographically significant coronary artery disease, percutaneous coronary intervention and gender.