Detection of left ventricular systolic dysfunction in patients with ischemic heart disease using spatial and frontal QRS-T angles of the electrocardiogram

Aim. To evaluate the possibilities of the spatial QRS-T angle (sQRS-Ta) and the frontal QRS-T angle (fQRS-Ta) to detect low left ventricular ejection fraction (LVEF) in patients with chronic coronary heart disease. Materials and methods. We analyzed the data of 287 patients with chronic coronary artery disease, in 80 cases complicated by chronic heart failure with low LVEF. fQRS-Ta was calculated as absolute value of the difference between the frontal plane QRS and T axes. sQRS-Ta was calculated using the synthesized vectorcardiogram as a spatial angle between the integral QRS and T vectors. Results. The fQRS-Ta values in the group were 70 [25; 141]°. sQRS-Ta values in the group were 96 [55; 148]°. There were correlations between fQRS-Ta and LVEF (r=-0.58; p0.0001) and sQRS-Ta with LVEF (r=-0.63; p0.0001). According to the ROC analysis, fQRS-Ta with a threshold value of 90° made it possible to identify patients with LVEF≤40% with a sensitivity of 85% and a specificity of 75% (area under the ROC curve 0.85±0.03) and patients with LVEF≤35% with 87% sensitivity and 69% specificity (area under the ROC curve 0.84±0.04). sQRS-Ta with a threshold value of 125° made it possible to identify patients with LVEF≤40% with a sensitivity of 86% and a specificity of 82% (area under the ROC curve 0.89±0.03) and patients with LVEF≤35% with sensitivity 93% and specificity 76% (area under the ROC curve 0.89±0.02). Conclusion. In patients with chronic coronary artery disease, as the LVEF decreases, the frontal and spatial angles between the QRS and T vectors increase. These indicators with sufficiently high sensitivity and specificity make it possible to identify patients with reduced LVEF among patients with chronic coronary artery disease.