Evaluation of the QRS-T angle using the high-resolution 64-lead electrocardiography

The aim of the study was to evaluate the influence of the number of electrocardiogram (ECG) leads on the diagnostic value of TCRT (spatial QRS-T angle) parameter (12 standard ECG leads and 61 surface ECG leads were used). The TCRT parameter, which describes the spatial QRS-T angle, is a useful indicator of the risk of ventricular tachycardia (VT) and sudden cardiac death (SCD). It is usually calculated from standard 12 leads ECG.

The TCRT parameter was calculated from the three virtual orthogonal leads obtained by singular value decomposition of the averaged ECG signals. Sensitivity and specificity of TCRT parameter in identifying VT patients were tested on two groups of patients after myocardial infarction: 13 non - VT patients and 30 VT patients. Additionally 17 healthy volunteers were studied as a control group.

Mean value (+/-SD) of TCRT parameter calculated for 61 leads was -0.80+/-0.27 for VT patients and 0.27+/-0.46 for non VT patients. For 12 standard leads TCRT mean value was -0.80+/-0.22 for VT patients and 0.27+/-0.49 for non VT patients. Sensitivity for VT patients was 87% (61 leads) and 83% (12 leads). Specificity in non-VT group was 100% for both lead sets.

Results of the study show distinct differences in the TCRT parameter values between VT patients and non VT patients for both lead sets. The sensitivities of the TCRT parameter obtained for 61 leads and for 12 standard leads were comparable.