BACKGROUND: The differential diagnosis of arrhythmias with wide QRS complexes is still a big challenge in clinical practice. One approach is to estimate the speed of excitation propagation through the ventricular myocardium using the electrocardiogram (ECG). This estimation is based on the ratio of the amplitudes of the initial and final parts of the QRS complex, specifically using the slow conduction index algorithm calculation.
AIM: The aim of this study was to investigate the use of a novel slow conduction index calculation in the differential diagnosis of arrhythmias with wide QRS complexes and to perform a detailed comparative analysis of its diagnostic value in all 12 ECG leads, evaluating and comparing the diagnostic accuracy of the obtained values.
MATERIALS AND METHODS: The study included 280 single wide QRS complexes with left bundle branch block (LBBB) detected during one-day and multi-day ECG monitoring in randomly selected 28 patients. A comparison of the original 12-lead ECG and individual scalable ECG graphs for selected leads was carried out. ROC analysis was used for a qualitative and quantitative assessment of diagnostic significance, based on sensitivity (Sn), specificity (Sp), and diagnostic accuracy (Acc).
RESULTS: The diagnostic value of the slow conduction index decreased in the following order across all 12 leads: aVL, V2, aVF, V5, III, V1, V4, II, aVR, V6, V3, and I. The first six ECG leads had Acc values consistently above 90%, gradually decreasing in the next six leads from 89% to 67%, respectively (p < 0.001 for all leads).
CONCLUSION: The study highlights the importance of a comprehensive approach to the analysis of the QRS complex and the need for a consistent and detailed analysis of the existing criteria for the differential diagnosis of arrhythmias with wide QRS complexes in different clinical groups of patients.