New electrocardiographic criteria for differential diagnosis of tachycardias with advanced QRS complexes according to the type of blockade of left bundle of His

Aim. To evaluate standard 12-lead electrocardiogram (ECG) indices for the differential diagnosis of left bundle branch block (LBBB) tachycardias.Material and Methods. The study analyses 244 ECG indices in 63 retrospective patients (85 males and 39 females aged 50±12 years) with LBBB type tachycardias. The electrophysiological study identified ventricular tachycardias (VT) (VT group, n=20), supraventricular tachycardias (SVT) with LBBB (SVT+LBBB group, n=23) or antidromic SVTs (WPW group, n=20). Unifactorial, multifactorial, and ROC analyses were performed to develop diagnostic ECG algorithms. The prognostic accuracy of the algorithms was subsequently evaluated in a prospective group of patients with LBBB tachycardias (n=57).Results. ECG signs of LBBB VTs were as follows: 1) the presence of the initial R wave in the lead aVL; 2) the absence of a split (M-shaped) R wave in the lead I; and 3) the S wave duration in the lead V1≤100 ms. For antidromic LBBB tachycardias, the ECG signs were as follows: 1) the duration of the R waves in the lead V2≥45 ms; 2) the absence of a split R waves (M-shaped) in the lead I; and 3) the duration of the R wave in the lead aVL>30 ms. The accuracy of the algorithm for diagnosis of VT with LBBB was 95% (sensitivity of 97%, specificity of 92%). The accuracy of the algorithm for diagnosis of antidromic tachycardias was 84% (sensitivity rate of 65%, specificity rate of 100%).Conclusion. Our data showed new very powerful criteria for differential diagnosis between various LBBB tachycardias even in comparison with well-known ECG algorithms of Wellens, Brugada, Griffith, Scheinman, Vereckei, Sasaki, et al.