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.