COMPARATIVE ANALYSIS OF MORPHOLOGICAL CRITERIA FOR DIFFERENTIAL DIAGNOSTICS OF WIDE QRS COMPLEX ARRHYTHMIAS WITH LEFT BUNDLE BRANCH BLOCK MORPHOLOGY
Authors: Budanova M. A. , Chmelevsky M. P. , Treshkur T. V. , Tikhonenko V. M. 
Published: February 2020

Introduction. Determination of ventricular and supraventricular arrhythmias with left bundle branch block morphology (LBBB) seems to be one of the most complex diagnostic tasks when P waves are not clearly identifiable on 12-lead ECG. Previously described criteria for differential diagnosis of wide QRS arrhythmias had low accuracy especially for patients from various clinical groups and also those taking antiarrhythmic drugs. When patient’s clinical data, medical history or physical examination results are not available the number of misdiagnosis may increase leading to improper treatment. Therefore, development of new temporal and amplitude based characteristics of wide QRS complex arrhythmias with LBBB morphology in patients of any clinical groups is an important task.Methods. Twenty-eight consecutive patients with wide QRS premature beats and LBBB morphology identified by 24-hour and long-term ECG monitoring (ZAO “INCART”, Russia) were enrolled in the study. Fourteen patients had premature atrial contractions (PAC) and fourteen patients had premature ventricular contractions (PVC) during sinus rhythm. For each patient 10 typical single wide QRS complexes in 12 ECG leads were analyzed. The duration of QRS complexes, time intrinsic deflection (TID) and electrical axis of the heart were determined automatically in 12 leads ECG using KT Result 3 software (ZAO “INCART”, Russia). The experts assessed morphology of the QRS complexes and transition zone location in leads V1-V6. ROC analysis with optimal cut-off value level evaluation as well as calculation of sensitivity (SV), specificity (SP) and diagnostic accuracy (ACC) were performed for qualitative and quantitative assessment of diagnostic value of PAC and PVC amplitude and temporal characteristics. Comparison of diagnostic values of wide QRS complex morphological and temporal criteria was performed based on the AUC difference and the corresponding p-value assessment.Results. The results of study found out that V5, V1 leads were more informative for assessment of QRS complex morphology and duration while V1 and V4 leads were more informative for TID calculation in differential diagnosis of wide QRS complexes arrhythmias with LBBB morphology. PAC with aberrant conduction had the following characteristics: TID < 68 ms in V1 lead and TID < 62 ms in V4 lead; QRS < 136 ms; transition zone in the leads V5, V6; QS, rS or RS complexes (with S> R) with low-amplitude r/R waves in leads V1-V4; electric axis of the heart less than 80° in standard leads. In all cases PVCs were characterized by QRS > 160 ms and TID > 88 ms in V1-V6 leads.Conclusions. New various criteria which can improve differential diagnosis of wide QRS complexes with LBBB morphology were identified in this study. These criteria should be tested in a larger group of patients with various forms of wide QRS complex arrhythmias and different PVC localizations including information of structural heart diseases due to the small sample size in this study.Conflicts of Interest: Viktor M. Tikhonenko - CEO (Director General) of the Institute of Cardiology Technics (INCART), Saint-Petersburg, Russia.