Differential Diagnosis of Wide QRS Tachycardia by Electrocardiogram

Background and Objectives:The differential diagnosis of a regular tachycardia, with a wide QRS complex (≥120 msec) on the 12-lead electrocardiogram (ECG), remains an important challenge. Despite the information available on electrocardiography in patients with ventricular tachycardia (VT) and supraventricular ventricular tachycardia, with aberrant conduction or pre-existed bundle branch block (wide-QRS SVT);the data from Korean is limited. The purpose of this study was to report on the differential diagnostic criteria. Subjects and Methods:The clinical and electrocardiographic characteristics of 150 patients (65.8%) with VT, and 78 (34.2%) with wide-QRS SVT, were evaluated. Results:An atrioventricular (AV ) dissociation was found in 44.7% (67/150) of the VTs, which is very useful in differential diagnosis. In the RBBB patterns, a monophasic R, or a biphasic, wave (QR, RS), in the V1 lead, were present in 49.0 and 40.6% of VTs, respectively, and an R/S ratio of less than 1, in the V6 lead, was present in 89.6% of VTs. In the LBBB patterns, the duration of the R wave (≥30 msec), the interval from the Q wave to the nadir of the S wave (≥70 msec) and the notching of the S wave, in the V1 lead, were present in 61.1, 87.0 and 31.3% of VTs, respectively. When an algorithm, using the AV dissociation and morphological criteria for a VT in the V1 and V6 leads, was tested for differentiation, the sensitivity and specificity were 96.7 and 93.6%, respectively. Conclusion:A more accurate, correct, diagnosis of wide-QRS tachycardia can be made by using a stepwise approaching method consisting of AV dissociation and morphological criteria for VT in the V1