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