Simple electrocardiographic criteria for rapid identification of wide QRS complex tachycardia: The new limb lead algorithm

Background: The electrocardiogram (ECG) is essential for the differential diagnosis of wide QRS complex tachycardia (WCT). Objective: The purpose of this study was to evaluate the diagnostic value of a novel ECG algorithm on the basis of the morphological characteristics of the QRS on the limb leads. Methods: The limb lead algorithm (LLA) was evaluated by analyzing 528 monomorphic WCTs with electrophysiology-confirmed diagnoses. In the LLA, ventricular tachycardia (VT) is diagnosed in the presence of at least 1 of the following: (1) monophasic R wave in lead aVR; (2) predominantly negative QRS in leads I, II, and III; and (3) opposing QRS complex in the limb leads: concordant monophasic QRS in all 3 inferior leads and concordant monophasic QRS in 2 or 3 of the remaining limb leads with a polarity opposite to that of the inferior leads. The diagnostic performance of the LLA was compared with that of the Brugada, Vereckei, and R-wave peak time (RWPT) algorithms. Results: Of 528 WCT cases, 397 were VT and 131 supraventricular tachycardia. The interobserver agreement for the LLA was excellent (κ = 0.98), better than that for the other algorithms. The overall accuracy of the LLA (88.1%) was similar to that of Brugada (85.4%) and Vereckei (88.1%) algorithms but was higher than that of the RWPT algorithm (70.8%). The LLA had a lower sensitivity (87.2%) than did Brugada (94.0%) and Vereckei (92.4%) algorithms, but not the RWPT algorithm (67.8%). Furthermore, the LLA showed a higher specificity (90.8%) than did Brugada (59.5%), Vereckei (76.3%), and RWPT (80.2%) algorithms. Conclusion: The LLA is a simple yet accurate method to diagnose VT when approaching WCTs on the ECG.