Table 2: ECG Criteria in the 2019 European Society of Cardiology Guidelines Suggest Ventricular Rather Than Supraventricular Tachycardia in Wide Complex Tachycardia.

Atrioventricular dissociation	Ventricular rate > atrial rate
Fusion/capture beats	Different QRS morphology from that of tachycardia
Chest lead negative concordance	All precordial chest leads negative
RS in precordial leads	Absence of RS in precordial leads RS >100 ms in any lead*
QRS complex in aVR	Initial R wave Initial R or Q wave >40 ms Presence of a notch of predominantly negative complex
QRS axis −90° to ± 180°	Both in the presence of right and left bundle branch block morphology
R wave peak time in lead II	R wave peak time ≥50 ms
Right bundle branch block morphology	Lead V1: Monophasic R, rsR’, biphasic qR complex, broad R (>40 ms), and a double-peaked R wave with the left peak taller than the right (the so-called rabbit ear sign) Lead V6: R:S ratio <1 (rS, QS patterns)
Left bundle branch block morphology	Lead V1: Broad R wave, slurred or notched down stroke of the S wave and delayed nadir of S wave Lead V6: Q or QS wave

*RS = beginning of R to deepest part of S. Source: Brugada et al. 2019.[¹] Reproduced with permission from Oxford University Press.