Table 1: Differential Diagnosis of Wide QRS Tachycardias.

Wide QRS (>120 ms) Tachycardias

Regular: Ventricular tachycardia/flutter Ventricular paced rhythm Antidromic AV re-entrant tachycardia Supraventricular tachycardias with aberration/bundle branch block (pre-existing or rate-dependent during tachycardia) Atrial or junctional tachycardia with pre-excitation/bystander accessory pathway Supraventricular tachycardia with QRS widening due to electrolyte disturbance or antiarrhythmic drugs Irregular: AF or atrial flutter or focal atrial tachycardia with varying block conducted with aberration Antidromic AV re-entrant tachycardia due to a nodo-ventricular/fascicular accessory pathway with variable VA conduction Pre-excited AF Polymorphic VT Torsades de pointes VF Occasionally, AF with very fast ventricular response may apparently resemble a regular narrow-QRS tachycardia.

AV = atrioventricular; VA = ventriculoarterial; VT = ventricular tachycardia. Source: Brugada et al. 2019.[¹] Reproduced with permission from Oxford University Press.