Contributor: Peter Bakes, MD Educational Pearls: Tachycardia describes a heart rate of >120 beats per minute Wide Complex describes a QRS duration of >120 ms or 3 small boxes on a standard EKG The major differential for a wide complex tachycardia is Ventricular Tachycardia (VT), aka “V Tach”, or Supraventricular Tachycardia (SVT) with Aberrancy   SVT alone is a narrow complex tachycardia, but as rate increases a right or left bundle branch block pattern may emerge, creating SVT with Aberrancy seen as a wide complex on EKG It is important to distinguish the rhythms as treatment for stable VT differs from treatment(s) for stable SVT  Brugada Criteria is an algorithm for determining if wide complex tachycardia is VT with a high degree of sensitivity and specificity. Following is a simple ED approach based on brugada criteria to determine VT on EKG. If either condition is true, suspect and treat VT:   Concordance: All precordial leads have QRS complexes that are either all positive or all negative.  R-S interval: >100 ms in any one precordial lead.  Also note that VT is more common in patients who are elderly and/or have cardiac comorbidities of ischemic or structural heart disease References Reithmann C. Tachykardien mit breiten QRS-Komplexen [Differential diagnosis of wide QRS complex tachycardia]. MMW Fortschr Med. 2019;161(13):48-56. doi:10.1007/s15006-019-0022-x Ding WY, Mahida S. Wide complex tachycardia: differentiating ventricular tachycardia from supraventricular tachycardia. Heart. 2021;107(24):1995-2003. doi:10.1136/heartjnl-2020-316874 Brugada P, Brugada J, Mont L, Smeets J, Andries EW. A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex. Circulation. 1991;83(5):1649-1659. doi:10.1161/01.cir.83.5.1649   Summarized by Kirsten Hughes, MS4 | Edited by John Spartz, MD & Erik Verzemnieks, MD   The Emergency Medical Minute is excited to announce that we are now offering AMA PRA Category 1 credits™ via online course modules. To access these and for more information, visit our website at https://emergencymedicalminute.org/cme-courses/ and create an account.  Donate to EMM today!