Differential Diagnosis for Supraventricular Tachycardia with Aberrancy

• Single most likely diagnosis:
  • Supraventricular Tachycardia (SVT) with Left Bundle Branch Block (LBBB) aberrancy: This is the most likely diagnosis given the ECG findings of a narrow complex tachycardia with a rate between 160-280 bpm and the presence of LBBB pattern, which is a common form of aberrancy in SVT.
• Other Likely diagnoses:
  • SVT with Right Bundle Branch Block (RBBB) aberrancy: Although less common than LBBB aberrancy, RBBB aberrancy can also occur in SVT, presenting with a similar narrow complex tachycardia but with an RBBB pattern on the ECG.
  • Atrial Flutter with 2:1 block and LBBB aberrancy: Atrial flutter can present with a regular, rapid ventricular rate if there is a 2:1 block, and if LBBB aberrancy is present, the QRS complexes will be widened, mimicking SVT with aberrancy.
• Do Not Miss diagnoses:
  • Ventricular Tachycardia (VT): Although less common than SVT, VT is a life-threatening condition that can present with a wide complex tachycardia, which may be mistaken for SVT with aberrancy. It is crucial to distinguish between these two conditions as the treatment and prognosis are significantly different.
  • Wolff-Parkinson-White (WPW) syndrome with atrial fibrillation: In WPW syndrome, an accessory electrical pathway between the atria and ventricles can cause a very rapid and irregular ventricular rate during atrial fibrillation, which can be life-threatening if not recognized and treated promptly.
• Rare diagnoses:
  • Junctional Tachycardia with LBBB aberrancy: A rare form of supraventricular tachycardia originating from the AV junction, which can present with a narrow complex tachycardia and LBBB aberrancy if the tachycardia is of junctional origin and there is concomitant LBBB.
  • Mahaim fiber tachycardia: A rare condition involving an accessory pathway that can cause a narrow complex tachycardia, which may mimic SVT with aberrancy but typically has distinct ECG features.