What question did this study set out to answer?

This report aims to assess an unusual case of wide complex tachycardia during exercise stress testing.

March 12, 2026Open Access

Exercise induced Irregular Wide QRS Tachycardia with Right Bundle Branch Block Morphology and Extreme QRS Axis Deviation

Key Result

Exercise stress testing revealed irregular wide complex tachycardia with right bundle branch morphology, raising concerns for either atrial fibrillation or left ventricular tachycardia.

Key Points

This report aims to assess an unusual case of wide complex tachycardia during exercise stress testing.
Clinical evaluation of a 29-year-old woman
Exercise stress testing to observe cardiac rhythms
Differential diagnosis via ECG analysis
Identified irregular wide complex tachycardia with right bundle branch morphology
Discussed potential diagnoses including atrial fibrillation and ventricular tachycardia
Noted extreme QRS axis deviation during the event

Structured PICO

Population

1 active woman, age 29, presenting with irregular wide complex tachycardia with right bundle branch morphology and extreme QRS axis during exercise stress testing.

The differential diagnosis of exercise-induced irregular wide complex tachycardia with RBBB morphology includes AF with aberrancy/pre-excitation and specific left ventricular tachycardias.

Main Result

Absolute Event Rate: 0% vs 0%

Abstract

A 29-year-old active woman was referred for evaluation following the development of an irregular wide complex tachycardia with right bundle branch morphology and extreme QRS axis during exercise stress testing. Two main alternative diagnoses are discussed: a) atrial fibrillation with either aberrancy or pre-excitation; b) left ventricular tachycardia originating from the Purkinje system including left posterior fascicle versus posteromedial papillary muscle.