Wide QRS Tachycardias With Syncope: Two for One?

The differential diagnosis of wide complex tachycardias can be challenging but is essential for correct diagnosis and treatment.

We describe the case of a patient presenting with 2 wide complex tachycardias, both with left bundle branch block-like morphology, left superior axis, and slurred onset. The diagnosis of pre-excited atrial flutter with 1:1, respectively, 2:1 conduction was made after careful analysis of the tracings. Electrocardiogram in sinus rhythm showed short PR but inapparent pre-excitation. An invasive electrophysiological study confirmed an anterograde-conducting right postero-septal pathway, and radiofrequency ablation was performed successfully.

Pre-excited atrial flutter may mimic ventricular tachycardia and represents an important diagnostic challenge with significant therapeutic implications.

This case highlights the importance of correct differential diagnosis of wide complex tachycardias, as management strategies differ substantially. Careful electrocardiogram analysis is essential, as pre-excitation may be inapparent in sinus rhythm even for high-risk accessory pathways.