Assessing Tachydysrhythmia When P-waves Are Present: Challenges and Pitfalls

A 69-year-old female presented to the emergency department with a two-hour history of persistent palpitations. An ECG showed a highly regular narrow QRS tachycardia with P waves. She was ultimately diagnosed with focal atrial tachycardia after an adenosine challenge. Focal atrial tachycardia is a regular, narrow complex, supraventricular tachycardic rhythm that is often paroxysmal and self-resolving. When this rhythm persists, it can eventually lead to tachycardia-induced cardiomyopathy. Narrow QRS complex tachycardia has a broad differential that encompasses many benign and dangerous rhythms. This report highlights the challenges and potential diagnostic pitfalls that can occur while trying to diagnose and evaluate tachydysrhythmias with presenting P-waves. We discuss the management strategies and propose a diagnostic algorithm to aid in the diagnosis of tachydysrhythmias.