Scenario: This 12-lead electrocardiogram (ECG) was obtained on a 48-year-old man who came to the emergency department with progressively worsening left lateral crushing chest pain and dyspnea of 3 hours’ duration. The patient drinks 9 beers daily, is an active smoker, and is treated for hypertension and hypercholesterolemia. His initial vital signs during prehospital transport showed a heart rate of ~110/minute and blood pressure of 151/100 mm Hg. Paramedics administered aspirin and sublingual nitroglycerin during ambulance transport, and this ECG was obtained upon arrival in the emergency department.

Sinus rhythm with Wolff-Parkinson-White (WPW) syndrome type A.

In the normal electrical conduction system, the atrioventricular (AV) node serves as a gatekeeper to regulate the propagation of signals from the atria into the ventricles. When an accessory pathway exists, ventricular activation occurs through both the AV node and the extra anatomical pathway, yielding a...

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