Narrow vs Wide QRS Complex Tachycardia in a Patient With Wolf-Parkinson-White Syndrome

Scenario: A 72-year-old woman arrived at the emergency department via ambulance with chest tightness and dizziness, which had started 7 hours before she called 911. The patient’s history included coronary artery disease, Wolf-Parkinson-White (WPW) syndrome, hypertension, and diabetes mellitus. The 12-lead electrocardiograms (ECGs) obtained during ambulance transport and in the emergency department were nonspecific for myocardial ischemia, and the initial high-sensitivity cardiac troponin (hs-cTn) was 9 ng/L (normal, <14 ng/L). Because the patient was stable, she was admitted to the cardiac step-down unit to rule out acute coronary syndrome (ACS). Her admitting blood pressure was 114/68 mm Hg, the rhythm was sinus at a rate of 97 beats per minute (bpm), and the oxygen saturation was 98% without supplemental oxygen. Four hours after admission, the patient reported feeling her heart “skipping beats and racing,” which were different symptoms reported at admission. Simultaneously an atrial fibrillation alarm was generated at...