Classic Holter Manifestation of Wolff-Parkinson-White Pattern
A 27-year-old man without significant past medical history presented to the cardiology outpatient clinic for intermittent palpitations. A 24-hour Holter revealed baseline sinus rhythm with delta waves (Figure, arrows). A premature ventricular beat initiates a run of narrow complex tachycardia (Figure, arrowheads), with loss of delta wave and appearance of inverted P waves (P) indicative of retrograde atrial activation. This series of events is diagnostic of the Wolff-Parkinson-White pattern (Figure).