A 75-year-old woman presents to her primary care provider with a history of episodic lightheadedness. She has never experienced syncope. Her only history is hypertension for which she takes a beta-blocker and hydrochlorothiazide. A 12-lead ECG is obtained (ECG A) and this prompts an admission to the hospital. Beta-blocker therapy is discontinued.
Figure 1. ECG A. Courtesy of Philip J. Podrid, MD.