A 74-year-old woman presented with severe fatigue. The patient reported being dizzy for the past day, regardless of activity, and a feeling of impending loss of consciousness. She had a history of hypertension and diabetes mellitus. Her ongoing medications were enalapril, 5 mg per day; atenolol, 25 mg per day; and metformin, 750 mg per day.

On examination, she had a heart rate of 24 beats per minute, blood pressure of 90/40 mm Hg, respiratory rate of 20 breaths per minute, and peripheral oxygen saturation of 96% on room air. Results of urgent blood testing showed a glucose level of 242 mg per dL (13.43 mmol per L), potassium level of 6.8 mEq per L (6.8 mmol per L), and creatinine level of 3.2 mg per dL (282.88 μmol per L); other values were nearly within the reference range. Twelve-lead electrocardiography was performed (Figure 1).

Question

Based on the patient’s history and physical examination findings, which one of the following is the most likely diagnosis?

• A. BRASH syndrome.

• B. Long QT syndrome.

• C. Myocardial infarction.

• D. Sick sinus syndrome.