A 60-year-old man is found by paramedics, unresponsive, in an alley just outside a liquor store. The patient is brought to the trauma center with severe neurologic impairment and evidence of facial trauma. Vital signs include a heart rate of 51 beats/min; blood pressure, 110/60 mm Hg; respiratory rate, 13 breaths/min; and rectal temperature, 26.5°C (79.7°F).

An ECG, obtained after the patient has been intubated, shows the following: a ventricular rate of 51 beats/min; PR interval, 134 ms; QRS duration, 94 ms; QT/QTc interval, 552/508 ms; P axis, 45°; R axis, 86°; and T axis, 94°. Besides bradycardia, what abnormality is present?