A 68-year-old woman presents following an episode of presyncope that occurred while she was changing clothes to exercise. She reports feeling light-headed but denies loss of consciousness, chest pain, or palpitations. She states she did not feel ill earlier in the day. After she leaned against the wall for several seconds, the sensation passed, and she continued with her exercise regime. The symptoms did not recur during exercise, but the patient tired early and slept for “a long time” after returning home.

She has had similar, scattered episodes during the last several years and underwent an extensive cardiac work-up at another facility, given her family history: Her father and two brothers died suddenly at ages 64, 57, and 60, respectively. Her 57-year-old sister experiences similar episodes of presyncope.

In the patient’s prior cardiac workups, a Holter monitor demonstrated predominantly normal sinus rhythm with occasional premature ventricular contractions, one asymptomatic episode of nonsustained ventricular tachycardia (VT), and several episodes of an atrial tachycardia that were also asymptomatic. The duration of the nonsustained VT was 12 beats, with a maximum rate of approximately 150 beats/min. It appeared to accelerate from onset to offset.

An echocardiogram showed normal left ventricular cavity size, a normal left ventricular ejection fraction of 66.7%, a normal right ventricular size and function, and normal valves. On a stress echocardiogram, the patient exercised for seven minutes and 50 seconds on a standard Bruce protocol. She had an early rise in her heart rate and a peak heart rate of 160 beats/min at stage 3. Her peak blood pressure was 170/80 mm Hg, and there were no ST-segment changes during exercise. At peak exercise, there was no evidence of regional wall motion abnormalities, and there was normal augmentation of left ventricular contractility with exercise.

Medical and surgical histories are unremarkable. The patient does not have diabetes, hypertension, or hypercholesterolemia. She does not smoke and had surgical menopause at the age of 45. Her only medication is metoprolol (50 mg/d).

On physical exam, her weight is 131.4 lb, blood pressure is 126/76 mm Hg, and pulse is 62 beats/min. Cardiovascular and pulmonary exams are normal.

An ECG shows the following: a ventricular rate of 62 beats/min; PR interval, 132 ms; QRS duration, 76 ms; QT/QTc interval, 416/422 ms; P axis, 59°; R axis, 55°; and T axis, 75°.

What is your interpretation of this ECG—and, based on the patient’s history, is there anything else that should be added to her list of problems?