A 41-year-old woman is admitted to the hospital after successful resuscitation from sudden cardiac death. She was in her usual state of good health until one month ago, when she had a flulike illness. Her principal symptoms included fatigue and malaise, but no chest pain, shortness of breath, near-syncope, or syncope.

Her husband witnessed her cardiac arrest, called 911, and promptly initiated cardiopulmonary resuscitation. The paramedics arrived 10 minutes later, documented ventricular fibrillation with the automatic external defibrillator, and successfully defibrillated the patient with one 200-J shock.

Upon the patient’s arrival at the hospital, a cardiac catheterization is performed and identifies no coronary artery disease. A cooling protocol is initiated via an inferior vena cava cooling catheter, and she fully recovers all neurologic function. An echocardiogram reveals a left ventricular ejection fraction of 40% but no other significant cardiac abnormalities.

At the time of admission, the patient was taking no medications. She was started on b-blocker therapy (metoprolol 25 mg bid) and has received two doses. Her blood pressure is 150/80 mm Hg, her heart rate is 80 beats/min, and her respiratory rate is 14 breaths/min. The remainder of her physical exam is unremarkable. 

A baseline ECG, obtained in preparation for placement of an implantable cardioverter defibrillator, shows the following: a ventricular rate of 80 beats/min; PR interval, 120 ms; QRS duration, 106 ms; QT/QTc interval, 414/477 ms; P axis, 55°; R axis, 63°; and T axis, 253°. What is your interpretation of this ECG?

ANSWER

The ECG shows sinus rhythm with frequent premature ventricular complexes in a pattern of bigeminy. The bigeminal pattern is monomorphic, with a fairly narrow QRS duration of approximately 140 ms, and is superiorly directed with a right bundle branch pattern consistent with a midapical inferior origin in the left ventricle. Other findings include voltage criteria for left atrial enlargement (P-wave duration > 120 ms) and T-wave inversions in the inferior limb leads.

The metoprolol dose was increased to suppress the patient’s premature ventricular complexes, and she underwent an uneventful implantation of a cardioverter defibrillator system.