A 61-year-old man presents for a routine clinic visit. His active diagnoses include hypertension, hyperlipidemia, and nonischemic cardiomyopathy. He was first seen two years ago, following four episodes of severe substernal chest pain.

At that time, he underwent exercise stress testing, as well as coronary angiography. Neither of these tests revealed coronary artery disease; however, they did document a transmural myocardial infarction (MI) and an inferolateral wall motion abnormality. The left ventricular ejection fraction was 30%. According to the medical record, the patient was diagnosed with an acute MI due to coronary artery spasm and was treated with b-blockers, long-acting nitrates, diuretics, and an ACE inhibitor. His condition has remained stable over the past two years, and he has been seen regularly in the cardiovascular clinic.

Today, the patient is concerned that his energy level has decreased significantly over the past six months. He now gets fatigued walking 500 feet to the end of his driveway to check his mail, and he is unable to walk uphill or climb one flight of stairs without stopping to rest. He denies peripheral edema, angina, paroxysmal nocturnal dyspnea, or orthopnea.

Medical history is remarkable for well-controlled hypertension, hyperlipidemia, and a remote MI. Family history is unknown. The patient currently smokes half a pack of cigarettes daily and has done so for 30 years. He rarely uses alcohol and denies the use of recreational drugs or herbal remedies. He has no known drug allergies. His current medications include aspirin, hydrochlorothiazide, isosorbide mononitrate, lisinopril, carvedilol, and simvastatin.

The physical exam reveals a blood pressure of 100/61 mm Hg; pulse, 80 and regular; respiratory rate, 16 breaths/min; and oxygen saturation, 98% on room air. The patient’s height and weight are 5'11" and 224 lb. The jugular venous pressure is measured at 8 cm, the lungs are clear, and the cardiac exam and remainder of his physical exam are unremarkable.

An ECG reveals the following: a ventricular rate of 75 beats/min; PR interval, 142 ms; QRS duration, 166 ms; QT/QTc, 466/520 ms; P axis, 66°; R axis, 39°; and T axis, –87°. What is your interpretation of this ECG—and, assuming he is on optimal medical management, is there another treatment that may be of benefit to this patient?

ANSWER

The correct interpretation of this ECG includes normal sinus rhythm with a left bundle-branch block (LBBB). Criteria for LBBB include a QRS duration of 120 ms or greater, a QS or rS complex in lead V₁, a monophasic R wave in leads I and V₆, and T waves that are opposite of the terminal deflection of the QRS complex.

With a history of hypertension, nonischemic cardiomyopathy, prior MI, left ventricular ejection fraction of 30%, LBBB, and New York Heart Association Class III symptoms, this patient is a candidate for a primary prevention implantable defibrillator system and cardiac resynchronization therapy (biventricular implantable cardioverter defibrillator).