A 75-year-old woman presents to the emergency department, anxious and in severe distress, reporting “the worst case of shortness of breath I’ve ever had.” During the preceding 24 hours, she states, she felt “progressively ill,” with fevers and chills. However, she denies any episodes of chest pain. 

The patient had rheumatic fever as a child but had no cardiac or pulmonary symptoms until August 2009, when she experienced a non–ST elevation myocardial infarction (NSTEMI) while on vacation. A workup during admission for that event showed a long, tubular 80% lesion of the left anterior descending artery, no significant circumflex or right coronary artery disease, pulmonary artery (PA) pressures of 62/21 mm Hg, a mean PA pressure of 37 mm Hg, and a left ventricular ejection fraction of 70% with severe mitral regurgitation. She was treated conservatively during that admission, as surgical intervention was deemed to involve too high a risk. 

Since returning home, she has had three successive admissions for shortness of breath. All were managed by adjustment of her medications. Her medication list includes aspirin, carvedilol, valsartan, isosorbide mononitrate, furosemide, potassium chloride, and simvastatin.

Vital statistics include a height of 167 cm; weight, 62 kg; blood pressure, 156/66 mm Hg; pulse, 72 beats/min; and temperature, 39°C. Pertinent physical findings include no jugular venous distention, a grade IV/VI high-pitched holosystolic murmur, rales in all lung fields with diminished breath sounds in both bases, and cool extremities with good pulses and trace edema.

A chest x-ray reveals bilateral pleural effusions with adjacent atelectasis and patchy opacities in the right middle lobe fields. Pertinent laboratory data include normal cardiac enzyme and electrolyte levels, a serum glucose level of 201 mg/dL, a hematocrit level of 31%, and a white blood cell count of 14.21 x 10³/uL.

ECG reveals the following: a ventricular rate of 72 beats/min; PR interval, 124 ms; QRS duration, 124 ms; QT/QTc interval, 444/486 ms; P axis, 269°; R axis, –44°; and T axis, 147°. What is your interpretation of this ECG?

ANSWER
An unusual P-wave axis (isoelectric in lead I, negative in lead II) and a relatively short PR interval (normal range, 120 to 200 ms) are strongly suspicious for a junctional rhythm rather than a normal sinus rhythm. Left-axis deviation is evident from an R axis of –44°. A right bundle branch block is evident (QRS duration >100 ms, terminal R in V₁, eg, rSR’).

The T wave is typically deflected in the opposite direction of the terminal deflection of the QRS complex (discordance), but that is not the case on this ECG. A concordant T wave (deflection in the same direction as the terminal deflection of the QRS complex) is present, suggesting ischemia or myocardial infarction. This is documented by the presence of an old lateral myocardial infarction (Q waves in leads I, aVL).

The source for this patient’s symptoms upon admission was determined to be right middle lobe pneumonia.