A 38-year-old woman calls 911 following a three-day history of shortness of breath, diaphoresis, profound orthopnea, and paroxysmal nocturnal dyspnea. Prior to the ambulance’s arrival, she decides to drive herself to the hospital and experiences an episode of syncope while waiting at a traffic light. Bystanders find her unconscious, 911 is activated, and she is transported by ambulance to the emergency department. 

Upon arrival, she is conscious but short of breath, despite 6L of oxygen delivered by facemask. She does not remember the syncopal event and did not lose bowel or bladder control. She has no prior cardiac or pulmonary ­history.

Medical history is remarkable for hypothyroidism, hypertension, and hyperlipidemia. Family history is noncontributory, as she was adopted as an infant and never knew her biological parents. She smokes half a pack of cigarettes per day, drinks alcohol socially on weekends, and denies illicit or naturopathic drug use.

Her current medications include levothyroxine (0.3 mg/d) and lovastatin (40 mg/d). She takes ibuprofen (400 mg tid) as needed for low back pain. She was prescribed a drug for hypertension; however, she cannot remember the name, only the fact that it was too expensive, so she didn’t have the prescription filled.  She is allergic to sulfa.

The review of systems is remarkable for daily headaches and chronic low back pain attributable to a motor vehicle accident five years ago. She has two children, a 6-year-old girl and a 4-year-old boy. She is certain she is not pregnant.

Physical examination reveals a blood pressure of 154/86 mm Hg; pulse, 74 beats/min; respiratory rate, 18 breaths/min; O₂ ­saturation, 98% on 6L O₂; temperature, 37.8°C; weight, 96.9 kg; and height, 165 cm. The HEENT is remarkable for exophthalmos without lid lag. The neck is supple without adenopathy, carotid pulses are 2+ and equal, and the jugular venous pressure is 7 mm Hg.

The cardiac exam is remarkable for a normal rate and rhythm and distant heart sounds with no murmurs or rubs. Auscultation of the lungs reveals bilateral rales in both bases with wheezes that clear with coughing. The abdomen is soft and nontender with no organomegaly present. The extremities are warm and well perfused with 2+ pulses bilaterally. Pitting edema is present in both lower extremities. The patient is neurologically intact without focal signs.

Pertinent laboratory data include a B-type natriuretic peptide (BNP) level of 1,076 pg/mL and a thyroid-stimulating hormone (TSH) level of 54 U/mL with a T4 of 1.7 mcg/dL. An echocardiogram reveals a left ventricular ejection fraction of 22% with a left ventricular end-diastolic dimension of 6.5 cm and an end-systolic dimension of 5.0 cm. Mild mitral and tricuspid regurgitation are also noted.

You are given the patient’s ECG, which shows a ventricular rate of 78 beats/min; PR interval, 190 ms; QRS duration, 116 ms; QT/QTc interval, 442/503 ms; P axis, 55°; R axis, –37°; and T axis, 74°. What is your interpretation?

ANSWER

The ECG is remarkable for left atrial enlargement, left-axis deviation, left ventricular hypertrophy with QRS widening, and prolonged QT interval. Left atrial enlargement is evidenced by a P wave in lead I of 0.11 seconds or more and terminal negativity of the P wave in lead V₁ of 1 mm² or more. Left ventricular hypertrophy is evident by high voltage in limb leads (R wave in lead I + S complex in lead III of at least 25 mm) or precordial leads (S complex in lead V₁ + R wave in V₅ or V₆ of 35 mm or more). A normal QRS interval is 100 ms or less; hence, QRS widening is present. A QTc interval > 380 ms in a woman with a heart rate of 78 beats/min is considered prolonged.

These findings, in conjunction with the patient’s echocardiogram and elevated BNP level, resulted in a diagnosis of an ­idiopathic cardiomyopathy, possibly as a result of her hypothyroidism.