Cardiac Resynchronization Therapy in a Patient with QRS Duration Between 120 and 150 Milliseconds

History

This patient had a history of lymph node tuberculosis during childhood, thyroid carcinoma (treated surgically and with radiotherapy), and depressive disorders.

A normal electrocardiogram (ECG) was recorded 20 years earlier at the time of the thyroidectomy. However, a progressive left bundle branch block (LBBB) pattern appeared with a QRS duration of 120 and 135 ms, 8 and 2 years earlier, respectively. Transthoracic echocardiography was performed 2 years earlier and showed normal left ventricular ejection fraction (LVEF) of 60%.

Current Medications

The patient is currently taking levothyroxine 75 mcg daily.

Current Symptoms

Over a 1-year period, the patient progressively experienced exercise intolerance, weight gain related to lower extremity edema, and shortness of breath (New York Heart Association [NYHA] class III). Treatment by ramipril, bisoprolol, and furosemide was initiated without significant efficacy. She was then hospitalized for a first episode of congestive heart failure.

Physical Examination

• BP/HR: 115/70 mm Hg/80 bpm

• Height/weight: 165 cm/80 kg (+10 kg in contrast to weight)

• Neck veins: Jugular veinous distention

• Lungs/chest: Shortness of breath (NYHA class III), increased breathing rate, crackles throughout the lung field

• Heart: Regular heart sounds, no murmurs detected

• Abdomen: No ascites detected, hepatojugular reflux observed when pressing over the liver

• Extremities: Lower extremities edema (ankles, legs)

Laboratory Data

• Hemoglobin: 11 g/dL

• Hematocrit/packed cell volume: 40%

• Mean corpuscular volume: 90 fL

• Platelet count: 280 × 10 ³ /µL

• Sodium: 138 mmol/L

• Potassium: 4.1 mmol/L

• Creatinine: 85 μmol/L

• Blood urea nitrogen: 5 mmol/L

Electrocardiogram

Findings

The ECG showed sinus rhythm to be 80 bpm, normal atrioventricular conduction (PR interval, 160 ms), typical LBBB with a QRS duration of 135 ms, and a QRS axis of −35 degrees ( Figure 4-1 ).