Efficacy of Cardiac Resynchronization Therapy in New York Heart Association II

History

The patient is a 66-year-old woman who first came to medical attention for her heart disease 3 years ago. She had been on a cruise when she initially noticed some functional limitation. She began to have difficulty climbing the stairs and found it necessary to use the elevator. By the end of the cruise she had pedal edema to the midcalf and had to sleep semirecumbant because of shortness of breath while lying flat.

On her return home, she went to see her family doctor, who ordered an echocardiogram. This showed an ejection fraction of 20%. There was trivial mitral regurgitation. The left ventricular mass index was 153 g/m . The left ventricular end-systolic and end-diastolic dimensions were 44 and 66 mm, respectively. An electrocardiogram (ECG) demonstrated normal sinus rhythm at 77 bpm with left bundle branch block (LBBB) and left axis deviation.

She was initially treated with a diuretic (furosemide [Lasix]) and an angiotensin-converting enzyme inhibitor (ramipril). When she became euvolemic a beta blocker was added (carvedilol) and titrated up to target doses.

She underwent a coronary angiogram, which showed no evidence of flow-limiting coronary artery disease.

Her past medical history included smoking (she stopped smoking 3 years ago, after smoking one pack per day for 20 years). She had a history of breast cancer for which she was treated with chemotherapy (including doxorubicin) and radiation. She drinks 1 to 2 glasses of wine on weekend evenings. She has no family history of cardiomyopathy.

The workup for her heart failure revealed no evidence of human immunodeficiency virus, thyroid disease, hemochromatosis, or amyloidosis. She had no recent history of viral infection.

After 9 months of therapy a repeat echocardiogram was performed and showed an ejection fraction of 30%. Her symptoms had improved such that she denied any functional limitation. An exercise stress test was performed to assess her functional ability objectively. She performed a bicycle stress test and was able to perform 3.8 metabolic equivalents. This was deemed to be below expected for her age and gender.

She was referred for a biventricular implantable cardioverter-defibrillator (ICD), but she initially refused because she felt well. During the subsequent 2 years she had one hospitalization for heart failure. At that time her weight was 5 kg over her usual dry weight. She was admitted for a total of 3 days and after intravenous diuretics was back to her baseline weight and functional status.

At a recent visit to the cardiac function clinic it was recommended again that she consider a cardiac resynchronization therapy defibrillator (CRT-D). She wished to discuss it further and was referred to a cardiac electrophysiologist.

Current Medications

The patient takes ramipril 10 mg, carvedilol 25 mg, and spironolactone 12.5 mg in the morning and carvedilol 25 mg in the evening.

Physical Examination

• BP/HR: 88/54 mm Hg (left arm, seated position)/53 bpm at rest

• Height/weight: 172.5 cm/80.5 kg

• Neck veins: 2 cm above the sternal angle, positive abdominojugular reflux

• Lungs/chest: Good breath sounds, no crepitations nor wheezes

• Heart: Normal first heart sound (S ₁ ), paradoxically split second heart sound (S ₂ ), no third (S ₃ ) or fourth (S ₄ ) heart sounds, no audible murmurs

• Abdomen: No hepatosplenomegaly, no aortic enlargement

• Extremities: Warm, well perfused; grade 2 pedal edema

Laboratory Data

• Hemoglobin: 139 g/L

• Hematocrit/packed cell volume: 0.43%

• Mean corpuscular volume: 88 fL

• Platelet count: 219 × 10 ³ /µL

• Sodium: 140 mmol/L

• Potassium: 5.6 mmol/L

• Creatinine: 115 μmol/L

• Blood urea nitrogen: 7 mmol/L