A 70-year-old woman presents to the heart failure clinic because of worsening exercise intolerance. She has a history of nonischemic dilated cardiomyopathy diagnosed 3 years ago. Current medications include sacubitril-valsartan, metoprolol succinate, spironolactone, empagliflozin, and furosemide. She reports excellent adherence to her medications. Despite treatment, she becomes short of breath after walking half a block and must sleep on two pillows at night. Temperature is 36.8°C (98.2°F), blood pressure is 108/66 mm Hg, pulse is 72/min, and respiratory rate is 16/min. Physical examination demonstrates elevated jugular venous pressure, bibasilar crackles, and 1+ bilateral lower-extremity edema. Laboratory studies reveal stable renal function and normal potassium levels.
Transthoracic echocardiography demonstrates the following:
Left ventricular ejection fraction: 25%
Diffuse left ventricular hypokinesis
No significant valvular disease
ECG demonstrates sinus rhythm, a left bundle branch block, and a QRS duration of 168 milliseconds.
Which of the following is the most appropriate next step in management?
The correct answer is:
A) Cardiac resynchronization therapy with biventricular pacing
This patient has symptomatic HFrEF despite optimal guideline-directed medical therapy. She has three classic findings that predict benefit from cardiac resynchronization therapy (CRT): an ejection fraction ≤35%, persistent symptoms despite medical therapy, and a left bundle branch block with a markedly prolonged QRS duration.
In left bundle branch block (LBBB), activation of the left ventricle is delayed, causing ventricular dyssynchrony. Rather than contracting simultaneously, portions of the left ventricle contract at different times, reducing cardiac efficiency and worsening systolic function. CRT uses biventricular pacing to restore coordinated ventricular contraction, improving stroke volume, symptoms, ventricular remodeling, hospitalization rates, and survival.
Answer choice B: Catheter ablation of the atrioventricular node, is incorrect.
Atrioventricular (AV) node ablation may be considered in selected patients with difficult-to-control atrial fibrillation. This patient is in sinus rhythm and has no arrhythmia requiring AV nodal intervention. The primary issue is ventricular dyssynchrony due to LBBB.
Answer choice C: Increase furosemide dosage indefinitely, is incorrect.
Increasing loop diuretics may transiently improve congestion but does not address the underlying electrical dyssynchrony causing impaired ventricular performance. Furthermore, chronic escalation of diuretic therapy does not improve survival.
Answer choice D: Long-term amiodarone therapy, is incorrect.
Amiodarone is used to treat certain atrial and ventricular arrhythmias. This patient has no documented arrhythmia. Amiodarone would not correct the conduction abnormality responsible for her worsening heart failure symptoms.
Answer choice E: Permanent right ventricular pacemaker placement, is incorrect.
Traditional right ventricular pacing can actually worsen ventricular dyssynchrony and may exacerbate heart failure in some patients. CRT specifically requires coordinated pacing of both ventricles to restore synchronous contraction.
Key Learning Point
Cardiac resynchronization therapy is indicated for patients with symptomatic HFrEF despite optimal medical therapy who have an ejection fraction ≤35% and evidence of ventricular dyssynchrony, particularly left bundle branch block with a QRS duration ≥150 milliseconds. CRT improves symptoms, reduces hospitalizations, and improves survival.
