In HF, what device therapy is indicated for patients with LV conduction delay and reduced EF to improve synchrony?

• A. Implantable cardioverter-defibrillator (ICD).
• B. Left ventricular assist device (LVAD).
• C. Cardiac resynchronization therapy (CRT).
• D. Pacemaker only without atrioventricular optimization.

Answer: (C)

When heart failure with reduced ejection fraction is accompanied by electrical dyssynchrony from left ventricular conduction delay, coordinating the timing of both ventricles can substantially improve pumping efficiency. Cardiac resynchronization therapy uses pacing leads in both the right and left ventricles to synchronize their contractions, often correcting the abnormal timing seen with a wide QRS, such as left bundle branch block. This resynchronization boosts stroke volume, reduces wall stress, can reverse adverse remodeling, and tends to improve symptoms, exercise capacity, and hospitalization rates, with potential survival benefits in appropriately selected patients.

The other devices address different problems. An implantable cardioverter-defibrillator reduces the risk of sudden cardiac death due to malignant arrhythmias but does not correct the mechanical dyssynchrony, so it doesn’t directly improve synchrony. A left ventricular assist device provides mechanical support for advanced heart failure but doesn’t correct conduction delays or synchronize ventricular contraction. A pacemaker alone, without atrioventricular optimization or biventricular pacing, improves rate control but does not correct the dyssynchrony that CRT targets.