Will His Bundle Pacing Make Cardiac Resynchronization Therapy Obsolete?
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- atrioventricular block
- bundle of His
- cardiac pacing, artificial
- cardiac resynchronization therapy
- heart failure
Although permanent cardiac pacing successfully restores a physiological heart rate in patients with atrioventricular block, it has become apparent in recent years that chronic right ventricular (RV) pacing can lead to serious adverse consequences such as adverse ventricular remodeling and heart failure. Algorithms that minimize RV pacing for patients with sinus node dysfunction or intermittent atrioventricular block are in widespread use to avoid the problems associated with chronic RV pacing. However, in patients with advanced atrioventricular block, high percentages of ventricular pacing are unavoidable.
One approach to this problem is cardiac resynchronization therapy (CRT), in which a left ventricular lead in the coronary sinus paces simultaneously or near-simultaneously with an RV lead to allow more coordinated activation of the ventricles and avoid dyssynchrony. The BLOCK HF study (Biventricular versus Right Ventricular Pacing in Heart Failure Patients with Atrioventricular Block) showed that such an approach in patients with atrioventricular block and baseline left ventricular dysfunction (left ventricular ejection fraction [EF] ≤50% and New York Heart Association [NYHA] class I–III) led to better outcomes than RV pacing, including less adverse ventricular remodeling, a lower incidence of heart failure events, and better clinical composite scores.1 CRT has also proven to be valuable in patients with systolic heart failure without atrioventricular block but with evidence of conduction system disease manifested as a prolonged QRS duration, usually left bundle-branch block. Multiple trials …