For the past two decades, catheter ablation stole most of the excitement in electrophysiology. Cardiac pacing was seen as necessary but boring. His-bundle pacing earned only modest attention.
But at the Heart Rhythm Society (HRS) 2022 scientific sessions in San Francisco, cardiac pacing consolidated its comeback and entered the super-cool category.
Not one but three late-breaking clinical trials considered the role of pacing the heart's conduction system for both preventive and therapeutic purposes. Conduction system pacing, or CSP as we call it, includes pacing the His bundle or the left bundle branch. Left bundle-branch pacing has now largely replaced His-bundle pacing.
Before I tell you about the studies, let's review why CSP disrupts the status quo.
The core idea goes back to basic physiology: After the impulse leaves the atrioventricular node, the heart's specialized conduction system allows rapid and synchronous conduction to both the right and left ventricles.
Standard cardiac pacing means fixing a pacing lead into the muscle of the right ventricle. From that spot, conduction spreads via slower muscle-to-muscle conduction, which leads to a wide QRS complex and the right ventricle contracts before the left ventricle.
While such dyssynchronous contraction is better than no contraction, this approach leads to a
