Abstract
Cardiac resynchronization therapy (CRT) has become part of the standard of care for symptomatic patients with heart failure, reduced ejection fraction (HRrEF), and wide QRS, despite optimal medical therapy. Device technology, operator experience, and post-implant optimization on follow-up have significantly improved CRT response during the last decade. In parallel, conduction system pacing (CSP) has emerged as a new and potentially better tool for maintaining physiological ventricular activation in patients with antibradycardia pacing, as well as an alternative for dyssynchrony correction in HFrEF patients. The current review focuses on cardiac dyssynchrony pathophysiology and correction methods, clinical evidence on CRT and CSP as therapies for cardiac dyssynchrony, and the role of each according to clinical evidence and current guidelines for HFrEF treatment.