Physiologic Pacing in 2025: Guidance Made Simple

Conventional right ventricular pacing (RVP), particularly at the right ventricular apex, has long been the standard approach for ventricular pacing in patients requiring permanent pacemakers. However, RVP has been shown to introduce electrical and mechanical dyssynchrony, resulting in adverse remodelling, atrial fibrillation, and heart failure. The deleterious effects of a high RVP burden have been demonstrated in the MOST and DAVID trials, wherein patients with ventricular pacing >40% were identified as being at risk of increased adverse clinical outcomes, such as hospitalization for heart failure and death (hazard ratio [HR] 1.61; 95% confidence interval [CI] 1.06–2.44). In patients with baseline ventricular systolic dysfunction and left bundle branch block or a high ventricular pacing burden, cardiac resynchronization therapy (CRT) using conventional biventricular pacing (BiVP) has been shown to be superior to RVP in preventing ventricular dilation, hospitalization for heart failure, and death. Both the BLOCK-HF trial, which compared BiVP to RV pacing in patients with a left ventricular ejection fraction (LVEF) ≤50% and a high pacing burden, and the MADIT-CRT trial, which compared implantable cardioverter-defibrillator therapy alone to CRT with defibrillator in patients with LVEF ≤30% and QRS duration ≥130ms, showed a reduction in all-cause mortality and heart failure events in the BiVP group (HR 0.74; 95% CI 0.60–0.90 and HR 0.66; 95% CI 0.52–0.84, respectively). However, approximately one-third of patients do not respond to conventional BiVP. Moreover, the benefits of conventional BiVP have not been consistently shown across all cohorts. To overcome the detrimental effects of RVP and the limitations of conventional BiVP, conduction system pacing (CSP) was introduced. This approach harnesses the His-Purkinje system, thereby delivering stimulation mimicking native ventricular activation. The two primary CSP techniques, His bundle pacing (HBP) and left bundle branch area pacing (LBBAP), have demonstrated promise in improving both electrical synchrony and clinical outcomes.