Conduction System Pacing vs Biventricular Pacing in Heart Failure and Wide QRS Patients

Conduction system pacing (CSP) has emerged as an alternative to biventricular pacing (BiVP). Randomized studies comparing both therapies are scarce and do not include left bundle branch pacing. This study aims to compare ventricular resynchronization achieved by CSP vs BiVP in patients with cardiac resynchronization therapy indication. LEVEL-AT (Left Ventricular Activation Time Shortening with Conduction System Pacing vs Biventricular Resynchronization Therapy) was a randomized, parallel, controlled, noninferiority trial. Seventy patients with cardiac resynchronization therapy indication were randomized 1:1 to BiVP or CSP, and followed up for 6 months. Crossover was allowed when primary allocation procedure failed. Primary endpoint was the change in left ventricular activation time, measured using electrocardiographic imaging. Secondary endpoints were left ventricular reverse remodeling and the combined endpoint of heart failure hospitalization or death at 6-month follow-up. Thirty-five patients were allocated to each group. Eight (23%) patients crossed over from CSP to BiVP; 2 patients (6%) crossed over from BiVP to CSP. Electrocardiographic imaging could not be performed in 2 patients in each group. A similar decrease in left ventricular activation time was achieved by CSP and BiVP (−28 ± 26 ms vs −21 ± 20 ms, respectively; mean difference −6.8 ms; 95% CI: –18.3 ms to 4.6 ms; P < 0.001 for noninferiority). Both groups showed a similar change in left ventricular end-systolic volume (−37 ± 59 mL CSP vs −30 ± 41 mL BiVP; mean difference: −8 mL; 95% CI: −33 mL to 17 mL; P = 0.04 for noninferiority) and similar rates of mortality or heart failure hospitalizations (2.9% vs 11.4%, respectively) (P = 0.002 for noninferiority). Similar degrees of cardiac resynchronization, ventricular reverse remodeling, and clinical outcomes were attained by CSP as compared to BiVP. CSP could be a feasible alternative to BiVP. (LEVEL-AT [Left Ventricular Activation Time Shortening With Conduction System Pacing vs Biventricular Resynchronization Therapy]; NCT04054895)