Lead one ratio: A new electrocardiogram marker for cardiac resynchronization therapy response

BACKGROUND: Wider QRS duration and presence of left bundle branch block (LBBB) predict better cardiac resynchronization therapy (CRT) response. Despite strict patient selection, one-third of patients have a sub-optimal response. We aim to evaluate the impact of lead one ratio (LOR) on CRT response.METHODS: We enrolled ۹۳ patients receiving CRT from August ۲۰۱۶ to August ۲۰۱۹. Pre-implant ۱۲-lead electrocardiogram (ECG) was recorded, and LOR was derived by dividing the maximum positive deflection of QRS complex in ECG lead I by the maximum negative deflection in lead I; cut-off value of ۱۲ was used to divide the cohort into two groups. Patients were followed for ۶ months, and outcomes were compared for CRT response, New York Heart Association (NYHA) class improvement, all-cause mortality, and heart failure (HF) hospitalization events.RESULTS: At the end of ۶-month follow-up, LOR ≥ ۱۲ was associated with significantly better CRT response (۷۵.۷۶% vs. ۵۱.۸۵% in LOR < ۱۲, P = ۰.۰۲), lower mortality per ۱۰۰ patient-years (۹.۰۹ vs. ۱۴.۸۱ in LOR < ۱۲, P = ۰.۰۱۲), and more improvement in HF symptoms (NYHA improvement) (۷۸.۷۹% vs. ۵۵.۵۶% in LOR < ۱۲, P = ۰.۰۲). Patients with LOR < ۱۲ had more HF hospitalization events (۲.۰۴ vs. ۱.۸۱ episodes in LOR ≥ ۱۲, P = ۰.۰۲۹) and less QRS narrowing (∆۵.۷۴ ± ۲.۰۹ vs. ∆۷.۱۰ ± ۳.۹۷ ms in LOR ≥ ۱۲, P = ۰.۰۱). QRS duration and LBBB morphology were predictors of response in both groups of patients.CONCLUSION: LOR ≥ ۱۲ was associated with better response to CRT, less HF hospitalization, and more relief in HF symptoms. This ratio helps to identify possible sub-optimal response among patients with an indication for CRT.

Keywords:

Electrocardiography , Left Bundle Branch Block , Cardiac Resynchronization Therapy , Heart Failure