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

Area of Science:

• Cardiology
• Electrophysiology
• Medical Imaging

Background:

• Wider QRS duration and left bundle branch block (LBBB) indicate better cardiac resynchronization therapy (CRT) response.
• Despite patient selection, approximately one-third of patients exhibit sub-optimal CRT response.
• The impact of Lead One Ratio (LOR) on CRT response requires further evaluation.

Purpose of the Study:

• To assess the efficacy of the Lead One Ratio (LOR) in predicting CRT response.
• To determine if LOR can identify patients with sub-optimal CRT outcomes.
• To correlate LOR with clinical outcomes including mortality and heart failure hospitalizations.

Main Methods:

• Ninety-three patients undergoing CRT were enrolled between August 2016 and August 2019.
• Pre-implant ECGs were analyzed to calculate LOR, defined by QRS deflections in lead I (cut-off value of 12).
• Patients were followed for 6 months to compare CRT response, NYHA class, mortality, and heart failure hospitalizations between LOR groups.

Main Results:

• A LOR ≥ 12 was significantly associated with better CRT response (75.76% vs. 51.85%, P=0.02).
• Patients with LOR ≥ 12 experienced lower mortality (9.09 vs. 14.81 per 100 patient-years, P=0.012) and fewer heart failure hospitalizations (P=0.029).
• LOR ≥ 12 correlated with improved heart failure symptoms (NYHA class) (78.79% vs. 55.56%, P=0.02) and greater QRS narrowing.

Conclusions:

• A LOR ≥ 12 is a strong predictor of positive CRT response.
• This ECG-derived ratio aids in identifying patients who may have a sub-optimal response to CRT.
• LOR offers a valuable tool for optimizing patient selection for CRT.