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Lead one ratio: A new electrocardiogram marker for cardiac resynchronization therapy response
Ajay Raj1, Ranjit Kumar Nath1, Bhagya Narayan Pandit1
1Department of Cardiology, Atal Bihari Vajpayee Institute of Medical Sciences AND Dr. Ram Manohar Lohia Hospital, New Delhi, India.
Insights
A higher Lead One Ratio (LOR) predicts better cardiac resynchronization therapy (CRT) response and reduced heart failure hospitalizations. This simple ECG measurement can identify patients likely to benefit from CRT.
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.
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 93 patients receiving CRT from August 2016 to August 2019. Pre-implant 12-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 12 was used to divide the cohort into two groups. Patients were followed for 6 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 6-month follow-up, LOR ≥ 12 was associated with significantly better CRT response (75.76% vs. 51.85% in LOR < 12, P = 0.02), lower mortality per 100 patient-years (9.09 vs. 14.81 in LOR < 12, P = 0.012), and more improvement in HF symptoms (NYHA improvement) (78.79% vs. 55.56% in LOR < 12, P = 0.02). Patients with LOR < 12 had more HF hospitalization events (2.04 vs. 1.81 episodes in LOR ≥ 12, P = 0.029) and less QRS narrowing (∆5.74 ± 2.09 vs. ∆7.10 ± 3.97 ms in LOR ≥ 12, P = 0.01). QRS duration and LBBB morphology were predictors of response in both groups of patients.
Conclusion:
LOR ≥ 12 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.
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