Low lead one ratio predicts clinical outcomes in left bundle branch block
Zak Loring1,2, Brett D Atwater1,2, Xiaojuan Xia2,3
1Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, North Carolina.
Insights
The novel Lead One Ratio (LOR) electrocardiogram (ECG) marker effectively predicts reduced left ventricular ejection fraction (LVEF) and poorer outcomes in patients with left bundle branch block (LBBB). This ECG finding is crucial for assessing cardiac function and prognosis.
Area of Science:
- Cardiology
- Medical Imaging
- Electrocardiography
Background:
- Left bundle branch block (LBBB) is associated with impaired left ventricular (LV) systolic function and adverse clinical outcomes.
- Accurate assessment of LV function and myocardial scar is critical for guiding management in LBBB patients.
- Novel electrocardiographic (ECG) markers may offer non-invasive methods for evaluating cardiac status in LBBB.
Purpose of the Study:
- To evaluate the association of a novel ECG marker, the Lead One Ratio (LOR), with left ventricular ejection fraction (LVEF), myocardial scar, and clinical outcomes in patients with LBBB.
Main Methods:
- A derivation cohort (n=240) was used to determine optimal LOR thresholds for predicting myocardial scar and LVEF < 35%.
- An independent validation cohort (n=196) tested the association of LOR with scar, LVEF, and major adverse cardiac events (death, heart transplant, LVAD implantation).
- Statistical analyses included receiver operator characteristic curves, logistic regression, and Cox proportional hazards models.
Main Results:
- An LOR threshold < 12.1 was associated with lower LVEF (30% vs. 40%) and predicted LVEF < 35% in validation cohorts.
- LOR < 12.1 predicted adverse outcomes (death, transplant, LVAD) with an adjusted hazard ratio of 1.53.
- LOR < 13.7 was not consistently associated with myocardial scar presence or size.
Conclusions:
- The ECG Lead One Ratio (LOR) < 12.1 is a valuable, non-invasive predictor of reduced left ventricular systolic function in LBBB patients.
- LOR < 12.1 is associated with a poorer prognosis, including an increased risk of major adverse cardiac events.
- This novel ECG marker holds potential for improving risk stratification and guiding therapeutic decisions in LBBB management.
Introduction:
We evaluated the association between a novel electrocardiographic (ECG) marker of late, rightward electrocardiographic forces (termed the lead one ratio [LOR]), and left ventricular ejection fraction (LVEF), myocardial scar, and clinical outcomes in patients with left bundle branch block (LBBB).
Methods And Results:
LOR was calculated in patients with LBBB from a derivation cohort (n = 240) and receiver operator characteristic curves identified optimal threshold values for predicting myocardial scar and LVEF less than 35%. An independent validation cohort of patients with LBBB (n = 196) was used to test the association of LOR with the myocardial scar, LVEF, and the likelihood of death, heart transplant or left ventricular assist device (LVAD) implantation. The optimal thresholds in the derivation cohort were LOR less than 13.7 for identification of scar (sensitivity 55%, specificity 80%), and LOR less than 12.1 for LVEF less than 35% (sensitivity 49%, specificity 80%). In the validation cohort, LOR less than 13.7 was not associated with scar size or presence (P > 0.05 for both). LOR less than 12.1 was associated with lower LVEF (30 [20-40] versus 40 [25-55]%; P = 0.002) and predicted LVEF less than 35% in univariable (odds ratio [OR], 2.2 [1.2-4.1]; P = 0.01) and multivariable analysis (OR, 2.2 [1.2-4.3]; P = 0.02). LOR less than 12.1 was associated with scar presence when patients with nonischemic cardiomyopathy were excluded (OR = 7.2 [1.5-33.2]; P = 0.002). LOR less than 12.1 had an adjusted hazard ratio of 1.53 ([1.05-2.21]; P = 0.03) for death, transplant or LVAD implantation.
Conclusions:
In conclusion, ECG LOR less than 12.1 predicts reduced-LV systolic function and poorer prognosis in patients with LBBB.
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