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J Cardiovasc Electrophysiol. 2019 May;30(5):709-716. doi: 10.1111/jce.13875. Epub 2019 Feb 19.

Low lead one ratio predicts clinical outcomes in left bundle branch block.

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Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, North Carolina.
Department of Health Services, University of Washington, Seattle, Washington.
Cardiology Department, Heart Research Follow-Up Program, University of Rochester, New York.
Department of Clinical Physiology, Karolinska Institute, and Karolinska University Hospital, Stockholm, Sweden.
Department of Cardiology, VU University Medical Center, Amsterdam, The Netherlands.
Division of Cardiology, Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
Division of Applied Regulatory Science, Office of Clinical Pharmacology, Office of Translational Science, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland.



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).


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.


In conclusion, ECG LOR less than 12.1 predicts reduced-LV systolic function and poorer prognosis in patients with LBBB.


clinical outcomes; electrocardiography; left bundle branch block; magnetic resonance imaging; myocardial scar


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