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Methodological discordance between apical four-chamber and biplane Simpson's method for left ventricular ejection
Hasan Burak İşleyen1, Sevil Tugrul Yavuz2, Sercan Bulut3
1Department of Cardiology, Nişantaşı University Faculty of Medicine, Istanbul, Turkey. hasanburak.isleyen@nisantasi.edu.tr.
Insights
Discrepancies between apical four-chamber (A4C) and biplane Simpson measurements of left ventricular ejection fraction (LVEF) are infrequent overall but common near treatment thresholds. Left ventricular enlargement drives these differences, favoring biplane methods in such cases.
Area of Science:
- Cardiology
- Medical Imaging
- Echocardiography
Background:
- Left ventricular ejection fraction (LVEF) is crucial for heart failure diagnosis and treatment decisions.
- The variability between apical four-chamber (A4C) and biplane Simpson methods for LVEF measurement at critical clinical thresholds is not well understood.
Purpose of the Study:
- To quantify the discordance between A4C and biplane Simpson LVEF measurements.
- To identify predictors of discordance, particularly near clinically actionable thresholds for heart failure treatment.
Main Methods:
- Analysis of 1,022 echocardiographic studies from the MIMIC-IV-ECHO-Ext-LVVOLUMES-A4C-ROI resource.
- Paired A4C and biplane LVEF labels were derived from the same DICOM sequences.
- Discordance was assessed at heart failure with reduced ejection fraction (HFrEF) and implantable cardioverter-defibrillator (ICD) thresholds, using Bland-Altman analysis and multivariable logistic regression.
Main Results:
- Overall LVEF discordance was 4.7% at the HFrEF threshold (<40%) and 3.1% at the ICD threshold (<35%).
- In the borderline zone (A4C LVEF 35-45%), discordance increased significantly to 30.9%.
- Left ventricular end-diastolic volume was the sole independent predictor of discordance (OR 1.61 per SD, p=0.0001).
Conclusions:
- While LVEF discordance between A4C and biplane methods is generally low, it becomes frequent near therapeutic cut-offs.
- Left ventricular dilatation is the primary factor contributing to this discordance.
- Biplane LVEF quantification is recommended for enlarged ventricles or when LVEF is near treatment thresholds.
Background:
Left ventricular ejection fraction (LVEF) remains central to heart failure phenotyping and device-based decision-making, yet the degree to which apical four-chamber (A4C) and biplane Simpson measurements diverge at clinically actionable thresholds is not well defined.
Methods:
We analysed 1,022 unique algorithmically derived echocardiographic studies from 784 patients in the credentialed MIMIC-IV-ECHO-Ext-LVVOLUMES-A4C-ROI resource. Each study contained paired A4C and biplane volumetric labels derived from the same annotated DICOM sequence. Discordance was defined primarily at the HFrEF threshold (LVEF < 40%). Agreement was assessed with Bland-Altman analysis, and independent predictors were evaluated using multivariable logistic regression with cluster-robust standard errors.
Results:
LVEF discordance at the HFrEF threshold occurred in 48 of 1,022 studies (4.7%, 95% CI 3.5-6.2%). At the ICD threshold (LVEF < 35%), discordance was present in 32 studies (3.1%). In the prespecified borderline zone (A4C LVEF 35-45%; n = 81), discordance rose to 30.9% (95% CI 21.9-41.6%). Mean bias was 0.11%, but the 95% limits of agreement were wide (- 13.5% to + 13.7%). LV end-diastolic volume was the only independent predictor of discordance (OR 1.61 per SD, 95% CI 1.27-2.05; p = 0.0001), and this association persisted after adjustment for acquisition variables.
Conclusions:
Discordance between A4C and biplane Simpson LVEF is uncommon across an unselected cohort but becomes frequent near therapeutic cut-offs. LV dilatation is the dominant driver. These findings support continued preference for biplane quantification when the ventricle is enlarged or the measured LVEF falls near a treatment threshold.
