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Comparison of the Right Atrial Expansion Index with Inferior Vena Cava Assessment for Echocardiographic Estimation of
Davide Genovese1, Marco Previtero2, Giacomo Prete2
1Cardiology Unit, Department of Cardiac-Thoracic-Vascular Sciences and Public Health, University of Padova, Padova, Italy; Cardiology Unit, Cardio-Neuro-Vascular Department, Ca' Foncello Hospital, Treviso, Italy.
Insights
The natural log of the right atrial expansion index (lnRAEI) is a more accurate noninvasive method for estimating right atrial pressure (RAP) than inferior vena cava (IVC) assessment. This finding holds significant implications for managing cardiac diseases noninvasively.
Area of Science:
- Cardiology
- Medical Imaging
- Hemodynamics
Background:
- Right atrial pressure (RAP) evaluation is crucial for cardiac disease management.
- Right heart catheterization (RHC) directly measures RAP but is invasive.
- Transthoracic echocardiography (TTE) offers noninvasive RAP estimation via inferior vena cava (IVC) assessment, albeit with limitations.
Purpose of the Study:
- To validate the right atrial expansion index (RAEI) as a noninvasive parameter for estimating RAP.
- To compare the accuracy of RAEI with existing noninvasive methods like IVC assessment.
Main Methods:
- Retrospective enrollment of 1,020 patients with chronic cardiac diseases undergoing RHC and TTE within 24 hours.
- Offline measurement of RAEI and other TTE parameters, blinded to RHC results.
- Statistical analysis to correlate RAEI with RHC-measured RAP and compare predictive accuracy.
Main Results:
- The natural log of RAEI (lnRAEI) demonstrated a significant logarithmic correlation with RAP (r = -0.65, P < .001).
- lnRAEI outperformed IVC assessment in identifying elevated RAP (≥10 mm Hg) in both derivation (AUC 0.840) and validation (AUC 0.826) cohorts.
- A derived equation using lnRAEI provided more accurate RAP estimation than IVC assessment in the validation cohort.
Conclusions:
- The natural log of RAEI is a more accurate noninvasive parameter for estimating RAP compared to IVC assessment.
- RAEI offers a valuable, noninvasive tool for assessing right atrial compliance and RAP in patients with cardiac diseases.
Background:
Evaluating right atrial pressure (RAP) is essential for managing cardiac diseases. Right heart catheterization (RHC) measures RAP directly but is invasive. In contrast, transthoracic echocardiography (TTE) provides a noninvasive estimate of RAP through inferior vena cava (IVC) assessment despite some limitations. The right atrial expansion index (RAEI) reflects right atrial compliance by measuring the relative increase in volume during the reservoir phase. This study aimed to validate RAEI as a noninvasive parameter for estimating RAP.
Methods:
We retrospectively enrolled 1,020 patients (728 in the derivation and 292 in the validation cohort) with various chronic cardiac diseases who underwent clinically indicated RHC and TTE within 24 hours. Right atrial pressure was measured during the RHC and defined as elevated when above 10 mm Hg. Right atrial expansion index and other TTE parameters were measured offline and blinded to RHC results.
Results:
In the derivation cohort, RAEI showed a logarithmic correlation with RAP (lnRAEI-RAP: r = -0.65, P < .001). The natural log of RAEI was an independent and additive predictor of RAP, outperforming clinical, hemodynamic, and echocardiographic parameters, including IVC assessment. The natural log of RAEI was more accurate than IVC assessment for identifying RAP ≥10 mm Hg (area under the curve lnRAEI, 0.840,;P < .001; optimal cutoff, lnRAEI <3.53); this finding was replicated in the validation cohort (area under the curve lnRAEI, 0.826; P < .001). Furthermore, lnRAEI <3.53 was confirmed as an optimal cutoff for identifying RAP ≥10 mm Hg in the validation cohort as well (sensitivity, 74%; specificity, 79%; accuracy, 78%). Finally, the equation RAP = 19.3 - (3.29 × lnRAEI) derived from the derivation cohort estimated RAP more accurately (-0.2 ± 3.1 mm Hg) than IVC assessment (1.5 ± 4.2 mm Hg) in the validation cohort.
Conclusions:
In this patient cohort, lnRAEI was more accurate than IVC assessment for noninvasive RAP estimation.
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