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Inconsistent echocardiographic grading of aortic stenosis: is the left ventricular outflow tract important?
Hector I Michelena1, Edit Margaryan, Fletcher A Miller
1Division of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA. michelena.hector@mayo.edu
Insights
Left ventricular outflow tract diameter (LVOTd) significantly impacts aortic stenosis (AS) severity assessment. Current guidelines show inconsistencies, particularly for smaller LVOTd, suggesting a need for revised aortic valve area (AVA) thresholds.
Area of Science:
- Cardiology
- Echocardiography
- Medical Imaging
Background:
- Echocardiographic assessment of aortic stenosis (AS) severity relies on guidelines that may lead to discrepancies.
- The left ventricular outflow tract diameter (LVOTd) is a potential factor contributing to these inconsistencies.
Purpose of the Study:
- To investigate the role of LVOTd in echocardiographic severity grading of aortic stenosis (AS).
- To explore alternative thresholds for improving the consistency of AS assessment.
Main Methods:
- Retrospective analysis of echocardiographic data from 2000-2010.
- Patients with preserved ejection fraction (EF ≥50%) and specific AS criteria were categorized by LVOTd (small, average, large).
- Inconsistency in AS severity classification was assessed, and alternative aortic valve area (AVA) thresholds were explored.
Main Results:
- Significant differences in patient demographics and hemodynamics were observed across LVOTd groups.
- Despite similar mean gradients and peak velocities, mean AVA varied significantly by LVOTd, leading to different AS severity classifications.
- Lower AVA cut-offs (0.8-0.9 cm²) reduced inconsistencies in AS severity grading for small and average LVOTd groups.
Conclusions:
- LVOTd is a significant factor in the inconsistent echocardiographic assessment of AS severity.
- Current guideline definitions are most consistent for large LVOTd; lower AVA thresholds warrant investigation for average and small LVOTd.
- The dimensionless index (DI) for severe AS is highly variable with LVOTd, necessitating guideline revision.
Objective:
Discrepancy in the echocardiographic severity grading of aortic stenosis (AS) based on current guidelines has been reported. We sought to investigate the left ventricular outflow tract diameter (LVOTd) as a source of inconsistencies, and to explore hypothetical alternatives for discrepancy improvement.
Design:
Retrospective echocardiographic cross-sectional analysis.
Setting:
From 2000 to 2010, we identified all AS patients with left ventricular EF ≥50%, mean gradient (MG) ≥20 mm Hg, aortic valve area (AVA) ≤2.5 cm(2),
Results:
Of 9488 total patients, 58% were men, LVOTd 2.18±0.19 cm, peak velocity (Vmax) 3.9±0.8 m/s, MG 37±16 mm Hg, and AVA 1.09±0.34 cm(2). Small LVOTd patients were older women (91%) with worse systemic haemodynamics and more prevalent paradoxical low-flow, compared with average and large LVOTd patients (all parameters p <0.001). Despite clinically similar MG and Vmax across all groups, mean AVA ranged from 0.88 to 1.25 cm(2) (p <0.001), classifying small LVOTd patients as severe, average LVOTd as moderate-severe and large LVOTd as moderate. For patients with large, average and small LVOTd, an AVA of 1 cm(2) corresponded to MG of 42, 35 and 29 mm Hg, Vmax of 4.1, 3.8 and 3.5 m/s and dimensionless index (DI) of 0.22, 0.29 and 0.36, respectively. An AVA cut-off of 0.8 cm(2) reduced severe AS inconsistency from 48% to 26% for small LVOTd patients. An AVA cut-off of 0.9 cm(2) reduced severe AS inconsistency from 37% to 26% for average LVOTd patients. The current AVA cut-off of 1 cm(2) was consistent for large LVOTd patients.
Conclusions:
The LVOTd is associated with significant inconsistencies in AS assessment by current guidelines. For patients with normal EF and normal flow, current guideline definition of severe AS is most consistent for patients with large LVOTd, but not so for patients with average or small LVOTd in whom lower AVA cut-offs should be further studied. The DI cut-off for severe AS is highly variable depending on the LVOTd and guideline revision of this threshold should be considered.
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