At what flow rate does the aortic valve gradient become severely elevated? Implications for guideline recommendations on aortic valve area cutoffs
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Department of Medicine, Cardiology Division, Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, New York, USA
Department of Cardiology, Westchester Medical Center and the Department of Medicine, New York Medical College, Valhalla, New York, USA
Submission date: 2019-12-03
Final revision date: 2020-02-26
Acceptance date: 2020-03-12
Online publication date: 2021-03-21
Corresponding author
Wilbert S. Aronow   

New York Medical College
Aortic stenosis (AS) is considered severe when the aortic valve area (AVA) is < 1.0 cm2 and the mean aortic valve gradient (mAVG) exceeds 40 mm Hg. Since many patients with AVA < 1.0 cm2 do not manifest an mAVG > 40 mm Hg, we sought to determine the AVA at which mAVG tends to exceed 40 mm Hg in a sample of subjects with varied transvalvular flow rates.

Material and methods:
Our echocardiography database was queried for subjects with native valve AS. We selected 200 subjects with an AVA < 1.0 cm2. The sample was selected to include subjects with varied mean systolic flow (MSF) rates. Linear regression was performed to determine the relationship between MSF and mAVG. Since this relationship varied by AVA, the regression was stratified by AVA (critical < 0.6 cm2, severe 0.6–0.79 cm2, moderately severe 0.8–0.99 cm2).

The study sample was 79 ±12 years old and was 60% female. The MSF rate at which mAVG tended to exceed 40 mm Hg was 120 ml/s for critical AVA, 183 ml/s for severe AVA and 257 ml/s for moderately severe AVA. Those with moderately severe AVA rarely (8%) had an mAVG > 40 mm Hg at a wide range of MSF. In contrast, those with severe AVA typically (75%) had mAVG > 40 mm Hg when MSF was normal (> 200 ml/s). Those with critical AVA frequently (44%) had mAVG > 40 mm Hg, even when MSF was reduced.

Subjects with AVA of 0.8 and 0.9 cm2 rarely had mAVG > 40 mm Hg, even when the transvalvular flow rate was normal. Using current guidelines, it is not clear if such cases should be classified as severe.

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