Is flow better in mL/m2 or mL/s - a practical reflection on aortic stenosis

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Severe aortic stenosis is characterized for a high mean gradient (>40mmHg) and an aortic valve area (AVA ≤1cm2). There is a population of patients with discordant findings. These patients present with a lower mean gradient (<40mmHg) and area (AVA ≤1cm2). This states are explained by a low flow (indexed SV ≤35ml/m2). Some studies demonstrated that a flow rate (determined by dividing SV by ejection time) inferior to 200 mL/s is also associated with poor prognosis. Can this be an alternative in stratifying patients with an AVA ≤1cm2? Purpose This paper aims to compare flow assessment by the conventional way with flow calculated in ml/s in patients with AVA ≤1cm2 Methods We present a retrospective study from all consecutive patients to whom an echocardiogram was performed in our hospital during the years 2017 and 2018 which meet the criteria for low gradient aortic stenosis. Comorbidities were analysed for each subgroup as well as echocardiographic variables to properly characterize aortic stenosis. Results A total of 118 patients met the criteria for severe aortic stenosis with a valvular area ≤1cm2. This population was made up of 18 patients with severe aortic stenosis low flow, low gradient with depressed ejection fraction and 32 patients with preserved ejection fraction. The other 68 patients represented patients with a normal flow, low gradient aortic stenosis. There is a strong correlation between the variable SVi and Flow Rate (r = 0,796, p < 0,001). A linear regression shows that the flow rate equivalent to a SVi of 35mL/m2 in our sample is 203mL/s, near the value of other studies. 10 (31.3%) patients with severe aortic stenosis low flow, low gradient with preserved ejection fraction, 3 (16.7%) patients with severe aortic stenosis low flow, low gradient with depressed ejection fraction and 53 (77.9%) patients with normal flow, low gradient aortic stenosis would have a flow superior to 200mL/s. Conclusion The use of flow rate systematically would downgrade the severity of valvular lesions with possible need for intervention. However, in certain dubious cases its application may identify a subpopulation with need for further study and probable treatment, such as the patients with normal flow, low gradient aortic stenosis. Further studies of this subgroup of patients are warranted to reach any final conclusions. Abstract Figure.