Prognostic Value of Transvalvular Flow Rate in Aortic Stenosis: Implications for Risk Stratification

Background: Timing of treatment of aortic stenosis (AS) is of key importance. AS severity is currently determined by transthoracic echocardiography (TTE) with a main focus on mean trans-aortic gradients. However, echocardiography has its limitations. The transvalvular flow rate (Q), is defined as the ratio of stroke volume (SV) to ejection time (ET): Q = SV/ET. Purpose: To examine the prognostic value of aortic transvalvular flow rate (Q), in patients with moderate or severe AS. Methods: Clinical data from 824 patients diagnosed with AS between 2017 and 2020, and followed up until 2022 for four clinical outcomes: mortality, congestive heart failure (CHF), transcatheter aortic valve implantation (TAVI), and surgical aortic valve replacement (SAVR) was used for this retrospective study. Univariate and multivariate regression analyses were performed for the whole cohort and for the moderate AS subgroup, to identify prognostic markers. Kaplan-Meier survival analysis was conducted for different transvalvular flow rates and AS severities. Results: Findings demonstrate that lower Q is a significant risk factor for all-cause mortality even when adjusted for other echocardiographic and clinical variables. Survival analysis for the composite outcome occurrence (TAVI, SAVR, CHF, or mortality) and mortality showed significant differences between groups stratified by AS severity and Q (p value <0.0001). Specifically, Q was more substantial in the moderate AS group. Conclusion: Transvalvular flow rate (Q) is independently prognostic for all-cause mortality. Furthermore, patients with moderate AS and lower Q should be closely monitored. Flow rate assessment should be integrated into the diagnosis, classification, and prognosis framework for AS.