Reevaluating Normal-Flow Low-Gradient Severe Aortic Stenosis: Clinical Phenotypes and Outcomes in Severe Aortic Stenosis Among TAVR Patients.

Background: Aortic stenosis (AS) is a complex condition with various hemodynamic subtypes, each with distinct clinical profiles and outcomes. This study aimed to assess the characteristics and outcomes of different AS phenotypes based on flow and gradient patterns.

Methods: In this retrospective cohort study, we included 930 patients who underwent transcatheter aortic valve replacement (TAVR) for severe symptomatic AS at Mayo Clinic sites from 2012-2017. Patients were classified into three groups: high gradient (HG), low-flow low-gradient (LFLG), and normal-flow low-gradient (NFLG). Baseline clinical, echocardiographic, and computed tomography (CT) characteristics, including aortic valve area (AVA), aortic valve calcium score (AVCS), left ventricular ejection fraction (LVEF), and the prevalence of tricuspid regurgitation (TR) and atrial fibrillation were analyzed. One- and five-year all-cause mortality outcomes were compared using Kaplan-Meier analysis and Cox proportional hazards models.

Results: The final cohort included 273 patients in the NFLG group (29.4%), 563 in the HG group (60.5%), and 94 in the LFLG group (10.1%). After reevaluation and careful review of the echocardiograms, 41 NFLG patients were reclassified into the LFLG group. LFLG patients had the highest prevalence of atrial fibrillation/flutter (60%) and TR (17%). AVCS was significantly lower in NFLG compared to HG and LFLG groups. One-year mortality was highest in the LFLG group (17.4%), followed by HG (13.9%) and NFLG (10.9%), but the difference was not statistically significant (p=0.2). Five-year mortality rate was higher in the LFLG group (55.6%) compared to NFLG (47.2%) and HG (47.9%) but did not reach statistical significance (p=0.2).

Conclusions: LFLG AS is associated with more comorbidities and higher mortality compared to HG and NFLG groups, though differences in mortality were not statistically significant. The NFLG group, after close review and reclassification, showed the least significant AS. Randomized trials are needed to clarify the prognosis and management of NFLG AS.