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

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

Methods: In this retrospective cohort study, 930 patients who underwent transcatheter aortic valve replacement for severe symptomatic AS at Mayo Clinic sites from 2012-2017 were included. 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 tomographic characteristics, including aortic valve area, aortic valve calcium score, left ventricular ejection fraction, and the prevalence of tricuspid regurgitation, and atrial fibrillation were analyzed. One- and 5-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 patients with NFLG AS were reclassified into the LFLG group. Patients with LFLG AS had the highest prevalence of atrial fibrillation or flutter (60%) and tricuspid regurgitation (17%). Aortic valve calcium score was significantly lower in the NFLG group compared with the HG and LFLG groups. One-year mortality was highest in the LFLG group (17.4%), followed by the HG (13.9%) and NFLG (10.9%) groups, but the difference was not statistically significant (P = .20). The 5-year mortality rate was higher in the LFLG group (55.6%) compared with the NFLG (47.2%) and HG (47.9%) groups but did not reach statistical significance (P = .20).

Conclusions: LFLG AS was associated with more comorbidities and higher mortality compared with HG and NFLG AS, 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.