Outcome of Normal-Flow Low-Gradient Severe Aortic Stenosis With Preserved Left Ventricular Ejection Fraction: A Propensity-Matched Study

Background-Normal-flow, low-gradient severe aortic stenosis (NF-LG-SAS), defined by aortic valve area <1 cm(2), mean gradient <40 mm Hg, and indexed stroke volume >35 mL/m(2), is the most prevalent form of low-gradient aortic stenosis (AS). However, the true severity of AS and the management of NF-LG-SAS are controversial. The aim of this study was to evaluate the outcome of patients with NF-LG-SAS compared with moderate AS (MAS) and with high-gradient severe-AS (HG-SAS). Methods and Results-A total of 154 patients with NF-LG-SAS, 366 with MAS (aortic valve area between 1.0 and 1.3 cm(2)), and 1055 with HG-SAS were included. On multivariate analysis, after adjustment for covariates of prognostic importance, NF-LG-SAS patients did not exhibit an excess risk of mortality compared with MAS patients under medical management (hazard ratio=1.13 [95% CI, 0.82-1.56]; P=0.45) and under medical and surgical management (hazard ratio 1.06 [95% CI, 0.79-1.43]; P=0.70), even after further adjustment for aortic valve replacement (hazard ratio=1.09 [95% CI, 0.81-1.48]; P=0.56). The 6-year cumulative incidence of aortic valve replacement (performed in accordance with guidelines) was comparable between the 2 groups (39 +/- 4% for NF-LG-SAS and 35 +/- 3% for MAS, P=0.10). After propensity score matching (n=226), NF-LG-SAS and MAS patients also had comparable outcomes under medical (P=0.41) and under medical and surgical management (P=0.52). NF-LG-SAS had better outcomes than HG-SAS patients (adjusted hazard ratio 1.84 [95% CI, 1.18-2.88]; P<0.001). Conclusions-This study shows that patients with NF-LG-SAS have a comparable outcome to those with MAS when aortic valve replacement is performed during follow-up according to guidelines, mostly at the stage of HG-SAS. Rigorous echocardiographic assessment to rule out measurement errors and close follow-up are essential to detect progression to true severe AS in NF-LG-SAS.