Outcome of normal-flow low-gradient “severe” aortic stenosis with preserved left ventricular ejection fraction: A propensity matched study

Abstract

Normal-flow low-gradient severe aortic stenosis (NF-LG-SAS), defined by aortic-valve area < 1cm 2 , mean gradient < 40 mmHg 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 is controversial. The aim of this study was to evaluate the outcome of patients with NF-LG-SAS compared to patients with moderate AS (MAS), who are considered to be suitable for conservative management. A total of 520 patients were included in this study: 154 with NF-LG-SAS and 366 with MAS (aortic-valve area between 1.0 and 1.3 cm 2 ). On Cox multivariate analysis, after adjustment for covariates of prognostic importance, NF-LG-SAS patients did not exhibit an excess risk of mortality compared to MAS patients, under medical management ( P = 0.45) and under medical and surgical management ( P = 0.70), even after further adjustment for aortic-valve replacement (AVR) ( P = 0.56). The 6-year cumulative incidence of AVR (performed in accordance with current guidelines) was comparable between the two groups (39 ± 4% for NF-LG-SAS and 35 ± 3% for MAS, P = 0.10). After propensity score matching (n = 226), NF-LG-SAS patients and MAS patients also had comparable outcomes under medical ( P = 0.41), and under medical and surgical management ( P = 0.52) ( Fig. 1 ). This study shows that NF-LG-SAS have a comparable outcome to that of MAS when AVR was performed during follow-up according to guidelines, mostly at the stage of high-gradient AS. Rigorous echocardiographic assessment to rule out measurement errors and close follow-up are essential in NF-LG-SAS to detect progression to true severe AS.