Importance: Recent studies have questioned the presumed low-risk status of patients with asymptomatic nonsevere aortic stenosis (AS). Whether annual N-terminal pro-brain natriuretic peptide (NT-proBNP) measurements are useful for risk assessment is unknown.
Objective: To assess the association of annual NT-proBNP measurements with clinical outcomes in patients with nonsevere AS.
Design, Setting, and Participants: Analysis of annual NT-proBNP concentrations in the multicenter, double-blind Simvastatin and Ezetimibe in Aortic Stenosis (SEAS) randomized clinical trial was performed. SEAS was conducted from January 6, 2003, to April 1, 2008. Blood samples were analyzed in 2016, and data analysis was performed from February 10 to October 10, 2021. SEAS included 1873 patients with asymptomatic AS not requiring statin therapy with transaortic maximal flow velocity from 2.5 to 4.0 m/s and preserved ejection fraction. This substudy included 1644 patients (87.8%) with available blood samples at baseline and year 1.
Exposures: Increased age- and sex-adjusted NT-proBNP concentrations at year 1 and a 1.5-fold or greater relative NT-proBNP concentration change from baseline to year 1. Moderate AS was defined as baseline maximal flow velocity greater than or equal to 3.0 m/s.
Main Outcomes and Measures: Aortic valve events (AVEs), which are a composite of aortic valve replacement, cardiovascular death, or incident heart failure due to AS progression, were noted. Landmark analyses from year 1 examined the association of NT-proBNP concentrations with outcomes.
Results: Among 1644 patients, 996 were men (60.6%); mean (SD) age was 67.5 (9.7) years. Adjusted NT-proBNP concentrations were within the reference range (normal) in 1228 of 1594 patients (77.0%) with NT-proBNP values available at baseline and in 1164 of 1644 patients (70.8%) at year 1. During the next 2 years of follow-up, the AVE rates per 100 patient-years for normal vs increased adjusted NT-proBNP levels at year 1 were 1.39 (95% CI, 0.86-2.23) vs 7.05 (95% CI, 4.60-10.81) for patients with mild AS (P < .01), and 10.38 (95% CI, 8.56-12.59) vs 26.20 (95% CI, 22.03-31.15) for those with moderate AS (P < .01). Corresponding all-cause mortality rates were 1.05 (95% CI, 0.61-1.81) vs 4.17 (95% CI, 2.42-7.19) for patients with mild AS (P < .01), and 1.60 (95% CI, 0.99-2.57) vs 4.78 (95% CI, 3.32-6.87) for those with moderate AS (P < .01). In multivariable Cox proportional hazards regression models, the combination of a 1-year increased adjusted NT-proBNP level and 1.5-fold or greater NT-proBNP level change from baseline was associated with the highest AVE rates in both patients with mild AS (hazard ratio, 8.12; 95% CI, 3.53-18.66; P < .001) and those with moderate AS (hazard ratio, 4.05; 95% CI, 2.84-5.77; P < .001).
Conclusions and Relevance: The findings of this study suggest that normal NT-proBNP concentrations at 1-year follow-up are associated with low AVE and all-cause mortality rates in patients with asymptomatic nonsevere AS. Conversely, an increased 1-year NT-proBNP level combined with a 50% or greater increase from baseline may be associated with high AVE rates.
Trial Registration: ClinicalTrials.gov Identifier: NCT00092677.