Determinants and prognostic value of B-type natriuretic peptide in patients with aortic valve stenosis

Background: The prognostic value of N-terminal fragment of pro B-type natriuretic peptide (Nt-proBNP) in aortic stenosis (AS) is still being debated. We sought to evaluate the determinants of Nt-proBNP in AS and its prognostic value in asymptomatic patients.

Methods: Patients with pure isolated at least mild degenerative AS enrolled in our prospective cohort (2006-2013) constituted our population. Clinical and biological measurements as well as echocardiographic evaluations were performed at study entry for all patients. Severe AS was defined by a valve area <1cm². Asymptomatic patients were contacted every six months and seen every year. The occurrence of AS-related events (sudden death, congestive heart failure or new onset of symptoms) within two years was recorded prospectively.

Results: We enrolled 809 patients. Nt-proBNP increased with AS severity (p<0.0001) and symptomatic status (p<0.0001) but there was a wide overlap between groups of AS severity or symptomatic status. Nt-proBNP was the result of complex interactions between multiple determinants, including AS severity and symptomatic status but also age (p=0.0008), history of coronary artery disease (p=0.03), rhythm (p=0.007) and diastolic function (p<0.0001). Consequently, in asymptomatic patients with moderate/severe AS, normal ejection fraction and in sinus rhythm, Nt-proBNP was associated with AS-related events in univariate analysis (p=0.009) but not after adjustment for AS severity (p=0.12). Repeated Nt-proBNP measurements at one year did not improve their predictive value (p=0.43).

Conclusion: This study highlights the limitations of Nt-proBNP in AS and raises caution regarding its use, at least as a single factor, in the decision-making process regarding asymptomatic patients with AS.