Prognostic value of plasma B-type natriuretic peptide levels after exercise in patients with severe asymptomatic aortic stenosis

Background Exercise-stress echocardiography is useful in management and risk stratification of patients with asymptomatic aortic stenosis (AS). Resting B-type natriuretic peptide (BNP) level is associated with increased risk of adverse events. The incremental prognostic value of BNP response during exercise is unknown. Objective The purpose of this study was to assess the usefulness of plasma level of BNP during exercise to predict occurrence of events in asymptomatic patients with severe AS. Methods Resting and exercise-stress echocardiographic data and plasma BNP levels were prospectively collected in 211 asymptomatic AS patients in whom 157 had severe AS with preserved LVEF in two centres. The study end-point was the occurrence of death or aortic valve replacement. Results Plasma BNP level increased from rest to exercise (p<0.0001). During a mean follow-up of 1.5 +/- 1.2 years, 87 patients with severe AS reached the predefined end-point. Higher peak-exercise BNP level was associated with higher occurrence of adverse events (p<0.0001). In multivariate analysis, second and third tertiles of peak-exercise BNP (T2: HR=2.9; p=0.002 and T3: HR=5.3; p<0.0001, respectively) were powerful predictors of events compared with the first tertile. Further adjustment for resting BNP provided comparable results (T2: HR=2.8; p=0.003 and T3: HR=5.0; p<0.0001). This relationship persisted in both subsets of patients with low or high resting BNP. Conclusions This study reports that peak-exercise BNP level provides significant incremental prognostic value beyond what is achieved by demographic and echocardiographic data, as well as resting BNP level.