Abstract 18010: Prognostic Value of Exercise Plasma Brain Natriuretic Peptide Levels in Asymptomatic Aortic Stenosis

Abstract

BACKGROUND: Exercise stress echocardiography is useful in the risk stratification of patients with asymptomatic aortic stenosis (AS). Resting plasma brain natriuretic peptides (BNP) level is a good surrogate marker to predict the occurrence of symptoms and adverse events. The incremental prognostic value of BNP level during exercise is unknown. We aimed to identify the determinants of peak-exercise BNP level and to evaluate its prognostic value in asymptomatic AS patients.

METHODS: Comprehensive resting and exercise echocardiography were performed in 83 asymptomatic patients with at least moderate AS and preserved LVEF, prospectively included in 2 centers. Blood samples were collected both at rest and exercise. Valvulo-arterial impedance (Z_va) was calculated to assess LV global hemodynamic load.

RESULTS: Plasma BNP level increase from rest to exercise (76±123 vs. 92±134 pg/mL, p=0.003). After adjustment for age, gender, resting mean gradient (MG), relative wall thickness ratio and change in LVEF during exercise, the only independent determinants of peak-exercise BNP level were resting Z_va (β=0.36±0.17, p=0.04), resting stroke volume (β=0.02±0.01, p=0.03) and LV mass index (LVMi: β=0.01±0.004, p=0.008). During a mean follow-up of 2.3±1.7yrs, 44 patients underwent AVR only motivated by the development of symptoms or LV dysfunction. Peak-exercise BNP level (HR=1.53; 95%CI 1.1-2.1; p=0.01) was a significant predictor of outcomes. In multivariate analysis, after adjustment for age, gender, and exercise-induced increase in MG, peak-exercise BNP level (HR=1.50; 95%CI 1.04-2.2; p=0.03) was an independent predictor of outcomes. Even after adjustment for resting BNP level, peak-exercise BNP level (HR=3.51; 95%CI 1.4-8.3; p=0.009) remained the most powerful predictor of outcomes. Further adjustment for LVMi and resting Zva led to similar relationship between peak-exercise BNP and outcome (HR=3.18; 95% CI 1.2-8.0; p=0.02).

CONCLUSION: In asymptomatic AS patients, peak-exercise BNP level provides an incremental prognostic value beyond demographic and echocardiographic data, and resting BNP level. These findings lend support to the measurement of BNP during exercise to enhance risk stratification in asymptomatic patients with AS.