Peak Exercise Brain Natriuretic Peptide May Predict Poor Outcome in Patients With Asymptomatic Severe Aortic Stenosis
EBM Focus - Volume 9, Issue 43
The optimal timing of aortic valve replacement in patients with severe aortic stenosis is currently unclear, and risk stratification may help identify patients more likely to benefit. Several studies have shown that elevated resting brain natriuretic peptide (BNP) levels are associated with increased risk of poor outcome (Curr Cardiol Rep 2009 Mar;11(2):85, Circulation 2004 May 18;109(19):2302 full-text, Am J Cardiol 2005 Nov 15;96(10):1445, and Circulation 2007 Jun 5;115(22):2848 full-text). A recent study evaluated peak exercise BNP measurement for prediction of aortic valve replacement or death in 157 patients with asymptomatic severe aortic stenosis.
A total of 87 patients (55%) had aortic valve replacement or death during mean 1.5 years follow-up. The mean resting BNP level at baseline was 43 pg/mL overall (16 pg/mL in tertile 1, 45 pg/mL in tertile 2, and 101 pg/mL in tertile 3). The rate of event-free survival at 2 years in an adjusted analysis was:
- 81% for peak exercise BNP 6-46 pg/mL (reference)
- 48% for peak exercise BNP 47-94 pg/mL (p = 0.003 vs. reference)
- 18% for peak exercise BNP 95-956 pg/mL (p < 0.0001 vs. reference)
A peak exercise BNP >86 pg/mL was identified as the optimal cutoff for detection of aortic valve replacement or death. When compared to resting BNP, peak exercise BNP using optimal cutoffs was associated with an improved predictive performance of aortic valve replacement or death at 1 year (p < 0.0001). The results of this study suggest that for patients with asymptomatic severe aortic stenosis, use of peak exercise BNP may improve risk stratification compared to resting BNP. This may help identify patients who would benefit from closer observation and potentially earlier surgical intervention. Measurement of peak exercise BNP could be part of an exercise-stress echocardiography or a standard treadmill exercise test. However, a significant limitation is the lack of validation for a specific peak exercise BNP cutoff to use for risk stratification and patient management. In addition, there is limited other data on use of peak exercise BNP for risk stratification.