Simple Lab Tests to Better Stratify Low Flow and Low Gradient AS Patients

Combining B-type natriuretic peptide (BNP) and high-sensitive cardiac troponin T measures undeniably helps to better stratify severe aortic stenosis patients with low flow and low gradient.  Many patients in these conditions clearly benefit from a transcatheter aortic valve replacement (TAVR) procedure, and for others it is simply useless, and given its high cost, better stratification could be of great use.  

We did know high BNP is associated with increased mortality in severe aortic stenosis patients (especially those with low flow and low gradient) but we ignored the incremental prognosis value of high-sensitive troponin level in these patients.

The study included 98 patients (74±10 years; 75% men) with low flow and low gradient aortic stenosis (ejection fraction <50% and/or stroke volume index  <35 ml/m², mean gradient <40 mmHg, indexed aortic valve area <0.6 cm²/m²), prospectively enrolled in the TOPAS trial (Truly or Pseudo-Severe Aortic Stenosis).

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Patients were divided in three groups according to these levels: group 1, BNP <550 pg/ml and troponin <15 ng/ml; group 2, BNP ≥550 pg/ml or troponin ≥15 ng/ml; and group 3, with elevated levels (BNP ≥550 pg/ml and troponin ≥15 ng/ml).

Primary end point was all cause mortality.

27% of patients were found in group A, 40% in group B and 33% in group C. Two- year mortality rate was significantly higher in group C (41 ± 9%) compared against group B (23 ± 7%) and group A (5 ± 4%), (p<0.002 for all combinations).

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Group B did not show significant differences in mortality, regardless the higher level was BNP or troponin.

After adjusting for age, type of treatment (valve replacement or conservative treatment) associated coronary disease or ejection fraction, group C combined markers continued to be independent predictors of mortality (more than 4 times higher; p=0.023). Group B showed higher mortality compared to group A, though not significantly higher.

Conclusion

This study shows the use of combining BNP and troponin levels to clearly stratify these patients that, not long ago, were considered similar. High levels of these markers in the context of severe aortic stenosis with low flow and low gradient could determine the futility of aortic valve replacement.

Original title: B-Type Natriuretic Peptide and High-Sensitivity Cardiac Troponin for Risk Stratification in Low-Flow, Low-Gradient Aortic Stenosis. A Substudy of the TOPAS Study.

Reference: Abdellaziz Dahou et al. J Am Coll Cardiol Img 2018, Article in press.

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