Relationships between cardiac biomarkers and heart function in aortic stenosis patients scheduled for surgical aortic valve replacement

Objective: To investigate whether the plasma levels of four biomarkers can help predict systolic dysfunction of either ventricle and left ventricular diastolic dysfunction in patients suffering severe aortic stenosis and scheduled for aortic valve replacement. Background: There has recently been an increasing interest for the use of biomarkers in the diagnosis, prognostication, and follow-up of heart diseases. Apart from the N-terminal pro B-type natriuretic peptide (NT-proBNP), the relationships between these biomarkers and the different aspects of heart function remain poorly investigated in patients eligible for cardiac surgery. It is plausible that some biomarkers more specifically reflect the dysfunction of one or the other ventricle, or diastolic dysfunction. Methods: This unspecified and therefore exploratory analysis of a previously published prospective observational trial adheres to the applicable EQUATOR guidelines. After Ethics Committee approval and written informed consent, the plasma levels of NT-proBNP, soluble isoform of suppression of tumorigenicity 2 (sST2), Galectin 3, and growth differentiation factor (GDF-15) were measured in an arterial blood sample drawn before induction of anesthesia in 179 patients undergoing aortic valve replacement for aortic stenosis. The monotonic interactions between the biomarkers and various echocardiographic measurements performed during the pre-cardiopulmonary bypass transesophageal echo exam were investigated using the Spearmann correlation coefficient. Whenever a significant correlation was observed, the ability of the biomarker to predict abnormal heart function was investigated using the area under the receiver operating curve (AUROC). Results: Significant correlations were observed between the level of NT-proBNP and the ejection fraction of the left ventricle (LVEF) (ρ=-0.31, P<0.001), or its global longitudinal strain (GLS) (ρ=-0.40, P<0.001). The NT-proBNP was also correlated with the left atrial (LA) volume (ρ=0.23, P=0.03) and the LA reservoir strain (ρ=-0.33, P<0.001). The correlations between the e/e’ ratio and both the NT-proBNP (ρ=0.38, P<0.001) and the GDF-15 (ρ=0.24, P=0.006) were significant. No correlation was observed between Galectin 3 and sST2 and any of the echo parameters. The ability of NT-proBNP to predict an LVEF < 50% (AUROC=0.66) and a GLS > -20% (AUROC=0.63) was weak. The ability of NT-proBNP to predict an e/e’ ratio > 14 was moderate (AUROC=0.71) and not significantly improved by the addition of GDF-15 (AUROC=0.69, P=0.44) Conclusions: The NT-proBNP had a weak to moderate ability to predict both systolic and diastolic dysfunction of the left ventricle in our patient population. Apart from a weak relationship between GDF-15 and diastolic dysfunction, no significant relationship was observed between any of the other markers tested and the echocardiographic measurements in our patient population.