Clinical outcome, echocardiographic assessment, neurohormonal and collagen turnover markers in low-flow severe aortic stenosis with high transvalvular gradient

Abstract

INTRODUCTION: Patients with severe aortic stenosis (AS), high mean gradient (HMG), and preserved left ventricular ejection fraction (LVEF) may present with paradoxical "low flow" (LF). OBJECTIVES: The aim of the study was to assess the potential effect of cardiac collagen metabolism on the HMG/LF phenomenon in patients with severe AS and to determine a clinical and echocardiographic pattern of these patients. PATIENTS AND METHODS: We assessed a clinical status of 89 patients, aged over 64 years, with severe AS, HMG, and preserved LVEF (≥50%). Cardiac structure and function as well as systemic arterial hemodynamics were assessed with echocardiography, conventional Doppler, and tissue Doppler imaging. Moreover, plasma levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP), procollagen III N-terminal propeptide (PIIINP), carboxyterminal telopeptide of collagen type I, matrix metallopeptidase 9, and inhibitor of matrix metalloproteinase type 1 were evaluated. We analyzed 2 groups of patients: with normal flow (stroke volume index [SVI], ≥35 ml/m2; n = 70) and with LF (SVI, <35 ml/m2; n = 19). RESULTS: Patients with LF were older, had a larger left atrium and left atrial volume index, smaller aortic valve area, lower energy loss index, stroke work, mitral flow E velocity, mitral annular E' and S' velocities and systemic arterial compliance, higher relative left ventricular wall thickness, E/E', systemic arterial resistance and valvulo-arterial impedance. We observed a correlation between SVI and NT-proBNP, PIIINP, and selected parameters of cardiac structure and function. CONCLUSIONS: In patients with severe AS, HMG and preserved LVEF, the LF is related to a more severe obstruction, altered aortic hemodynamics, cardiac dysfunction, and higher blood levels of NT-proBNP. An inverse association between PIIINP and SVI may indicate enhanced tissue fibrosis as an underlying pathology. Copyright © by Medycyna Praktyczna, Kraków 2014.