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

Abstract

Patients with severe aortic stenosis (AS), high mean gradient (HMG), and preserved left ventricular ejection fraction (LVEF) may present with paradoxical "low flow" (LF). 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. 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). 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. 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.