Abstract 16609: Histological and Molecular Fingerprints of Low-Gradient Aortic Stenosis

Background: Low-gradient aortic stenosis (LGAS) is associated with a worse prognosis and high operative risk compared to aortic stenosis (AS) with normal left ventricular (LV) ejection fraction (EF). We aimed to investigate histological and molecular correlations of impaired LV function in LGAS. Methods: Transmural biopsies during aortic valve replacement were obtained from 5 consecutive patients (pt) with LGAS, 7 pt with AS, while 4 donor hearts before transplantation served as controls. Preoperative echocardiography quantified LV global and regional function. The fraction of cardiac interstitial tissue, the intracellular volume fraction of myofibriIs and myofiber diameters were determined by light microscopic morphometry. Expression of sarcoplasmic-endoplasmic reticulum calcium ATPase SERCA-2a and of natrium/calcium exchanger NCX-1 were assessed by immunohistochemical staining. Results: LGAS was echocardiographically characterized by decreased EF, radial LV strain and -strain rate. Histologically, no di...