Abstract 11057: Preoperative Symptomatic Status and Outcome After Valve Replacement in Severe Aortic Stenosis is Correlated With Capillary Density, Degree of Fibrosis and Cardiomyocyte Hypertrophy
Background A significant number of severe aortic stenosis (AS) patients remain symptomatic after valve replacement (AVR). We hypothesized that a reduced capillary density, extensive fibrosis and decreased cardiomyocyte (CM) density contribute to heart failure in symptomatic pressure-overloaded hearts despite unloading.
Methods and Results Echocardiography, CMR, and cardiopulmonary exercise testing for peak oxygen consumption (VO2max) were performed in patients with isolated severe AS without significant coronary artery disease (CAD) at baseline and 12 months follow-up (FU). Functional parameters were correlated with histological analysis on peri-operative biopsies from the LV outflow tract in 10 asymptomatic AS patients (AAS) and 18 symptomatic AS patients (SAS). The AAS (age 62±8ys, mean aortic valve gradient (ΔP) 49±10mmHg, LV mass 159 ±33gr, EF 65±6% and VO2max 96±22% at baseline) performed well after surgery. SAS did not differ from AAS with respect to age, ΔP, LV mass and EF at the time of AVR, but had significantly reduced VO2max. Of these, 12 patients showed functional and structural improvement at FU (SAS +) (ΔVO2max +345 ml/min, Δ%predicted VO2max+20%) while 6 patients did not improve or even deteriorated (SAS-) (Δ%predicted VO2max-8%). Histological analysis (Table 1) revealed significantly increased collagen content in SAS- after FU compared to SAS+. CM density was significantly decreased in SAS- than in SAS+ and in AAS. CM hypertrophy was significantly higher in SAS- than in SAS+ and AAS, whereas capillary density was significantly decreased in SAS- compared to SAS+ and to AAS. In conclusion Failure to improve functional capacity after AVR for severe AS correlates with enhanced myocardial replacement fibrosis, CM hypertrophy and impaired capillary density. Pre-operative evaluation of myocardial tissue perfusion, degree of fibrosis using advanced imaging techniques might serve as prognostic indicators and help to improve timing of AVR
- © 2012 by American Heart Association, Inc.