Abstract 13882: Myocardial Hypoperfusion in Severe Aortic Stenosis is Reversed by Aortic Valve Replacement

Abstract

Background: Myocardial hypoperfusion in severe aortic stenosis (AS) without obstructive coronary disease may be secondary to hemodynamic influences (and therefore readily reversible by aortic valve replacement[AVR]) or structural alterations in the left ventricle (LV) such as increased mass and reduction in capillary density. Aim: To evaluate the early effect of AVR on myocardial blood flow (MBF) in patients with severe symptomatic AS without flow-limiting coronary artery disease. Methods: Prospective case-control study of severe symptomatic AS without obstructive coronary disease referred for surgical or transcatheter AVR and propensity matched to a control cohort with unobstructed coronary arteries. Patients underwent adenosine stress cardiovascular magnetic resonance at baseline and 8-weeks (median) post-operatively. Histology from 9 myocardial septal biopsies taken at AVR were compared against necropsy controls (n=5). Results: 52 patients were included; 26 with severe AS (median [IQR] age 71[66-75], 73% male) and 26 age, sex and co-morbidity matched controls. In AS, peak velocity(Vmax) was 4.3m/s[4.1-4.5] and AVA 0.8cm 2 [0.6-0.9]. AS patients had greater LV mass and late gadolinium enhancement. AS patients had lower stress MBF than controls (1.63ml/g/min[1.38-2.08] vs 2.13[1.76-2.52], p=0.003) which increased to 1.97ml/g/min after AVR (p=0.7 post-AVR vs. Controls). This was driven by a 40% increase in subendocardial MBF (1.26ml/g/min[1.18-1.78] to 1.77[1.62-2.32]). Capillary density was reduced almost threefold in AS (495/mm 2 [407-686] vs 1376[1208-1579], p<0.001). Conclusions: Severe AS results in subendocardial hypoperfusion which is rapidly improved after AVR. There is a threefold reduction in capillary density, however factors related to elevated afterload (which is reduced by AVR) are the most influential.