Cardiovascular magnetic resonance imaging in severe aortic stenosis: impact of surgical and trans-catheter aortic valve replacement on reverse remodelling and fibrosis

Abstract

Introduction: Aortic stenosis (AS) is the commonest valvular lesion in the developed world and is associated with adverse cardiac remodelling. With its excellent accuracy and reproducibility, cardiovascular magnetic resonance (CMR) imaging is an ideal tool to assess cardiac remodelling and reverse remodelling following surgical aortic valve replacement (SAVR) and transcatheter aortic valve implantation (TAVI). The aims of this thesis were: 1) to evaluate gender differences in AS and following aortic valve replacement, 2) to evaluate the incidence of post-procedural myocardial infarction following SAVR and TAVI, 3) to describe the immediate effect of TAVI on reverse remodelling and 4) to assess the impact of TAVI-induced left bundle branch block (LBBB) . Methods: Between January 2009 and April 2015, patients with severe AS undergoing either TAVI or SAVR were prospectively recruited. Patients underwent comprehensive 1.5T CMR evaluation pre-procedure, prior to hospital discharge and 6m post-procedure. Results: 1) Women with severe AS have a lower indexed left ventricular (LV) mass than men (65.3± 18.4 vs. 81.5±21.3g/m2, p<0.001). 6m following valve replacement, LV mass regression is similar between genders (men 21.7±10.1 vs. women 18.4±11.0%, p=0.121). 2) Myocardial infarction (MI) is more frequent following SAVR than TAVI (n=10 (26%) vs. n=3 (5%), p=0.004). 3) Over 10% of LV mass regression occurs prior to hospital discharge following TAVI and is more pronounced in the absence of myocardial fibrosis (p=0.005). 4) TAVI-induced LBBB is associated with a reduced LVEF 6m following TAVI compared with those with a narrow QRS (-2.1±6.9 vs. +4.6±7.8%, p=0.002). Conclusions: TAVI and SAVR are associated with favourable cardiac reverse remodelling which does not differ according to gender and begins prior to hospital discharge. SAVR is associated with a higher incidence of post-procedural MI than TAVI. TAVI-induced LBBB should be avoided where possible due to its unfavourable effects on cardiac reverse remodelling