4796Modulation of Exosomal microRNA in patients with severe Aortic Stenosis after Transcatheter Aortic Valve Implantation (TAVI)

Background: Transcatheter aortic valves (TAV) are being used increasingly in the treatment of severe aortic stenosis.However, there are complications, namely paravalvular regurgitation (PVR), which limit clinical benefits and need to be better understood in order to improve the selection of patients and types of prostheses.Better characterization of TAV geometry after the implant may be important in the understanding of these complications.Purpose: To compare TAV geometry according the type of prosthesis, evaluate predictors of geometrical changes and its impact on valvular performance.Methods: Retrospective study including patients consecutively submitted to TAV implantation: August/2007-October/2016.Exclusions: valve-in-valve procedures.Pre-procedural computed tomography (CT) was used to determine the dimensions of the native ring and calcium volume.Post-procedural CTs (3 months) were evaluated to assess prosthesis geometry: dimensions, eccentricity and expansion indexes.Statistical analysis: multivariate linear regression for determination of eccentricity and under-expansion predictors and multivariate binary logistic regression to determine PVR predictors.Results: A total of 283 patients were included (female 52.7%, mean age 79.1±7.6), 58% of whom were treated with self-expandable prosthesis (SEP).The balloon-expandable prosthesis (BEP) group had more coronary disease (64.2 vs 47.5%, p=0.008), with no differences in the remaining baseline characteristics.In the pre-procedure CT: the SEP group presented greater oversizing (35.7 vs 14.5%, p<0.001) and smaller native areas (425.9 vs 447.7 mm 2 , p=0.046), with no differences in calcium volume between groups.In the postprocedure CT, the SEP group had a higher implantation depth (7.7 vs 6.3mm, p=0.003), greater eccentricity (14.1 vs 6.0%, p<0.001) and under-expansion (65.8 vs 82.8%, p<0.001).Independent predictors of eccentricity were: tricuspid valves (p=0.031),calcium volume of the native ring/outflow tract (p=0.041) and SEP (p<0.001).The absence of type 2 diabetes mellitus (p=0.008),SEP (p<0.001) and calcium volume (p=0.003) were independent predictors of under-expansion.No correlation was observed between eccentricity or under-expansion and prosthetic valve gradients, but eccentricity was an independent predictor of PVR (adjusted OR 1.21, 95% CI 1.10-1.33,p<0.001). Conclusion(s):The implantation of SEP is associated with greater eccentricity and under-expansion.The eccentricity is influenced by calcium volume and type of prosthesis and it is associated with PVR.These factors should be considered in the selection of patients and types of TAV.