Computed Tomography Characteristics Of Self-expanding Valve Stent Morphology And Association With Hemodynamics,prognosis After Transcatheter Aortic Valve Replacement

Background and objective:Transcatheter aortic valve replacement(TAVR)is an alternative method of surgical aortic valve replacement(SAVR)to treat patients with severe aortic stenosis.The indication of TAVR has been extended from high to intermediate risk patients,and now even expanded to low-risk patients.Computed tomography(CT)has shown advantages in assessing the position,the expansion and deformation of the valve stent,and previous studies implied that the incomplete expansion and asymmetry of the valve were related to paravalvular regurgitation and hemodynamics.The primary objective of this study was to evaluate the CT morphological features of self-expanding valve after TAVR and the association of valve morphology with hemodynamics,paravaluvalr regurgitation and prognosis.Methods:We retrospectively analyzed from March 1,2013 to February 28,2018,patients who underwent TAVR at the Second Affiliated Hospital of Zhejiang University School of Medicine.Exclusive criteria were as follows:(1)valves other than CoreValve and Venus A;(2)during the procedure patients received another valve implantation;(3)lack of CT images before discharge or 1-year post TAVR.After CT image reconstruction,measurements were performed on 4 planes,and the circumferential expansion ratio,area expansion ratio and eccentricity of each plane were calculated according to the stent parameters.The measurement planes were as follows:(1)Plane A,the bottom of the prosthesis(2)Plane B,the nadir of leaflets;(3)Plane C,the central coaptation;(4)Plane D,the commissures.Baseline,preoperative CT measurements,procedure-related data,follow-up echocardiography,and clinical outcomes were collected.Results:A total of 104 patients were enrolled in this study.The mean age of the patients was 76 years old,males accounted for 60.6%,and the STS score was 5.5(3,8-9.3)%.48 patients(46.2%)used CoreValve and 56(53.8%)used Venus A.The plane expansion ratio after self-expanding valve was shown as Plane A?Plane B<Plane C?Plane D,and eccentricity was shown as Plane A?Plane B>Plane C>Plane D.The Plane B and Plane C area expansion ratio of Venus A valves were higher than CoreValve(89.1(80.2-96.8)%vs 78.4(71.0-85.7)%,P<0.001;105.6(94.0-112.1)%vs 95.6(87.0-99.6)%,P<0.001),there were no difference in the morphology of the other planes.The protective factor of Plane A expansion was the implantation depth LCC(OR=1.372),the risk factor of Plane B expansion was the minimum diameter of the sinus tube junction(OR=0.667).The risk factor of Plane C expansion was the implantation depth LCC.(OR=0.863).The protective factor of Plane D expansion was the area of ascending aorta(OR=1.002),and the risk factor was the implantation depth NCC(OR=0.862).Patients with incomplete expansion(<100%)in Plane C had a higher rate of Paravalvular regurgitation(PVR)than those in the complete expansion(? 100%)group(63.5%vs 40.6%,P=0.046),and there were no difference in mean transvalvular pressure difference,maximum transvalvular flow velocity,and aortic valve area at 1 year after TAVR.The area expansion ratio of Plane C is a protective factor for the mild or moderate PVR at 1 year after TAVR(OR=0.961).There were no differences between these two groups in postoperative 1-year clinical outcomes.The area expansion ratio of Plane C in patients with bicuspid aortic valve was higher than that of patients with tricuspid aortic valve(101.2(94.9-110.8)%vs 96.2(88.4-105.3)%,P=0.03).The area expansion ratio of Plane C and Plane D of Type 0 BAY patients were higher than that of TAV patients(103.5(97.5-110.9)%vs 96.1(88.2-105.0)%,P=0.02;99.2(96.3-103.8)%vs 93.2(85.6-102.6)%,P=0.02),while Type 1 BAY did not differ from stent morphology with TAV.Conclusion:This study found that there were significant differences in the stent morphology of the different planes in the self-expanding valve after TAVR.The expansion ratio was shown as Plane A?Plane B<Plane C?Plane D,and eccentricity was as Plane A?Plane B>Plane C>Plane D.The Plane B and Plane C of the Venus A valve expanded better than the Core Valve,and the Plane C of the BAV patient expanded better than the TAV.Furthermore,it was found that the protective factor of Plane A expansion was the implantation depth,the risk factor of Plane B expansion was the minimum diameter of the sinus-tubular junction;the risk factor of Plane C expansion was the implantation depth.While the protective factor of Plane D expansion was the area of ascending aorta,and the risk factor of Plane D was the implantation depth NCC Furthermore,the expansion ratio of Plane C was a protective factor for patients with mild or moderate PVR 1 year after TAVR,but it was not associated with hemodynamics.These results provided the evidence of the correlation between valve stent morphology and valve function.