Clinical Application Of Transcatheter Aortic Valve Replacement In The Treatment Of Aortic Valve Disease

Transcatheter aortic valve replacement（TAVR）was originally considered as the last choice for patients with severe aortic stenosis（AS）who were inoperable but had to undergo aortic valve replacement.In foreign countries,with the progress of TAVR devices and the continuous deepening of clinical research,TAVR has become an alternative treatment strategy for patients with intermediate or low surgical risk.Compared with western countries,although TAVR started late in China,the volume of domestic TAVR and heart centers that can implement TAVR have increased rapidly in recent years.It was noted that Chinese patients with severe AS have different pathological characteristics,including a high proportion of bicuspid aortic valve（BAV）and severe valve calcification.Besides,influential clinical trials in Europe and the United States mostly use balloon-expandable prostheses,while domestic self-expanding prostheses are still the main transcatheter heart valves used in clinical practice.Therefore,the experience and guidelines of TAVR in Europe and the United States cannot fully guide the treatment of domestic severe AS patients.It is imperative to accumulate TAVR experience and evidence-based medical evidence for domestic devices and patients.BAV is considered as a relative contraindication for TAVR in the early stage due to its anatomical characteristics,such as irregular annulus,severe and asymmetrical calcification of the leaves and/or raphe,and dilatation of the ascending aorta.Foreign studies have preliminarily verified the feasibility of self-expanding Core Valve series prostheses and balloon-expandable SAPIEN series prostheses in the treatment of severely stenotic BAV.However,the proportion of BAV in China’s TAVR patients is significantly higher than that in foreign countries,and there is still lack of evidence on whether domestic self-expanding prostheses can be used in severely stenotic BAV.Therefore,it is necessary to evaluate the effect of domestic prostheses in patients with severely stenotic BAV.Pure aortic regurgitation（AR）has the anatomical characteristic of none calcification of the native aortic valve,which causes the difficulty of anchoring the prosthesis through the vascular approach.According to CT evaluation,our center has performed TAVR in selected patients who have anchorable structures at the aortic root with domestic Venus A valves.Moreover,the clinical symptoms of the patients were improved,and the prostheses’performance were excellent.We hope to further evaluate the feasibility,safety and efficacy of transfemoral transcatheter aortic valve replacement（TF-TAVR）for pure AR through rigorous patient selection and precise intraoperative manipulation.The whole study is divided into the following three parts.Part 1 Evaluation of the safety and efficacy of transcatheter aortic valve replacement using domestic aortic prostheses for severe aortic stenosisObjectiveTo evaluate the safety and efficacy of TAVR using domestic aortic prostheses in patients with severe AS.MethodsPatients with symptomatic severe AS who underwent TAVR with domestic prostheses at the Department of Cardiology,Xijing Hospital,Air Force Medical University from January 2016 to April 2020 were consecutively enrolled in a prospective study,and their baseline characteristics,intraoperative data and postoperative follow-up results of one month were analyzed.ResultsA total of 100 patients were enrolled,with an average age of（69.8±8.9）years,including 71 males（71.0%）and 82 cases（82.0%）with NYHA functional classⅢ/Ⅳ.The Society of Thoracic Surgeons-Predicted Risk of Mortality（STS-PROM）score was 4.0（2.0,6.9）%.51 cases（51.0%）had bicuspid aortic valve（BAV）.TAVR was successfully performed in all patients with 17 cases（17.0%）implanting an additional prosthesis.Immediately after the procedure,the mean pressure gradient（PGmean）of all patients decreased to less than 20 mm Hg,and PGmean was 7.1（5.0,10.0）mm Hg,and there was 1case（1.0%）with moderate paravalvular leakage.Before discharge,52 cases（52.0%）had conduction disturbances and arrhythmias,9 cases（9.0%）had permanent pacemaker implantation（PPM）,3 cases（3.0%）had acute kidney injury（AKI）,2 cases（2.0%）had coronary obstruction,1 case（1.0%）had myocardial infarction（MI）,1 case（1.0%）had stroke,1 case（1.0%）had cardiac tamponage due to temporary pacemaker perforation,and1 case（1.0%）had anesthesia complication.At one month,all-cause mortality was 6.0%（6/100）,including 2 cases with intermediate surgical risk and 4 cases with high surgical risk.Both the ratio of NYHA functional classⅢ/Ⅳ（5.0%vs.82.0%,P<0.001）and PGmean[（12.2±5.0）vs.（47.2±17.8）mm Hg,P<0.001]（1 mm Hg=0.133 k Pa）were significantly lower than those before TAVR.ConclusionsCompared to foreign literatures^[1,2]（the same type of studies including the full risk range of severe AS）,our study was basically consistent in terms of the incidence of stroke（1.0%vs.1.4%～3.1%）,MI（1.0%vs.0.5%～2.8%）,AKI（3.0%vs.0.7%～3.9%）and the one-month all-cause mortality（6.0%vs.2.1%～6.4%）,and the incidence of PPM was lower（9.0%vs.34.1%）.Postoperative hemodynamic indexes and cardiac function of the patients were significantly improved.Therefore,TAVR using domestic aortic prostheses in patients with severe AS was associated with favorable safety and efficacy.Part 2 Evaluation of the safety and efficacy of transcatheter aortic valve replacement for severely stenotic bicuspid aortic valveObjectiveTo evaluate the safety and efficacy of TAVR with domestic prostheses in patients with severely stenotic BAV.MethodsThe 100 patients with severe AS in the part one were divided into BAV group and tricuspid aortic valve（TAV）group according to valvular morphology,and baseline characteristics,intraoperative data and postoperative follow-up results of one month were compared between the two groups.ResultsBAV group had 51 cases（51.0%）and TAV group had 49 cases（49.0%）.Compared to TAV group,BAV group was younger[（67.1±8.6）vs.（72.7±8.4）years,P=0.002]and had larger proximal part of ascending aortic diameter[（39.7±5.7）vs.（36.0±4.2）mm,P<0.001],lower Society of Thoracic Surgeons-Predicted Risk of Mortality（STS-PROM）score[3.1（1.9,5.4）vs.5.9（2.6,12.3）%,P=0.002].In BAV group and TAV group,the incidence of 2nd prosthesis implantation were 15.7%,18.4%（P=0.721）,the incidence of moderate or severe paravalvular leakage were 2.0%,0（P=1.000）and the rate of device success were 82.4%,81.6%（P=0.925）,respectively.One-month all-cause mortality in BAV group and TAV group were 2.0%,10.2%（P=0.108）,respectively.Echocardiography showed that postoperative mean pressure gradient（PGmean）was higher in the BAV group[13.0（10.0,16.0）vs.9.0（7.0,14.0）mm Hg,P=0.003],but the PGmean decreased compared with that before TAVR in the two groups were similar[（36.7±16.6）vs.（36.2±17.5）mm Hg,P=0.893]（1 mm Hg=0.133 k Pa）.ConclusionsCompared with severely stenotic TAV,TAVR with domestic aortic prostheses to treat severely stenotic BAV was associated with similar procedural results and one month clinical results,and was safe and effective.Part 3 Evaluation of the safety and efficacy of transfemoral transcatheter aortic valve replacement for pure aortic regurgitationObjectiveTo investigate the feasibility,safety and efficacy of TF-TAVR for pure AR.MethodsPatients with pure AR who underwent TF-TAVR at our department from October2018 to January 2020 were consecutively enrolled in a prospective study,and their baseline characteristics,intraoperative data and postoperative follow-up results of one month were analyzed.ResultsA total of 26 patients were enrolled,with an average age of（69.4±7.8）years,including 22 males（84.6%）.All patients presented symptoms of left heart failure,including 23 cases（88.5%）with NYHA functional classⅢ/Ⅳ.Degree of aortic valve calcification:25 cases（96.2%）had none calcification,1 case（3.8%）had mild calcification.26 cases（100%）had tricuspid aortic valve（TAV）.TF-TAVR was successfully performed in all patients with 22 cases（84.6%）using 32 mm prosthesis and 18 cases（69.2%）implanting an additional prosthesis.Immediately after the procedure,there was 1 case（1.0%）with moderate paravalvular leakage（PVL）,and the degree of regurgitation in the other patients were reduced from severe to mild or less.Before discharge,19 cases（73.1%）had conduction disturbances and arrhythmias,3 cases（11.5%）had permanent pacemaker implantation（PPM）,2 cases（7.6%）had acute kidney injury（AKI）,2 cases（2.0%）were converted laparotomy for removal of the prosthesis after it fell off to the abdominal aorta during retraction.At one month,all-cause mortality was 7.6%（2/26）,the ratio of NYHA functional classⅢ/Ⅳwas significantly lower than that before TAVR（11.5%vs.88.5%,P<0.001）.Both the left ventricular end-diastolic volume（LVEDV）[（158.8±52.2）vs.（209.7±89.3）ml,P<0.001]and the left ventricular end-systolic volume（LVESV）[（85.0±36.9）vs.（112.7±62.1）ml,P<0.001]were significantly lower than those before TAVR.ConclusionsCompared to foreign literatures^[3-5],our study was basically consistent in terms of the incidence of PPM（11.5%vs.7.6%～24.4%）,AKI（7.6%vs.4.7%～11.8%）and the one-month all-cause mortality（7.6%vs.9.3%～23.1%）;The incidence of second valve implantation during TAVR was higher（69.2%vs.18.6%～24.4%）,because this study is an exploratory study and the enrolled patients have large annulus and mostly lack anchorable structure at the left ventricular outflow tract.The incidence of moderate or severe PVL after TAVR was lower（3.8%vs.18.8%～23.0%）.Patients’symptoms were relieved,cardiac function and degree of aortic valve regurgitation were significantly improved.Therefore,TF-TAVR was feasible,safety and efficacy in the treatment of pure AR.