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Explanation for 2012 ACCF/AATS/SCAI/STS Expert Consensus Document on Transcatheter Aortic Valve Replacement

Date:2016年12月14日 15:24
Transcatheter Aortic valve Replacement (TAVR) is a newly developed cardiac interventional technique. Since 2002 Cribier and other people implemented the first human TAVR, TAVR has developed rapidly. As of now, more than 50,000 patients worldwide have received TAVR treatment. TAVR is a team-based complex new technology that involves 12 areas (including cardiothoracic surgery, interventional medicine, cardiac anesthesia, imaging, nursing, neurology, heart failure, etc.), and requires the construction of a Multidisciplinary Heart Team (MDHT) model.  TAVR technology is becoming more and more mature, with more extensive clinical applications and the successive publication of some encouraging research results. However, there are no relevant documents to propose recommendations or requests for TAVR technologies. As a result, the American College of Cardiology Foundation (ACCF), the American Association for Thoracic Surgery (AATS), Society for Cardiovascular Angiography and Interventions (SCAI), and Society of Thoracic Surgeons (STS) have jointly released the TAVR Expert Consensus [1].
I. Indications and suggestions
 
The first highlight of the consensus is the mention of TAVR indications based on the latest findings and clinical practice. TAVR is recommended in patients with the following indications: ①with severe symptomatic, calcific aortic stenosis(CAS) of a trileaflet valve who have aortic and vascular anatomy suitable for TAVR and a predicted survival >12 months, and patients who have a prohibitive surgical risk as defined by an estimated 50% or greater risk of mortality or irreversible morbidity at 30 days or other factors such as frailty, prior radiation therapy, porcelain aorta, and severe hepatic or pulmonary disease,etc.②TAVR is a reasonable alternative to surgical AVR in patients at high surgical risk and who have aortic and vascular anatomy suitable for TAVR (PARTNER Trial Criteria: STS≥8%*) The consensus also mentions that in the future, TAVR might be recommended for the following people:patients with surgical valvular degeneration, bicuspid aortic valve, intermediate and low risk patients, and late-stage renal insufficiency. Most of the current studies select CAS patients with tricuspid aortic valve. Congenital bicuspid aortic valve CAS patients often have severe calcification of valve, with oval-shaped valve annulus.  Those patients are likely to have complications such as deformation, translocation and regurgitation of prosthetic valve after TAVR, so they were previously considered unsuitable for TAVR. But the recent small samples show good TAVR effects for CAS patients with bicuspid aortic valve [2]. Surgical aortic valve replacement (especially the biological valve) has a certain lifespan, and as time goes on, the prosthetic valve can deteriorate and cause valvular stenosis or dysfunction. It has been reported that the effect of TAVR (valve in valve technique) for this type of patient is also satisfactory [3, 4]. For patients with paravalvular leakage(PVL) after TAVR, TAVR can be performed again [5]. The long-term use of prosthetic valves after TAVR surgery also leads to valve degeneration and stenosis, and these patients can also be treated with TAVR [6] again. The CAS patient with aortic regurgitation is not a contraindication of TAVR. As long as CAS is the main lesion, it is still suitable for TAVR. Patients with severe coronary artery stenosis may be treated with percutaneous coronary intervention (PCI) before or after TAVR, and can receive TAVR operation after recovery from coronary artery stenosis. It is believed that with the improvement of the device and the progress of the research, TAVR indications will be wider and wider. 
II Clinical application evidence
 
The consensus reviews the latest registration studies and a large randomized controlled study( PARTNER) results, summarizing and evaluating the evidence of TAVR evidence-based medicine. These studies confirm that, in the right group, TAVR is generally safe and effective. TAVR can not only reduce the differential valve pressure, relieve the symptom, improve the quality of life and 6-minute walking distance, but also improve the function of myocardium, reverse the remodeling of left ventricle and decrease the level of brain natriuretic peptide(BNP). In addition, TAVR can also reduce the patient's mortality rate. In the study of SOURCE registration, the success rate of TAVR with Edwards SAPIEN valve stent via femoral artery is 93%, and the success rate of TAVR by apical route is 92%[7] In addition to a study of high-risk patients, the surgical success rate of CoreValve valve stents is more than 92%. TAVR early complications includes stroke, coronary artery occlusion, pacemaker implantation, vascular complications, kidney failure, heart rupture, cardiac tamponade, bleeding, aortic dissection, and death. The incidence rate of major complications in 30 days is 20%~40%. The mortality rate in hospitalization is 5%~8%. The mortality rate in 30 days is 8%~10%. The mortality rate in 1 year is 19%~24%. The proportion of patients who used Edwards SAPIEN valves and needed permanent pacemaker implantation is 1.8% ~ 8.5% And those who have used CoreValve is 9.1%~42.5%. The incidence rate of renal failure is below 3% and the incidence rate of stroke is 1%~5%. SOURCE registration research shows that the incidence rate of major bleeding events in TAVR via the apical pathway is higher than that via the femoral artery (3.9% vs. 2.3%). And the incidence rate of vascular-related complications via the femoral arterial pathway is higher than that via the apical pathway (the main events 11.3% vs. 2%, and the secondary events 10.4% vs.1%). It is believed that due to greater wound resulting from the previous use of 21F or even greater arterial vascular sheath and delivery system, the incidence rate of local vascular complication is higher. With the development and adoption of 18F delivery system, the incidence rate of this complication is obviously reduced [8]. With the accumulation of experience and the improvement of surgical skills and equipment, the incidence rate of other surgical complications will be reduced gradually. 
 
Although TAVR has been used in clinical practice since 2002, most of the previous clinical studies were small, single-center and observational studies, and almost all of them were published in the form of empirical summaries or registration studies. PARTNER research is the first large multicenter randomized controlled study in the field of TAVR research, which can be said to be of landmark significance. 
 
PARTNER-B studies have confirmed that TAVR is superior to traditional conservative therapy in patients with severe CAS, which are contraindications in surgical operations [9]; and PARTNER-A studies have confirmed that compared to surgical outcomes, TAVR are equally effective for patients with high risk for surgical operations with severe CAS [10]. The design is relatively rigorous and the results are encouraging, providing convincing evidence for the safety and efficacy of TAVR. The TAVR indications proposed by the consensus are basically based on the results of PARTENER study. However, PARTNER research results can only be applicable to a certain range of conditions, not suitable for arbitrary extrapolation. PARTNER has used Edwards Sapien valves, so the incidence rate of complete atrioventricular block and permanent pacemaker implantation is lower, and the results are not entirely applicable to CoreValve valve systems, and are not suitable for atypical cases like patients with coronary artery stenosis, severe peripheral vascular malformation, bicuspid aortic valve, non-calcified aortic valve stenosis, and severe aortic regurgitation. There’s a learning curve concerning the effect and safety of TAVR surgery, depending on the experience of the operator. Only in the experienced heart center and under the guidance of experienced experts, can TAVR surgery achieve similar results with PARTNER study. The efficacy and safety of TAVR surgery will be confirmed by longer follow-up and large randomized controlled studies in the future. In addition, the results are applicable to patients with surgical contraindications or high risks; and for patients with low surgical risk, the effect of TAVR and especially its comparison with surgical valve replacement needs further study. In several major registration studies, most selected patients are people with surgical contraindications or high surgical risks, but there are a considerable number of intermediate-risk patients (most of the patients with EuroScore>20 points, but also a considerable number of patients with EuroScore like 10~20 points), It can be seen in practice that there’s a development trend of performing TAVR on intermediate-risk patients. The consensus points out that before obtaining strong evidence, it is not advisable to perform TAVR on intermediate-risk patients.
III. Imaging Assessment Methods
TAVR preoperative assessment include dissection of aortic valve annulus, ascending aorta and peripheral arterial, to determine whether the patient is fit for TAVR and which type of valve should be selected. At present, the main imaging methods include two-dimensional and three-dimensional transthoracic echocardiography(TTE), transesophageal echocardiography (TEE), Multi-slice Spiral CT (MSCT), coronary arteriongraphy (CA), cardiac magnetic resonance (CMR), C-arm CT and so on. The consensus recommends the following assessment: ①Assessment of aortic annular size and shape (CT, CMR, 2D and 3D echocardiography);②Assessment of aortic valve for number of cusps, degree of calcification and valve area byplanimetry (CT, CMR, 2D and 3D echocardiography);③Measurement of the distance between annulus and coronary ostia (CT, CMR, 2D and 3D echocardiography);④Planning for precise coaxial alignment of the stent-valve along the centerline of the aortic valve and aortic root (CT); ⑤Assessment of aortic dimensions (2D and 3D echocardiography, CT or CMR) and atherosclerosis (echocardiography, CT, or CMR);⑥Assessment of dimensions and atherosclerosis of iliofemoral vessels (CT, MR, angiography); ⑦ Assessment of the extent of postoperative aortic valve insufficiency (echocardiography or CMR);⑧ Assessment of cerebral embolism (MRI). It should be added that preoperative assessment of coronary lesions should also be carried out. For patients with severe coronary stenosis, PCI can be conducted before or during TAVR. 
IV. Heart Center Qualification and Future Development Suggestions
 
The TAVR implementation heart centers requires certain qualifications, and consensus on this issue suggests: ① Heart Center that can implement TAVR must have conducted at least 50 cases of surgical aortic valve replacement within the past 12 months, and the interventional cardiologist must have experience with balloon aortic valvuloplasty; ②The main facility is the reconstructed cardiac catheterization room or hybrid room. The size of the reconstructed cardiac catheterization room should meet the requirements of placing anesthesia equipment, cardiac ultrasound equipment, intra-aortic balloon pumping (IABP) machine and extracorporeal circulation machine, and should conform to the standard of surgical aseptic operation. The hybrid room is a new type of operating room, which can be used for TAVR, coronary artery hybrid operation and aneurysm hybrid operation. The hybrid room should be approximately≥800 square feet(almost 74 square meters) and can meet the requirements of surgery, and should be accompanied by a DSA system, heart ultrasound equipment, CT or MRI machine. At present, the best hybrid room can meet the requirements of the cooperation of medical team and surgical team to perform surgery. Traditional coronary care unit (CCU) has extensive experience in monitoring hemodynamics in patients, but lacks experience in the treatment of the size puncture wounds and surgical wounds in patients with TAVR; while cardiac surgery intensive care unit has more experience in the treatment of wounds, but it lacks experience in the treatment of TAVR patients with rapid hemodynamic changes. Therefore, it is necessary to establish an independent monitoring area where TAVR patients are placed together in this area. Each center should make specific plans, including selection of preoperative patients, evaluation of complications treatment strategies, postoperative monitoring and nursing, and postoperative follow-up. It is believed that the formulation of these plans is conducive not only to the standardization of treatment, but also to the facilitation of clinical statistical research. The complication treatment strategy plan can serve as prevention plan to cope with complication occurrence. For more specific technical operation and institutional qualification requirements, please refer to another expert consensus [11].
 
The expert consensus also suggests the need for national registration studies that will help to observe the short-and long-term risks and benefits of TAVR patients, and track patient selection criteria, changes in surgical outcomes and equipment change. Registration studies may also be better able to cover the demographic characteristics and mortality rate of CAS patients undergoing surgery and drug therapy, so as to compare data from different treatment strategies to identify and select the best treatment options. The consensus also makes recommendations on the specific operation techniques of TAVR and treatment for complications. As most hospitals in our country do not carry out TAVR, this content will not be described in details here.
 
References
[1] Holmes DR Jr, Mack MJ, Kaul S, et al. 2002 ACCF/AATS/SCAI/STS expert conserisus document on transcatheter aortic valve replacement [J]. J Am Coll cardiol, 2012, 59: 1200 - 1254.
[2] Wijesinghe N, Ye J, Rodés-Cabau J, et al. Transcatheter aortic valve implantation in patients with bicuspid aortic valve stenosis [J]. JACC Cardiovasc Interv, 2010,3: 1122 – 1125.
[3] Seiffert M, Franzen O, Conradi L, et al. Series of transcatheter valve-in-valve implantations in high-risk patients with degenerated bioprostheses in aortic and mitral position [J]. Catheter Cardiovasc Interv, 2010, 76: 608 – 615.
[4] Wevv JG, Wood DA, Ye J, et al. Transcatheter valve-in-valve implantation for failed bioprosthetic heart valves [J]. Circulation, 2010, 121: 1848 – 1857.
[5] Rodés-Cabau J, Dumont E, Doyle D. “Valve-in-valve”for the treatment of paravalvular leaks following transcatheter aortic valve implantation [J]. Catheter Cardiovasc Interv, 2009, 74: 1116 – 1119.
[6] Hammerstingl C, Nickenig G, Grube E. Treatment of a degenerative stenosed CoreValve®  aortic bioprosthesie by transcatheter valve-in-valve insertion [J]. Catheter Cardiovasc Interv, 2012, 79: 748 – 755.
[7] Thomas M, Schymik G, Walther T, et al. Thirty-day results of the SAPIEN Aortic Bioprosthesis European Outcom (SOURCE) Registry: a European registry of transcatheter aortic valve implantation using the Edwards SAPIEN valve [J]. Circulation, 2010, 122(1): 62 – 69.
[8] Piazza N, Grube E, Gerckens U, et al. Procedural and 30-day out comes following transcatheter aortic valve implantation using the third generation (18 Fr CoreValve ReValving System: results from the multicenter, expanded evaluation registry 1-year following CE mark approval) [J]. Euro intervention, 2008,4: 242 – 249.
[9] Leon MB, Smith CR, Mack M, et al. Transcatheter aortic-valve implantation for aortic stenosis in patients who cannot undergo surgery [J]. N Engl J Med, 2010,363:1597 – 1607.
[10] Smith CR, Leon MB, Mack MJ, et al. Transcatheter versus surgical aortic-valve replacement in high-risk patients. N Engl J Med, 2011, 364: 2187 - 2198.
[11] Tommaso CL, Multisociety (AATS, ACCF, SCAI, and STS) expert consensus statement: operator and institutional requirements for transcatheter valve repair and replacement, part 1: transcatheter aortic valve replacement [J]. J Am Coll Cardiol. 2012, 59(22): 2028 – 2042.

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