|Year : 2021 | Volume
| Issue : 4 | Page : 166-171
Transcatheter aortic valve replacement for bicuspid aortic valve
Immaneni Sathyamurthy, Sai Satish
Department of Cardiology, Apollo Main Hospitals, Chennai, Tamil Nadu, India
|Date of Submission||03-Jul-2021|
|Date of Decision||25-Aug-2021|
|Date of Acceptance||26-Aug-2021|
|Date of Web Publication||25-Oct-2021|
Dr. Immaneni Sathyamurthy
Department of Cardiology, Apollo Main Hospitals, Chennai - 600 006, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Transcatheter aortic valve replacement (TAVR) is being routinely done in various centres for aortic stenosis due to tricuspid aortic valves. The number of TAVR procedures are increasing, but the data on bicuspid aortic valves (BAV) is scanty. BAV is commonest abnormality in general population and can progress to severe aortic stenosis. BAVs are a heterogeneous group due to anatomical variations and these valves are large, elliptical with asymmetric calcification. Echocardiography, multidetector CT scans help in diagnosing various phenotypes and in pre TAVR work up in sizing the device. The major issues regarding TAVR in BAVs are improper deployment of the valve , increased risk of strokes, paravalvular leaks, need for second device and requirement for pacemakers. With new generation devices the complication rates are coming down indicating their safe usage in BAVs. Data from TAVR registries and published studies have shown the applicability of TAVR in BAVs with acceptable outcomes.
Keywords: Aortic stenosis, bicuspid aortic valve, paravalvular leaks, transcatheter aortic valve replacement
|How to cite this article:|
Sathyamurthy I, Satish S. Transcatheter aortic valve replacement for bicuspid aortic valve. J Indian coll cardiol 2021;11:166-71
| Introduction|| |
Bicuspid aortic valves (BAVs) are a spectrum of abnormal valves consisting of two functional cusps with <3 zones of parallel appositions between cusps. BAV is the most common cardiac abnormality affecting 0.5%–2% of population., It can result in aortic stenosis (AS), aortic regurgitation (AR), aortopathy, aortic dissection, and prone to infective endocarditis (IE). Familial occurrence has been reported in 10% of first-degree relatives, and was found due to gene mutation of NOTCH-1. AR has been found to be due to the dilated, deformed aortic root, cuspal prolapse, associated myxoid degeneration of the cusps and can also as a result of IE.
BAV is a heterogeneous group due to variations in the aortic valve anatomy and the majority of them develop AS at a much younger age compared to tricuspid aortic valves (TAVs). In the past, most of them were undergoing surgical aortic valve replacement (SAVR) with good outcomes depending on their surgical risk score. At present, transcatheter aortic valve replacement (TAVR) is recommended in high-and intermediate-risk cases. Experience with TAVR is increasing with advancements in expertise, device technology, and hardware. Whether the same can be applied for BAVs safely with acceptable outcomes needs more data and evidence. In this review, we elucidated the basics and present the status of TAVR for BAVs. The data extracted from various registries and nonrandomized studies regarding imaging, the optimal sizing of the device, success rates, safety, and adverse outcomes with TAVR in BAV stenosis has been discussed. Newer studies in various risk groups on the application of TAVR in BAV patients are underway.
| Prevalence of Bicuspid Aortic Valve|| |
The prevalence of BAV in patients of AS who have undergone TAVR varied from 1.9% to 5.8%. The Society of Thoracic Surgeons (STS)/American College of Cardiology (ACC)/Trans Catheter valve Therapies (TCT) multicenter registry of 26,414 TAVR cases had BAV of 1.9%. German TAVI registry enrolled 4124 patients of which 3% were BAV while the Asian registry had 5.8% among 848 cases. Makkar et al. enrolled 81,822 consecutive patients from June 2015 to November 2018 of which 2726 were BAVs (3.3%). Of the 932 valves excised during SAVR the prevalence of BAV observed was 60% in the age group of 61–70, forty two percent in those between 71 and 80 years and 28% in those above 80 years confirming higher prevalence in younger subjects. In two of the randomized trials which included low-risk cases of BAV, the mean age observed was 10 years younger than the high-risk group., In patients with coarctation of the aorta, BAV was found in 20%.
| Basics of Bicuspid Aortic Valve|| |
Anatomical types of bicuspid aortic valve
Based on the number of raphes, cusps and their orientation, location of commissures Seivers and Schmiska. classified BAV into three types [Figure 1]. Type 0-nonraphe, Type I-only one raphe, Type II-two raphes. Type I is most common (90%). Based on fusion of raphe in relation to sinus, they were further sub-classified as left (L), right (R) or none (N). R-L fusion was found to be most common (80%), R-N (17%), and L-N fusion least common, seen in <3% cases. [Table 1] shows different phenotypes of BAV reported in some of the studies. In an international registry of 2118 BAV patients, the prevalence of AS, AR or both was found to be less in those without raphe, when there were 2 raphes the prevalence was higher than those with one raphe and among those with one raphe R-N type BAV had a higher incidence of AS.
|Table 1: Incidence of various types of bicuspid aortic valve in some of the studies|
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|Figure 1: Seiver's classification of bicuspid aortic valve. (Reproduced with permission from publisher)|
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Aortopathy in bicuspid aortic valve
The histochemical abnormalities noted were less fibrin content in the aortic wall, elastic fragmentation with increased collagen stiffness coupled with altered expression of matrix metalloproteinases. In addition, mechanical factors like eccentric jet across aortic valve due to different sizes of cusps may result in the altered shape of the aortic annulus. Aortic stiffness measured by pulse wave velocity (PWV) using velocity encoded magnetic resonance imaging revealed R–N fusion to manifest greater PWV than R-L fusion phenotype. The incidence of aortopathy was reported to be higher in those with R-N fusion than the most common R-L fusion phenotype.
The aortic root dilatation was classified by Fazel et al. into four types, Cluster I: Aortic root dilatation alone, Cluster II: Ascending aortic dilation, Cluster III: Ascending aortic dilatation tapering into the arch, Cluster IV: Ascending aorta with root dilatation. Sievers et al. studied 828 aortic valves excised during SAVR in BAVs taking into account ascending aortic configuration, valve hemodynamics and they modified Fazel's classification by combining Cluster II and III as class II [Figure 2]. They observed that AS due to BAVs showed localized ascending aortic dilatation only. Aortic root replacement is indicated if ascending aortic dimensions are ≥5.5 cms, those with severe AS with dimensions ≥5 cms or when dimensions showed progressive increase of ≥5 mm/year during follow up. In some cases, the aorta can be densely calcified called porcelain aorta. Aortopathy makes TAVR difficult as the porcelain aorta makes steering of the device difficult with higher chances for aortic rupture or dissections.
|Figure 2: Types of aortopathy in bicuspid aortic valve. (Reproduced with permission from publisher)|
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Natural history of bicuspid aortic valve
As asymptomatic subjects do not report, accurate data are not available in this subset. However, they can present with sudden onset of symptoms when complicated by IE or aortic dissection. AS of varying severity occur in 85% of cases by 5th decade, AR in 2%–15%, IE has been reported in 2% of cases during follow-up. The progress of aortopathy depends on the age, study population, comorbidities and the incidence reported was 20%–30%. In one study of 212 patients either with minimal or no symptoms when followed for 15% ±6 years 6% developed isolated severe AS requiring surgical intervention.
| Transcatheter Aortic Valve Replacement in Bicuspid Aortic Valve|| |
Routine echocardiography is needed for the evaluation of the severity of AS, left ventricular (LV) function, LV outflow tract, and mitral valve status. Routine two-dimensional transthoracic echocardiograms done to identify valvular phenotypes demonstrated a sensitivity of 78% and specificity of 96%. Multiplanar transesophageal echocardiograms revealed the sensitivity of 87% and specificity of 91%. With the addition of multidetector computed tomography (MDCT) the sensitivity improved to 94% and specificity to 100%.
Multidetector computed tomography
MDCT assessment is mandatory when TAVR is planned and showed high accuracy in detecting the valve anatomy compared to echocardiography,,,,, MDCT has been routinely done for aortic annular sizing and shown to correlate well with intraoperative sizing done during SAVR as observed in 84.6% of TAVs compared to 74% of BAVs. Post TAVR analysis with MDCT of 41 patients of BAV stenosis using balloon-expandable valves showed greater ellipticity and under expansion. Similar observations and high postprocedural gradients were reported with earlier-generation devices indicating the need for postprocedural MDCT assessment in all.
In bicuspid aortic valve anatomy and relationship with devices (BAVARD) multicenter registry it was shown that in addition to the area of the annulus, inter-commissural distance (ICD) measured 4 mm above the annulus helped in the accurate sizing of the device. In the BAVARD registry, 101 BAV stenosis were compared with 88 patients of TAV stenosis who had MDCT assessment pre- and post TAVR with newer generation devices in whom under expansion was constantly observed in BAVs. They described three types of configurations (1) Tubular configuration in whom mean aortic annular diameter (AAD) matched ICD, (2) Flared configuration where mean AAD was less than ICD, (3) Tapered configuration where the AAD was found larger than ICD. The authors recommended device oversizing in tubular type by 3%–4% the annulus, in flared type equal to annulus size and in tapered configuration sizing should be based on ICD.
Jilaihawi et al. reported a study of 130 cases of BAV stenosis in whom preprocedural MDCT was done but core-laboratory assessment could be done only in 91. They proposed a novel morphological classification on basis of the number of commissures, presence or absence of raphe into tricommissural bicuspid, bicommissural raphe type, and bicommissural nonraphe type and further sub-classified based on the leaflet orientation as coronary cusp fusion or mixed noncoronary-coronary cusp fusion [Figure 3]. They found bicommissural raphe-type to be the most common and observed marked geographical variations in its prevalence.
|Figure 3: Transcatheter aortic valve replacement – specific bicuspid aortic valve classification, Jilaihawi et al., (Reproduced with permission from the publisher)|
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Issues for transcatheter aortic valve replacement in bicuspid aortic valves
Although TAVR is being routinely done for TAVs, the number of BAVs subjected to this procedure is very much less. In BAV, the aortic orifice is elliptical, with asymmetric calcification associated with aortopathy which may lead to incomplete valve expansion, paravalvular leaks, and higher chances of need for pacemakers. In addition, coronary flow due to large valve leaflet, is a major concern. BAVs are common in the younger age group and long-term durability of the valve has not been established. SAVR has been established as the therapeutic modality for the past 4 decades, TAVR results should be comparable to the SAVR in various risk groups before it is approved as an indication for managing BAVs with stenosis.
Published reports on transcatheter aortic valve replacement in bicuspid aortic valve stenosis
The application of TAVR in BAV is under evolution. In various randomized trials, BAV patients were excluded even in the latest partner trials.,,, At present, Food and Drug Administration has approved TAVR in high and intermediate surgical risk cases. BAV constitutes a heterogeneous group due to anatomical variations such as large and elliptical aortic annulus making optimal conformability of the device difficult and a second device may be needed in some. Factors such as under expansion of valves, higher chances of prosthetic valve leaks (PVLs), and increased need for permanent pacemaker implantations (PPI) have been reported. The incidence of embolic strokes reported was high with TAVR, from Cedars Sinai medical center 30-day stroke rate reported was 2.4% for BAV compared to 1.6% for TAV. The exact sizing of the valve may pose a problem, as in some cases raphe may be incomplete or may not extend from the base to the tip of the leaflet and asymmetric calcification may be an added issue for optimal sizing of the device. BAV stenosis patients being younger compared to TAV stenosis, long-term durability of the device has not been established and coronary access for future percutaneous coronary interventions has to be considered.
The feasibility of TAVR in BAV stenosis was first reported by Wijesinghe et al. in 11 high-risk cases with balloon-expandable valves, only 2 had significant PVLs and 30-day mortality was 18%. In one study of high-risk BAV patients, TAVR with self-expanding valves showed 30-day survival rate of 93%, moderate PVL only in one, but the requirement of PPI was found to be high (40%). Hayashida et al. found no difference in 30-day mortality and PVLs in 21 BAV stenosis compared to 208 TAV stenosis who were subjected to TAVR and all of them had preprocedural MDCT assessment. One study of 21 high-risk BAV stenosis compared with 447 TAV stenosis showed that survival rates were less in BAV, they suggested careful selection of patients for TAVR may improve the outcomes. In the German aortic valve registry, 38 patients of BAV were compared with 1357 TAV who have undergone TAVR, reported higher rates of PVLs. Hence, the initial experience with smaller studies gave inconsistent results.
Mylotte et al. were first to report a large series of 139 cases of BAV stenosis subjected to TAVR with first-generation balloon-expandable valves in 48 and self-expandable in 91 and observed PVLs ≥ gr 2 in 28% and 1 year mortality of 17.5% without significant difference between balloon and self-expandable valve groups. They further observed that the incidence of PVLs was less when valve sizing was done by MDCT and recommended that either of the devices can be safely used in them. Yousef et al. reported from their multicentered retrospective registry analysis, the outcomes of TAVR in 108 BAVs and showed acceptable 30 days and 1 year mortality but 10% needed a second device. The bicuspid TAVR registry was the largest international multicentered registry of BAV from Europe, North America, and Asia Pacific regions and Yoon et al. reported their observations from the retrospective analysis of 301 consecutive intermediate-risk cases of BAV who have undergone TAVR, 71% with the first generation and 29% with newer generation devices and reported all-cause mortality at 30 days and 1 year were comparable between both the device groups. None had PVLs with newer generation devices and gave reassurance regarding their use to overcome the risk of PVLs. One sub study of TAVR in 51 high-risk patients of BAV using Sapien 3 valves reported 3.9% mortality at 30 days, none had significant PVL but 24% needed PPIs which was a major concern.
Yoon et al. from TAVR multicenter registry extracted data of 546 patients by propensity score matching compared BAV stenosis with TAV stenosis regarding procedural success, clinical outcomes, mortality and reported that BAVs had more conversions to SAVR, lesser success rates. In their retrospective analysis, they found that newer generation devices were used in 226 BAVs and 225 TAVs and observed more PVLs with early generation devices than new generation ones. They postulated the reduction of PVLs could be due to improved sealing properties of the newer devices.
Halim et al. in a retrospective analysis of 5412 cases of BAV stenosis from the multicentered STS/ACC/TCT registry found that these patients were younger with lower STS predicted risk, had larger annular sizes, device success rates were lower requiring even a second device and the incidence of PVLs were slightly higher. Though they observed higher postimplant gradients there was no significant difference in valve areas when compared to TAV stenosis. They did not find any difference as regards in-hospital mortality, the incidence of strokes, major bleeds but the need for pacemakers was higher in BAVs. From these reports and registry data, it can be inferred that BAVs were more prone to PVLs, the need for PPIs, and success rates observed were lower when compared to TAVs. Since the TAV numbers were much higher than BAVs, propensity matching or matching of co-variants were needed by the investigators for comparison in their retrospective analysis indicating a need for large multicentered randomized prospective comparative trials in this subset of patients.
Transcatheter aortic valve replacement in low risk bicuspid aortic valve stenosis
In ACC 2020, Forrest et al. presented data of a prospective study of 150 low-risk cases of BAV stenosis from 25 centers in the US, their average age was70 years with an STS score of 1.4% in whom supra-annular self-expanding valves were used and reported a success rate of 95.3%, death or disabling stroke in 1.3% at 30 days and none showed significant PVLs. It is evident from this study that TAVR can safely be recommended even in low-risk cases.
The International multicenter BAV-TAVR registry is an ongoing prospective observational study of 2000 patients, began recruiting in August 2016, and expected to be completed in 2028. They included those >18 years of age, New York Heart Association class ≥2, to be followed for 5 years after TAVR. The endpoints are death at 30 days, yearly mortality, the incidence of strokes, repeat hospitalizations, bleeding, vascular complications, and incidence of acute kidney injury. The results of this registry hopefully provide guidance and better understanding regarding TAVR in BAV stenosis.
| Future Directions|| |
One of the challenges for TAVR in BAV is mechanical obstruction to coronaries by the leaflets. Bioprosthetic Aortic Scallop International Laceration to prevent Iatrogenic Coronary Artery obstruction (BASILICA)procedure is a new innovation where an electrical wire is introduced through a catheter for sewing the original leaflet after splitting it into two to prevent obstruction to the coronary flow after prosthetic valve deployment. The electrified wire is used to produce controlled laceration of the leaflet. This procedure was attempted in 37 patients with 95% success. More studies are needed for its further application and approval.
| Conclusions|| |
Not all BAVs are similar. Patients of BAVs are heterogeneous group as the valve anatomy and morphology are variable with asymmetric calcification. Initial experience with TAVR showed higher chances of complications like PVLs, need for pacemakers and in some even need for a second device. MDCT sizing using the area of the annulus and ICD measured 4 mm above the annulus help in choosing an optimally sized device to improve the procedural outcomes. With newer generation devices the outcomes were comparable to TAV stenosis and the incidence of PVLs was found reduced. These patients are younger and the long-term durability of the device needs to be established. More data are accumulating in favor of TAVR in BAV stenosis. We are sure that the ongoing registry data will give more positive results and create confidence among the cardiologists to use TAVR in various risk subsets of BAVs.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Williams DS. Bicuspid aortic valve. J Insur Med 2006;38:72-4.
Ward C. Clinical significance of the bicuspid aortic valve. Heart 2000;83:81-5.
Mordi I, Tzemos N. Bicuspid aortic valve disease: A comprehensive review. Cardiol Res Pract 2012;2012:196037.
Cripe L, Andelfinger G, Martin LJ, Shooner K, Benson DW. Bicuspid aortic valve is heritable. J Am Coll Cardiol 2004;44:138-43.
Garg V, Muth AN, Ransom JF, Schluterman MK, Barnes R, King IN, et al
. Mutations in NOTCH1 cause aortic valve disease. Nature 2005;437:270-4.
Holmes DR Jr., Nishimura RA, Grover FL, Brindis RG, Carroll JD, Edwards FH, et al
. Annual outcomes with transcatheter valve therapy from the STS/ACC/TVT registry. J Am Coll Cardiol 2015;66:2813-23.
Bauer T, Linke A, Sievert H, Kahlert P, Hambrecht R, Nickenig G, et al.
Comparison of the effectiveness of transcatheter aortic valve implantation in patients with stenotic bicuspid versus tricuspid aortic valves (from the german TAVI registry). Amer J Cardiol 2014;113:518-21.
Yoon SH, Ahn JM, Hayashida K, Watanabe Y, Shirai S, Kao HL, et al
. Clinical outcomes following transcatheter aortic valve replacement in Asian population. JACC Interv 2016;9:926-533.
Makkar RR, Hoon SH, Leon MB, Chakravarty T, Rinaldi M, Shah PB, et al.
Association between transcatheter aortic valve replacement for bicuspid vs tricuspid aortic stenosis and mortality or stroke. JAMA 2019;321:2193-202.
Roberts WC, Ko JM. Frequency by decades of unicuspid, bicuspid, and tricuspid aortic valves in adults having isolated aortic valve replacement for aortic stenosis, with or without associated aortic regurgitation. Circulation 2005;111:920-5.
Seivers HH, Schmiska C. A classification system for the bicuspid aortic valve from 304 surgical specimens. J Thorac Cardiovasc Surg 2007;133:1226-33.
Mylotte D, Osnabrugge RL, Windecker S, Lefèvre T, de Jaegere P, Jeger R, et al
. Transcatheter aortic valve replacement in Europe: Adoption trends and factors influencing device utilization. J Am Coll Cardiol 2013;62:210-9.
Waksman R, Craig PE, Torguson R, Asch FM, Weissman G, Ruiz D, et al
. Transcatheter aortic valve replacement in low-risk patients with symptomatic severe bicuspid aortic valve stenosis. JACC Cardiovasc Interv 2020;13:1019-27.
Yoon SH, Lefèvre T, Ahn JM, Perlman GY, Dvir D, Latib A, et al.
Transcatheter aortic valve replacement with early- and new-generation devices in bicuspid aortic valve stenosis. J Am Coll Cardiol 2016;68:1195-205.
Yousef A, Simard T, Webb J, Rodés-Cabau J, Costopoulos C, Kochman J, et al.
Transcatheter aortic valve implantation in patients with bicuspid aortic valve: A patient level multi-center analysis. Int J Cardiol 2015;189:282-8.
Perlman GY, Blanke P, Dvir D, Pache G, Modine T, Barbanti M, et al.
Bicuspid aortic valve stenosis: Favorable early outcomes with a next-generation transcatheter heart valve in a multicenter study. JACC Cardiovasc Interv 2016;9:817-24.
Tchetche D, de Biase C, van Gils L, Parma R, Ochala A, Lefevre T, et al
. Bicuspid aortic valve anatomy and relationship with devices: The BAVARD multicenter registry. Circ Cardiovasc Interv 2019;12:e007107.
Kong WK, Delgado V, Poh KK, Regeer MV, Ng AC, McCormack L, et al
. Prognostic implications of raphae in bicuspid aortic valve anatomy. JAMA Cardiol 2017;2:285-92.
Fazel SS, Mallidi HR, Lee RS, Sheehan MP, Liang D, Fleischman D, et al
. The aortopathy of bicuspid aortic valve disease has distinctive patterns and usually involves the transverse aortic arch. J Thorac Cardiovasc Surg 2008;135:901-7.
Sievers HH, Stierle U, Hachmann RM, Charitos EI. New insights in the association between bicuspid aortic valve phenotype, aortic configuration and valve haemodynamics. Eur J Cardiothorac Surg 2016;49:439-46.
Michelena HI, Desjardins VA, Avierinos JF, Russo A, Nkomo VT, Sundt TM, et al.
Natural history of asymptomatic patients with normally functioning or minimally dysfunctional bicuspid aortic valve in the community. Circulation 2008;117:2776-84.
Brandenburg RO Jr., Tajik AJ, Edwards WD, Reeder GS, Shub C, Seward JB. Accuracy of 2-dimensional echocardiographic diagnosis of congenitally bicuspid aortic valve: Echocardiographic-anatomic correlation in 115 patients. Am J Cardiol 1983;51:1469-77.
Espinal M, Fuisz AR, Nanda NC, Aaluri SR, Mukhtar O, Sekar PC. Sensitivity and specificity of transesophageal echocardiography for determination of aortic valve morphology. Am Heart J 2000;139:1071-6.
Tanaka R, Yoshioka K, Niinuma H, Ohsawa S, Okabayashi H, Ehara S. Diagnostic value of cardiac CT in the evaluation of bicuspid aortic stenosis: Comparison with echocardiography and operative findings. AJR Am J Roentgenol 2010;195:895-9.
Hayashida K, Bouvier E, Lefèvre T, Chevalier B, Hovasse T, Romano M, et al.
Transcatheter aortic valve implantation for patients with severe bicuspid aortic valve stenosis. Circ Cardiovasc Interv 2013;6:284-91.
Jilaihawi H, Chen M, Webb J, Himbert D, Ruiz CE, Rodés-Cabau J, et al
. A bicuspid aortic valve imaging classification for the TAVR era. JACC Cardiovasc Imaging 2016;9:1145-58.
Patel PA, Gutsche JT, Vernick WJ, Giri JS, Ghadimi K, Weiss SJ, et al.
The functional aortic annulus in the 3D era: Focus on transcatheter aortic valve replacement for the perioperative echcardiographer. J Cardiothorac Vasc Anesth 2015;29:240-5.
Kawamori H, Yoon SH, Chakravarty T, Maeno Y, Kashif M, Israr S, et al.
Computed tomography characteristics of the aortic valve and the geometry of SAPIEN 3 transcatheter heart valve in patients with bicuspid aortic valve disease. Eur Heart J Cardiovasc Imaging 2018;19:1408-18.
Watanabe Y, Chevalier B, Hayashida K, Leong T, Bouvier E, Arai T, et al
. Comparison of multislice computed tomography findings between bicuspid and tricuspid aortic valves before and after transcatheter aortic valve implantation. Catheter Cardiovasc Interv 2015;86:323-30.
Leon MB, Smith CR, Mack M, Miller DC, Moses JW, Svensson LG, et al.
Transcatheter aortic-valve implantation for aortic stenosis in patients who cannot undergo surgery. N Engl J Med 2010;363:1597-607.
Smith CR, Leon MB, Mack MJ, Miller DC, Moses JW, Svensson LG, et al.
Transcatheter versus surgical aortic-valve replacement in high-risk patients. N Engl J Med 2011;364:2187-98.
Leon MB, Smith CR, Mack MJ, Makkar RR, Svensson LG, Kodali SK, et al.
Transcatheter or surgical aortic-valve replacement in intermediate-risk patients. N Engl J Med 2016;374:1609-20.
Reardon MJ, Van Mieghem NM, Popma JJ, Kleiman NS, Søndergaard L, Mumtaz M, et al.
Surgical or transcatheter aortic-valve replacement in intermediate-risk patients. N Engl J Med 2017;376:1321-31.
Wijesinghe N, Ye J, Rodés-Cabau J, Cheung A, Velianou JL, Natarajan MK, et al.
Transcatheter aortic valve implantation in patients with bicuspid aortic valve stenosis. JACC Cardiovasc Interv 2010;3:1122-5.
Himbert D, Pontnau F, Messika-Zeitoun D, Descoutures F, Détaint D, Cueff C, et al.
Feasibility and outcomes of transcatheter aortic valve implantation in high-risk patients with stenotic bicuspid aortic valves. Am J Cardiol 2012;110:877-83.
Costopoulos C, Latib A, Maisano F, Testa L, Bedogni F, Buchanan L, et al.
Comparison of results of transcatheter aortic valve implantation in patients with severely stenotic bicuspid versus tricuspid or nonbicuspid valves. Am J Cardiol 2014;113:1390-3.
Yoon SH, Bleiziffer S, De Backer O, Delgado V, Arai T, Ziegelmueller J, et al.
Outcomes in transcatheter aortic valve replacement for bicuspid versus tricuspid aortic valve stenosis. J Am Coll Cardiol 2017;69:2579-89.
Halim SA, Edwards FH, De D, Li Z, Mack MJ, Holmes DR, et al
. Outcomes of TAVR in patients with BCAV. Circulation 2020;141:1071-9.
Forrest JK, Kaple RK, Ramlawi B, Gleason TG, Meduri CU, Steven J, et al
. Transcatheter aortic valve replacement in bicuspid versus tricuspid aortic valves from the STS/ACC TVT registry. JACC Cardiovasc Interv 2020;13:1749-59.
Carroll JD, Mack MJ, Vermlapulli S, Hermann HC, Gleason TG, Hanzel G, et al
. STS – ACC TVT registry of transcatheter aortic valve replacement. JACC 2020;76:2492-516.
Khan JM, Greenbaum AB, Babaliaros VC, Rogers T, Eng MH, Paone G, et al
. The BASILICA trial: Prospective multicenter investigation of intentional leaflet laceration to prevent TAVR coronary obstruction. JACC Cardiovasc Interv 2019;12:1240-52.
[Figure 1], [Figure 2], [Figure 3]