Transcatheter Pulmonary Valve in Congenital Heart Disease.

Over the last 2 decades, experience with transcatheter pulmonary valve replacement (TPVR) has grown significantly and has become an effective and reliable way of treating pulmonary valve regurgitation, right ventricular outflow (RVOT) obstruction, and dysfunctional bioprosthetic valves and conduits. With the introduction of self-expanding valves and prestents, dilated native RVOT can be addressed with the transcatheter approach. In this article, the authors review the current practices, technical challenges, and outcomes of TPVR.

Transthoracic echocardiographic Doppler metrics in evaluating bioprosthetic tricuspid valve dysfunction.

PURPOSE: There is currently limited information on the utility of transthoracic echocardiography (TTE)-derived Doppler parameters for assessing bioprosthetic tricuspid valve (BTV) dysfunction. Our study aimed to establish the precision and appropriate reference ranges for routinely collected transthoracic Doppler parameters in the assessment of BTV dysfunction. METHODS: We retrospectively evaluated 100 BTV patients who underwent TTE. Based on redo surgical confirmation or more than 2 repeat TTE or transesophageal echocardiography (TEE) examinations, patients were allocated to normal (n = 61), regurgitant (n = 24), or stenotic (n = 15) BTV group. Univariate and multivariate binary logistic regression were performed to identify TTE Doppler parameters that detected BTV dysfunction. RESULTS: The VTI ratio (VTITV/VTILVOT) was the most accurate Doppler parameter for detecting BTV dysfunction, with a ratio of >2.8 showing 84.6% sensitivity and 90.2% specificity. VTI ratio > 3.2, mean gradient (MGTV) > 6.2 mmHg and pressure half-time > 218 ms detected significant BTV stenosis, with sensitivities of 100%, 93.3% and 93.3% and specificities of 82.4%, 75.3% and 87.1%, respectively. After multivariate analysis, the VTI ratio > 2.8 (OR = 9.00, 95% CI = 2.13-41.61, p = .003) and MGTV > 5.1 mmHg (OR = 6.50, 95% CI = 1.69-27.78, p = .008) were the independent associations of BTV dysfunction. With these cutoff values, 75.0%-92.2% of normal and 62.5%-96.0% of dysfunctional BTV were identified. CONCLUSIONS: Doppler parameters from TTE can accurately identify BTV dysfunction, particularly with VTI ratio > 2.8 and MGTV > 5.1 mmHg, to assess the need for additional testing with TEE.

The α-Gal KO Mouse Animal Model is a Reliable and Predictive Tool for the Immune-Mediated Calcification Assessment of Heart Valve Bioprostheses.

BACKGROUND: Recent studies highlighted the presence of anti-α-Gal antibodies in patients implanted with commercial bioprosthetic heart valves (BHVs). BHVs expose residual α-Gal xenoantigen and their recognition by the circulating anti-Gal antibodies leads to opsonization of the device's tissue component with the consequent triggering of a deterioration pathway that culminates with calcification. Small animal models such as mice and rats have been broadly involved in the in vivo testing of biomaterials by subcutaneous implantation, especially for the effectiveness of BHVs anti-calcific treatments. However, since models employed for this purpose express α-Gal antigen, the implantation of BHVs' leaflets does not elicit a proper immunological response, so the calcification propensity may be dramatically underestimated. METHODS: An α-Gal knockout (KO) mouse model has been created, using the CRISP/Cas9 approach, and adopted to assess the calcification potential of commercial BHVs leaflets through the surgical implantation in the back subcutis area. Calcium quantification was performed by inductively coupled plasma analysis; immune response against the BHVs leaflets and α-Gal silencing was evaluated through immunological assays. RESULTS: Two months after the implantation of commercial BHV leaflets, the anti-Gal antibody titers in KO mice doubled when compared with those found in wild-type (WT) ones. Leaflets explanted from KO mice, after one month, showed a four-time increased calcium deposition concerning the ones explanted from WT. The degree of silencing of α-Gal varied, depending on the specific organ that was assessed. In any case, the animal model was suitable for evaluating implanted tissue responses. CONCLUSIONS: Such mouse model proved to be an accurate tool for the study of the calcific propensity of commercial BHVs leaflets than those hitherto used. Given its reliability, it could also be successfully used to study even other diseases in which the possible involvement of α-Gal has been observed.

Twenty-year experience following aortic valve replacement in patients younger than 60 years of age.

OBJECTIVE: Reports on long-term outcomes of surgical aortic valve replacement (AVR) for patients aged < 60 years are scarce in Japan. Hence, we aimed to evaluate these outcomes in patients aged < 60 years. METHODS: Between March 2000 and December 2020, 1477 patients underwent aortic valve replacement. In total, 170 patients aged < 60 years who underwent aortic valve replacement were recruited. Patients aged < 18 years were excluded. Patient data collected from the operative records and follow-up assessments were reviewed. RESULTS: The mean age was 49 ± 9 years, and 64.1% of patients were male. One-hundred-and-fifty-two patients (89.4%) underwent aortic valve replacement with a mechanical valve and 18 (10.6%) with a bioprosthetic valve. The mean follow-up period was 8.1 ± 5.5 years. No operative mortality occurred, and in-hospital mortality occurred in one patient (0.6%). Ten late deaths occurred, with seven cardiac-related deaths. The overall survival rate was 95.4 ± 1.7%, 93.9 ± 2.3%, 90.6 ± 3.9%, and 73.2 ± 11.8% at 5, 10, 15, and 20 years, respectively. Freedom from major bleeding was 96.4 ± 1.6% at 5, 10, and 15 years, and 89.0 ± 7.3% at 20 years. Freedom from thromboembolic events was 98.7 ± 1.3%, 97.3 ± 1.9%, 90.5 ± 4.5%, and 79.0 ± 11.3% at 5, 10, 15, and 20 years, respectively. Freedom from valve-related reoperation was 99.4 ± 0.6% at 5 years, 97.8 ± 1.7% at 10 and 15 years, and 63.9 ± 14.5% at 20 years. CONCLUSIONS: Patients aged < 60 years undergoing aortic valve replacement with a high mechanical valve implantation rate had favorable long-term outcomes.

Comparison of apixaban versus aspirin for the prevention of latent bioprosthetic aortic valve thrombosis: study protocol for a prospective randomized trial.

BACKGROUND: The optimal antithrombotic strategy early after aortic valve replacement surgery with a biological valve remains controversial due to lack of high-quality evidence. Either oral anticoagulants or acetylsalicylic acid should be considered for the first 3 months. Hypo-attenuated leaflet thickening on cardiac computed tomography has been associated with latent bioprosthetic valve thrombosis and may be prevented with anticoagulation. We hypothesize that anticoagulation with apixaban is superior to single antiplatelet therapy with acetylsalicylic acid in reducing hypo-attenuated leaflet thickening of bioprosthetic aortic valve prostheses. METHODS: In this prospective, open-label, randomized trial, patients undergoing isolated aortic valve replacement surgery with rapid deployment bioprosthetic valves will be randomized. The treatment group will receive 5 mg of apixaban twice a day for the first 3 months and 100 mg of acetylsalicylic acid thereafter. The control group will be administered 100 mg of acetylsalicylic acid once a day, indefinitely. After the 3-month treatment period, a contrast-enhanced electrocardiogram-gated cardiac computed tomography will be performed to identify hypo-attenuated leaflet thickening of the bioprosthetic valve. The primary objective of the study is to assess the impact of apixaban on the prevention of hypo-attenuated leaflet thickening at 3 months. The secondary and exploratory endpoints will be clinical outcomes and safety profiles of the two strategies. DISCUSSION: Antithrombotic therapy after aortic valve replacement is used to prevent valve thrombosis and systemic thromboembolism. Latent bioprosthetic valve thrombosis is a precursor of clinically significant prosthetic valve dysfunction or thromboembolic events. The hallmark feature of latent bioprosthetic valve thrombosis is hypo-attenuated leaflet thickening on cardiac computed tomography. Subclinical leaflet thrombosis occurs frequently in bioprosthetic aortic valves, more commonly in transcatheter than in surgical valves. There is no evidence on the effect of direct oral anticoagulants on the incidence of hypo-attenuated leaflet thickening after surgical aortic valve replacement with rapid deployment bioprostheses. TRIAL REGISTRATION: ClinicalTrials.gov NCT06184113. Registered on December 28, 2023.

Computer-Assisted Transcatheter Mitral Valve Implantation for Valve-in-Valve Procedures.

Transcatheter mitral valve-in-valve is an alternative to high-risk reoperation on a failing bioprosthesis. It entails specific challenges such as left ventricular outflow tract obstruction. We propose a patient-specific augmented imaging based on preoperative planning to assist the procedure. Valve-in-valve simulation was performed to represent the optimal level of implantation and the neo-left ventricular outflow tract. These data were combined with intraoperative images through a real-time 3D/2D registration tool. All data were collected retrospectively on one case (pre and per-procedure imaging). We present for the first time an intraoperative guidance tool in transcatheter mitral valve-in-valve procedure.

Surgical Technique And Clinical Implications Of Transcatheter Aortic Valve Bioprosthesis Explantation.

There has been a worldwide rapid adoption of transcatheter aortic valve replacement (TAVR) as an alternative to surgical aortic valve replacement (SAVR) for patients with severe aortic stenosis. Currently, more TAVR explants with SAVRs are performed than TAVR-in TAV. TAVR explantation is a technically hazardous procedure mainly due to significant aortic neo-endothelialization which incorporates the TAVR valve. Surgical techniques for TAVR explantation are not well established and surgeon experience at present is limited. In this manuscript, we describe our technique for surgical explantation of transcatheter aortic bioprosthesis. Familiarity with the procedure and its clinical implications is essential for all cardiac surgeons.

Examining the typical hemodynamic performance of nearly 3000 modern surgical aortic bioprostheses.

OBJECTIVES: The objective of this analysis was to assess the normal haemodynamic performance of contemporary surgical aortic valves at 1 year postimplant in patients undergoing surgical aortic valve replacement for significant valvular dysfunction. By pooling data from 4 multicentre studies, this study will contribute to a better understanding of the effectiveness of surgical aortic valve replacement procedures, aiding clinicians and researchers in making informed decisions regarding valve selection and patient management. METHODS: Echocardiograms were assessed by a single core laboratory. Effective orifice area, dimensionless velocity index, mean aortic gradient, peak aortic velocity and stroke volume were evaluated. RESULTS: The cohort included 2958 patients. Baseline age in the studies ranged from 70.1 ± 9.0 to 83.3 ± 6.4 years, and Society of Thoracic Surgeons risk of mortality was 1.9 ± 0.7 to 7.5 ± 3.4%. Twenty patients who had received a valve model implanted in fewer than 10 cases were excluded. Ten valve models (all tissue valves; n = 2938 patients) were analysed. At 1 year, population mean effective orifice area ranged from 1.46 ± 0.34 to 2.12 ± 0.59 cm2, and dimensionless velocity index, from 0.39 ± 0.07 to 0.56 ± 0.15. The mean gradient ranged from 8.6 ± 3.4 to 16.1 ± 6.2 mmHg with peak aortic velocity of 1.96 ± 0.39 to 2.65 ± 0.47 m/s. Stroke volume was 75.3 ± 19.6 to 89.8 ± 24.3 ml. CONCLUSIONS: This pooled cohort is the largest to date of contemporary surgical aortic valves with echocardiograms analysed by a single core lab. Overall haemodynamic performance at 1 year ranged from good to excellent. These data can serve as a benchmark for other studies and may be useful to evaluate the performance of bioprosthetic surgical valves over time. CLINICAL TRIAL REGISTRATION NUMBER: NCT02088554, NCT02701283, NCT01586910 and NCT01531374.

On the role of aortic valve architecture for physiological hemodynamics and valve replacement, Part I: Flow configuration and vortex dynamics.

Aortic valve replacement has become an increasing concern due to the rising prevalence of aortic stenosis in an ageing population. Existing replacement options have limitations, necessitating the development of improved prosthetic aortic valves. In this study, flow characteristics during systole in a stenotic aortic valve case are compared with those downstream of two newly designed surgical bioprosthetic aortic valves (BioAVs). To do so, advanced three-dimensional fluid-structure interaction simulations are conducted and dedicated analysis methods to investigate jet flow configuration and vortex dynamics are developed. Our findings reveal that the stenotic case maintains a high jet flow eccentricity due to a fixed orifice geometry, resulting in flow separation and increased vortex stretching and tilting in the commissural low-flow regions. One BioAV design introduces non-axisymmetric leaflet motion, which reduces the maximum jet velocity and forms more vortical structures. The other BioAV design produces a fixed symmetric triangular jet shape due to non-moving leaflets and exhibits favourable vorticity attenuation, revealed by negative temporally and spatially averaged projected vortex stretching values, and significantly reduced drag. Therefore, this study highlights the benefits of custom-designed aortic valves in the context of their replacement through comprehensive and novel flow analyses. The results emphasise the importance of analysing jet flow, vortical structures, momentum balance and vorticity transport for thoroughly evaluating aortic valve performance.

Optimization of Enzymatic and Chemical Decellularization of Native Porcine Heart Valves for the Generation of Decellularized Xenografts.

One of the most important medical interventions for individuals with heart valvular disease is heart valve replacement, which is not without substantial challenges, particularly for pediatric patients. Due to their biological properties and biocompatibility, natural tissue-originated scaffolds derived from human or animal sources are one type of scaffold that is widely used in tissue engineering. However, they are known for their high potential for immunogenicity. Being free of cells and genetic material, decellularized xenografts, consequently, have low immunogenicity and, thus, are expected to be tolerated by the recipient's immune system. The scaffold ultrastructure and ECM composition can be affected by cell removal agents. Therefore, applying an appropriate method that preserves intact the structure of the ECM plays a critical role in the final result. So far, there has not been an effective decellularization technique that preserves the integrity of the heart valve's ultrastructure while securing the least amount of genetic material left. This study demonstrates a new protocol with untraceable cells and residual DNA, thereby maximally reducing any chance of immunogenicity. The mechanical and biochemical properties of the ECM resemble those of native heart valves. Results from this study strongly indicate that different critical factors, such as ionic detergent omission, the substitution of Triton X-100 with Tergitol, and using a lower concentration of trypsin and a higher concentration of DNase and RNase, play a significant role in maintaining intact the ultrastructure and function of the ECM.

Bioprosthetic mitral valve thrombosis: the role of cardiac CT in diagnosis and guiding the management.

A patient in his 60s with a bioprosthetic aortic and mitral valve replacement presented with dyspnoea, tiredness and dizziness 2 years postoperatively. Transthoracic echocardiography showed mitral valve stenosis and increased pulmonary artery pressure suggesting bioprosthetic valve failure. Cardiac CT confirmed the diagnosis of bioprosthetic mitral valve thrombosis. Treatment with anticoagulation resulted in a remarkable improvement of the valve area and gradient and complete resolution of the thrombus. Herein, we report a case of rare bioprosthetic mitral valve thrombosis.

The Ongoing Debate: Longevity of Biological Valves in Pulmonary Position.

BACKGROUND: In patients with tetralogy of Fallot (ToF) or ToF-like anatomy, factors possibly impacting the longevity of biological valves in the pulmonary position were investigated. METHOD: Between 1997 and 2017, 79 consecutive hospital survivors with a median age of 8.7 years (range: 0.2-56.1 years; interquartile range [IQR]: 14.8 years) with ToF or ToF-like anatomy underwent surgical implantation of Contegra (n = 34), Hancock (n = 23), Perimount (n = 9), pulmonary homograft (n = 9), and miscellaneous (n = 4) conduits. The median internal graft diameter was 19 mm (range: 11-29 mm; IQR: 8 mm) which refers to a median z-score of 0.6 standard deviation (SD) (range: -1.8 to 4.0 SD; IQR: 2.1 SD). RESULTS: The median time of follow-up was 9.4 years (range: 1.1-18.8 years; IQR: 6.0 years). Thirty-nine patients (49%) underwent surgical (n = 32) or interventional (n = 7) pulmonary valve re-replacement. Univariate Cox regression revealed patient age (p = 0.018), body surface area (p = 0.004), internal valve diameter (p = 0.005), and prosthesis z-score (p = 0.018) to impact valve longevity. Multivariate Cox regression analysis, however, did not show any significant effect (likely related to multicollinearity). Subgroup analysis showed that valve-revised patients have a higher average z-score (p = 0.003) and younger average age (p = 0.007). CONCLUSION: A decreased longevity of biological valves in the pulmonary position is related to younger age, lower valve diameter, and higher z-score. Because valve size (diameter and z-score) can be predicted by age, patient age is the crucial parameter influencing graft longevity.

[Catheter-based and surgical treatment for aortic valve diseases]. / Katheterbasierte und operative Therapie bei Aortenvitien.

The pathophysiology of aortic valve diseases is of predominantly degenerative nature, characterized by calcific aortic valve stenosis, which is associated with a reduction in prognosis. The prevalence of aortic valve insufficiency also increases with advancing age. Timely causal treatment is crucial in the management of aortic valve diseases. Following the indication for intervention, the heart team plays a central role in evaluating the results and making therapeutic decisions that consider the patient's preferences. In the assessment of treatment options, considerations regarding the long-term perspective are particularly crucial, especially in younger patients. The most common therapeutic approach for aortic valve diseases is the introduction of a new valve prosthesis. In the majority of cases, this is now achieved through catheter-based implantation of a bioprosthetic heart valve, known as transcatheter aortic valve implantation (TAVI). Open surgical aortic valve replacement (AVR) is favored in younger patients with low surgical risk or in the case that TAVI is not feasible. In AVR, both biological and the longest-lasting mechanical prosthesis types are used. Surgical repair techniques are primarily applied in cases of aortic valve regurgitation. Notably, TAVI, as well as surgical procedures for the treatment of aortic valve diseases, have undergone significant advancements in recent years, including expanded indications for TAVI and, on the surgical side, in particular the development of minimally invasive surgical techniques.

Combined transcatheter aortic valve and tricuspid valve-in-valve implantation in a patient with a mitral mechanical prosthesis.

Despite progressively uncommon in Western countries, rheumatic heart disease still portrays a significant global burden. In elderly or high-surgical risk patients, plurivalvular disease may require a complex percutaneous approach. Transcatheter aortic valve implantation (TAVI) in patients with previous monoleaflet mitral prosthesis is challenging due to interference between the aortic valve and the rigid mitral mechanical prosthesis "ring." Prior cases report the use of CoreValve or Edwards Sapien aortic valves in patients with adequate mitro-aortic distance. Performing a second major procedure, such as tricuspid valve-in-valve (TVIV), sequentially during a single percutaneous intervention, increases treatment complexity. An 83-year-old woman with rheumatic heart disease, with previous implantation of a Bjork-Shiley monoleaflet mitral prosthesis, and Carpentier-Edwards 29 tricuspid bioprosthesis presented with decompensated heart failure due to severe aortic stenosis and tricuspid bioprosthesis stenosis. After HeartTeam discussion, the patient was deemed as inoperable due to a prohibitive surgical risk. As an alternative, a TAVI (Navitor FlexNav) and a transcatheter TVIV replacement (Edwards Sapiens 3 Ultra) were discussed and proposed, with both techniques being performed sequentially in a single procedure. TAVI in a patient with a previous monoleaflet mitral mechanical prosthesis and TVIV may be a feasible approach in inoperable patients with plurivalvular disease.

Long-Term Outcomes of Bioprosthetic Valves in the Mitral Position: A Pooled Meta-Analysis of Reconstructed Time-to-Event Individual Patient Data.

Bioprosthetic mitral valve replacement (bMVR) use is increasing; however, data regarding long-term durability are lacking. We sought to perform a reconstructed individual patient data meta-analysis from published Kaplan-Meier curves to ascertain survival, freedom from valve degeneration, and reoperation in studies published since 2010. We explored the effects of age and valve type (bovine pericardial or porcine valve) on outcomes. We searched MEDLINE, OVID, Embase, and Cochrane CENTRAL for studies reporting at least 3 years of follow-up after bMVR and published since 2010. The Risk Of Bias In Non-randomised Studies of Interventions (ROBINS-I) tool was used to assess methodologic quality. Kaplan-Meier curves were digitized to extract individual patient data and reconstructed estimates for overall survival, freedom from structural valve deterioration (SVD), and freedom from reoperation. A total of 20 studies (16,465 patients) were included. A total of 9 studies reported on porcine valves, 6 reported on bovine, and 7 did not specify the valve type. The overall survival after bMVR at 15 years was 40% (confidence interval 38% to 42%), freedom from reoperation at 15 years was 79% (confidence interval 76% to 82%), and freedom from SVD at 15 years was 64% (58% to 70%). Freedom from SVD was improved in the 70+ years age group (93% up to 25 years, hazard ratio 6.6 [2.5 to 17] for 18 to 59 vs >70 years, p <0.0001). There was no difference in valve durability or survival between bovine pericardial or porcine valves. In this meta-analysis of patients who underwent bMVR using newer generation valves, the inverse relation between age and SVD was reiterated in the 70+ years age group. The prosthesis type made no difference in the outcomes.

Improved Hemodynamics With Self-Expanding Compared to Balloon-Expandable Transcatheter Aortic Valve Implantation in Small Annulus Patients: A Propensity-Matched Analysis.

Patients with small aortic annuli (SAA) pose a challenge in patients undergoing aortic valve replacement because of the potential for prosthesis-patient mismatch (PPM). This study aimed to compare the clinical and hemodynamic outcomes of self-expandable valve (SEV) versus balloon-expandable valve (BEV) transcatheter aortic valve implantation (TAVI) in patients with severe aortic stenosis and SAA. All patients who underwent TAVI for severe native aortic stenosis with a SAA between January 2018 and December 2022 were retrospectively included in the study from a single center. Propensity score matching was performed to balance the baseline characteristics. Bioprosthesis valve dysfunction was based on modified Valve Academic Research Consortium 3 criteria. A total of 1,170 TAVI procedures were performed between 2018 and 2022. After applying the exclusion criteria, 332 patients reported a SAA at computed tomography scan, and the matching created 109 balanced pairs. Echocardiographic data at discharge showed higher mean transvalvular gradients (p <0.001), higher grades of mitral regurgitation (p = 0.029), and lower ejection fraction (p <0.043) in BEVs than SEVs. At follow-up, significant differences favoring the SEV group regarding bioprosthesis valve dysfunction were observed (p = 0.002), especially in terms of severe PPM (p = 0.046) and at least moderate structural valve deterioration (p = 0.040). In conclusion, TAVI in patients with SAA using a BEV was associated with lower valve areas, higher mean pressure gradients, and PPM (including severe) than a SEV. Short- and midterm all-cause and cardiac-related mortality did not differ between the 2 groups. Future randomized studies with extended follow-ups are warranted to validate these outcomes.

Aortic Regurgitation, Time to Aortic Valve Reintervention, and Mortality in Degenerated Trifecta Versus Non-Trifecta Bioprosthesis.

On July 31, 2023, the Trifecta valve was withdrawn from the market after concerns regarding early (≤5 years) structural valve deterioration (SVD), mainly as aortic regurgitation (AR). Our aim was to determine the timing, mechanism, and impact of bioprosthetic SVD in patients who underwent redo aortic valve replacement (redo-AVR) with either redo-SAVR or valve-in-valve transcatheter aortic valve replacement (TAVR) using Trifecta versus other bioprosthetic valves. Patients who underwent redo-AVR for SVD at our institution were categorized into 2 groups based on the valve type: Trifecta versus non-Trifecta. Multivariate Cox proportional hazard model and Kaplan-Meier curves were used to compare mortality. A total of 171 patients were included; 58 (34%) had previous SAVR with a Trifecta valve and 113 (66%) with non-Trifecta valve. A total of 103 patients (60%) underwent valve-in-valve TAVR and 68 redo-SAVR (40%). The age, gender, and Society of Thoracic Surgeons score were similar between Trifecta and non-Trifecta groups. In patients with bioprosthetic valves requiring redo-AVR, Trifecta valves had an earlier onset of greater than moderate AR (4.5 vs 11.9 years, p <0.001) and earlier time to redo-AVR (5.5 vs 12 years, p <0.001). AR was more common as the mechanism of SVD in Trifecta versus non-Trifecta valves (55.2% vs 30.1%, p = 0.006). All-cause adjusted mortality from index SAVR was higher in the Trifecta than in non-Trifecta group (hazard ratio 4.1, 95% confidence interval 1.5 to 11.5, p = 0.007). In conclusion, compared with non-Trifecta valves, Trifecta valves exhibit early SVD primarily as AR and progress rapidly to significant SVD requiring redo-AVR. Mortality is significantly higher with Trifecta than in non-Trifecta valves, potentially impacting the results of SAVR versus TAVR studies.

Self-Expanding or Balloon-Expandable TAVR in Patients with a Small Aortic Annulus.

BACKGROUND: Patients with severe aortic stenosis and a small aortic annulus are at risk for impaired valvular hemodynamic performance and associated adverse cardiovascular clinical outcomes after transcatheter aortic-valve replacement (TAVR). METHODS: We randomly assigned patients with symptomatic severe aortic stenosis and an aortic-valve annulus area of 430 mm2 or less in a 1:1 ratio to undergo TAVR with either a self-expanding supraannular valve or a balloon-expandable valve. The coprimary end points, each assessed through 12 months, were a composite of death, disabling stroke, or rehospitalization for heart failure (tested for noninferiority) and a composite end point measuring bioprosthetic-valve dysfunction (tested for superiority). RESULTS: A total of 716 patients were treated at 83 sites in 13 countries (mean age, 80 years; 87% women; mean Society of Thoracic Surgeons Predicted Risk of Mortality, 3.3%). The Kaplan-Meier estimate of the percentage of patients who died, had a disabling stroke, or were rehospitalized for heart failure through 12 months was 9.4% with the self-expanding valve and 10.6% with the balloon-expandable valve (difference, -1.2 percentage points; 90% confidence interval [CI], -4.9 to 2.5; P<0.001 for noninferiority). The Kaplan-Meier estimate of the percentage of patients with bioprosthetic-valve dysfunction through 12 months was 9.4% with the self-expanding valve and 41.6% with the balloon-expandable valve (difference, -32.2 percentage points; 95% CI, -38.7 to -25.6; P<0.001 for superiority). The aortic-valve mean gradient at 12 months was 7.7 mm Hg with the self-expanding valve and 15.7 mm Hg with the balloon-expandable valve, and the corresponding values for additional secondary end points through 12 months were as follows: mean effective orifice area, 1.99 cm2 and 1.50 cm2; percentage of patients with hemodynamic structural valve dysfunction, 3.5% and 32.8%; and percentage of women with bioprosthetic-valve dysfunction, 10.2% and 43.3% (all P<0.001). Moderate or severe prosthesis-patient mismatch at 30 days was found in 11.2% of the patients in the self-expanding valve group and 35.3% of those in the balloon-expandable valve group (P<0.001). Major safety end points appeared to be similar in the two groups. CONCLUSIONS: Among patients with severe aortic stenosis and a small aortic annulus who underwent TAVR, a self-expanding supraannular valve was noninferior to a balloon-expandable valve with respect to clinical outcomes and was superior with respect to bioprosthetic-valve dysfunction through 12 months. (Funded by Medtronic; SMART ClinicalTrials.gov number, NCT04722250.).