Author + information
- Received December 19, 2016
- Revision received February 28, 2017
- Accepted February 28, 2017
- Published online May 1, 2017.
- John G. Webb, MDa,∗ (, )
- Michael J. Mack, MDb,
- Jonathon M. White, MDc,
- Danny Dvir, MDd,
- Philipp Blanke, MDe,
- Howard C. Herrmann, MDf,
- Jonathon Leipsic, MDe,
- Susheel K. Kodali, MDg,
- Raj Makkar, MDh,
- D. Craig Miller, MDi,
- Philippe Pibarot, DVM, PhDj,
- Augusto Pichard, MDk,
- Lowell F. Satler, MDk,
- Lars Svensson, MD, PhDl,
- Maria C. Alu, MSg,
- Rakesh M. Suri, MD, DPhilm and
- Martin B. Leon, MDg
- aDivision of Cardiology, St. Paul’s Hospital, Vancouver, British Columbia, Canada
- bDepartment of Cardiothoracic Surgery, Baylor Scott and White Health, Plano, Texas
- cDepartment of Cardiovascular Medicine, Cleveland Clinic, Cleveland, Ohio
- dDivision of Cardiology, University of Washington, Seattle, Washington
- eDepartment of Radiology, St. Paul’s Hospital, Vancouver, British Columbia, Canada
- fPerelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- gStructural Heart and Valve Center, Center for Interventional Vascular Therapy, Division of Cardiology, Columbia University Medical Center, New York, New York
- hHeart Institute, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California
- iDepartment of Cardiothoracic Surgery, Stanford University, Stanford, California
- jDepartment of Medicine, Laval University, Quebec Heart and Lung Institute, Quebec City, Quebec, Canada
- kDivision of Interventional Cardiology, Medstar Washington Hospital Center, Washington, DC
- lSydell and Arnold Miller Family Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio
- mDepartment of Thoracic and Cardiovascular Surgery, Cleveland Clinic, Cleveland, Ohio
- ↵∗Address for correspondence:
Dr. John G. Webb, St. Paul’s Hospital, 1081 Burrard Street, Vancouver, British Columbia V6Z 1Y6, Canada.
Background Early experience with transcatheter aortic valve replacement (TAVR) within failed bioprosthetic surgical aortic valves has shown that valve-in-valve (VIV) TAVR is a feasible therapeutic option with acceptable acute procedural results.
Objectives The authors examined 30-day and 1-year outcomes in a large cohort of high-risk patients undergoing VIV TAVR.
Methods Patients with symptomatic degeneration of surgical aortic bioprostheses at high risk (≥50% major morbidity or mortality) for reoperative surgery were prospectively enrolled in the multicenter PARTNER (Placement of Aortic Transcatheter Valves) 2 VIV trial and continued access registries.
Results Valve-in-valve procedures were performed in 365 patients (96 initial registry, 269 continued access patients). Mean age was 78.9 ± 10.2 years, and mean Society of Thoracic Surgeons score was 9.1 ± 4.7%. At 30 days, all-cause mortality was 2.7%, stroke was 2.7%, major vascular complication was 4.1%, conversion to surgery was 0.6%, coronary occlusion was 0.8%, and new pacemaker insertion was 1.9%. One-year all-cause mortality was 12.4%. Mortality fell from the initial registry to the subsequent continued access registry, both at 30 days (8.2% vs. 0.7%, respectively; p = 0.0001) and at 1 year (19.7% vs. 9.8%, respectively; p = 0.006). At 1 year, mean gradient was 17.6 mm Hg, and effective orifice area was 1.16 cm2, with greater than mild paravalvular regurgitation of 1.9%. Left ventricular ejection fraction increased (50.6% to 54.2%), and mass index decreased (135.7 to 117.6 g/m2), with reductions in both mitral (34.9% vs. 12.7%) and tricuspid (31.8% vs. 21.2%) moderate or severe regurgitation (all p < 0.0001). Kansas City Cardiomyopathy Questionnaire score increased (mean: 43.1 to 77.0) and 6-min walk test distance results increased (mean: 163.6 to 252.3 m; both p < 0.0001).
Conclusions In high-risk patients, TAVR for bioprosthetic aortic valve failure is associated with relatively low mortality and complication rates, improved hemodynamics, and excellent functional and quality-of-life outcomes at 1 year. (The PARTNER II Trial: Placement of AoRTic TraNscathetER Valves [PARTNER II]; NCT01314313)
Surgical aortic valve replacement (SAVR) has long been the gold standard for the management of severe aortic stenosis (AS). Recent years have seen a trend towards the use of bioprostheses as a result of the increased risk of bleeding and thrombotic complications with mechanical prostheses (1–3). Combined with an aging population, these factors are likely to result in increasing numbers of patients presenting with structural degeneration of aortic bioprostheses. Reoperation for failed surgical valves carries important risks (4–6); however, valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) has recently emerged as a less invasive treatment for patients with degenerated bioprostheses (7). We present the 1-year follow-up results of a large cohort of high-risk patients who underwent VIV TAVR for failing surgical aortic bioprostheses.
The PARTNER (Placement of Aortic Transcatheter Valves) 2 trial was a prospective, multicenter study that enrolled patients with symptomatic AS. This study included a nested registry of patients with degenerated surgical aortic bioprostheses who were at high risk of complications during reoperation. Following the enrollment of a maximum of 100 patients in the nested registry, additional patients were enrolled in a continued access registry.
Patients were required to have a bioprosthesis suitable for VIV treatment with either a 23- or 26-mm Sapien XT transcatheter heart valve (THV) (Edwards Lifesciences Corp., Irvine, California). Severe aortic stenosis was defined as an effective orifice area (EOA) of <0.8 cm2 or an indexed EOA of <0.5 cm2/m2 and a mean gradient of >40 mm Hg or peak velocity of >4 m/s. Patients with at least moderate stenosis and regurgitation were classified as having mixed bioprosthetic failure.
Patients were deemed to be at high risk if the heart team considered the risk of surgical mortality or major morbidity to be ≥50%. Key exclusion criteria were a bioprosthetic valve with a labeled size <21 mm, more than mild paravalvular regurgitation, left ventricular ejection fraction (LVEF) of <20%, or an estimated life expectancy of <2 years. The complete list of inclusion and exclusion criteria are shown in Online Table 1. All patients were presented to a Web-based conference call where imaging and clinical data were reviewed by a screening committee and approved. Transcatheter valve sizing was determined by expert consensus, manufacturers’ tables, and smartphone application-based sizing data (8,9). The trial was approved by the institutional review boards of all participating sites, and written, informed consent was provided by all patients.
The THV used was balloon expandable and consisted of bovine pericardial leaflets sutured to a cobalt chromium frame and a polyethylene terephthalate cuff that covered the lower portion of the frame. It was delivered through expandable 16-F (23-mm THV) or 18-F (26-mm THV) transfemoral delivery sheaths or by using transapical or transaortic access. Following the procedure, treatment with aspirin and clopidogrel for 6 months was recommended.
The trial was designed by members of the executive steering committee and the sponsor. The first author and coprincipal investigators had unrestricted access to the data. The sponsor had no role in data analysis or drafting of the manuscript.
Clinical assessments were performed at baseline and at all subsequent follow-up time points and included formal examination by a neurologist. Serial echocardiograms (intraprocedural, within 24 h of discharge and at 30 days) were analyzed independently by a core laboratory. A clinical events committee adjudicated all clinical events, and a data and safety monitoring board reviewed all adverse events.
The primary endpoint was all-cause mortality at 1 year. Nonpowered secondary endpoints included major vascular complications, stroke, acute kidney injury (according to Valve Academic Research Consortium-2 criteria), new permanent pacemaker insertion, myocardial infarction, and clinical improvements in symptoms, quality of life (QOL), Kansas City Cardiomyopathy Questionnaire (KCCQ) responses, and functional status (6-min walk test). Endpoints are defined in Online Table 2.
Data analysis of the valve implant population was conducted. Categorical variables were reported as percentages and compared using the chi-square or Fisher exact test, where appropriate. Continuous variables were reported as mean ± SD and compared using Student t test. Longitudinal data were modeled using a linear mixed model over the following time points: baseline, 30 days, and 1 year. The model included time as a fixed effect and assumed a compound symmetry covariance structure for observations within a patient. Results are presented as least squares means with 95% confidence intervals (CI). Cumulative incidence graphs and Kaplan-Meier estimates reflect time-to-event outcomes. Comparisons are based on the log-rank test results. A multivariate Cox proportional hazard regression model was used to assess the adjusted association between mortality and risk factors (Society of Thoracic Surgeons [STS] score, labeled valve size, THV size, mean gradient ≥20 mm Hg, and severe patient-prosthesis mismatch [PPM]). All statistical analyses were performed using SAS version 9.4 software (SAS Institute Inc., Cary, North Carolina).
Between June 2012 and December 2014, 367 patients were enrolled in both the initial registry and the continued access registry at 34 sites. Two patients did not undergo the procedure (1 withdrew consent, and the other was deemed inappropriate for the study valve), leaving 365 patients who underwent VIV procedures and are included in this analysis (96 in the initial registry, 269 in the continued access patients). At 1 year, no patients were lost to follow-up (Online Figure 1).
Patient and procedural characteristics
Mean age was 78.9 ± 10.2 years, and mean STS score was 9.1 ± 4.7%. The ages of the surgical bioprostheses were <5 years in 6.8%, 5 to 10 years in 26.8%, and >10 years in 66.3% of patients. Initial registry patients, compared to those in continued access, had similar STS scores but higher mean logistic EuroSCOREs (15.7 vs. 11.1, respectively; p = 0.002) and were more often frail (37.5% vs. 22.8%, respectively; p = 0.005), but no other significant differences were observed. Other baseline characteristics are shown in Table 1.
The labeled surgical valve sizes were <23 mm in 27.1%, 23 to 25 mm in 60.5%, and >25 mm in 12.4%. Pre-procedural computed tomography was performed in 90 patients (24.7%), and transesophageal echocardiography (either pre-procedural or intraprocedural) was performed in 351 patients (96.2%). Implanted THV sizes were 23 mm in 69% and 26 mm in 31%. The existing bioprostheses were stented in 92.3% of cases, stentless or a homograft in 6.0% of cases, and of unknown type in 1.6% of cases. The predominant failure modes were stenosis in 55.2%, regurgitation in 23.5%, and mixed in 21.3% of cases.
Transfemoral access was used in 75.4% (60.6% initial vs. 80.6% continued access; p = 0.0001). In the combined population of 365 patients, general anesthesia was used in 321 patients (87.9%). Post-dilation was performed in 37 of patients (10.1%). Valve embolization occurred in no patients, more than 1 THV was required in 7 patients (1.9%), coronary artery occlusion was required in 3 patients (0.8%), and conversion to open surgery was required in 2 patients (0.6%). Intra-aortic balloon pump counterpulsation and cardiopulmonary bypass were each required in 4 patients (1.1%). No patients died during the procedure. The median length of intensive care unit stay was 1 day (interquartile range [IQR]: 1 to 2 days), and the median length of hospital stay was 5 days (IQR: 3 to 8 days). Other procedural characteristics are shown in Table 2.
The rate of 30-day all-cause mortality was 2.7% (initial registry: 8.3%; continued access patients: 0.7%; p < 0.0001) and cardiovascular death was 2.5%. The rate of all stroke at 30 days was 2.7%, and disabling stroke was 2.2% (modified Rankin score: ≥2). Rehospitalization occurred in 5.9% of patients, major bleeding in 14.6%, major vascular complications in 4.1%, and a new permanent pacemaker was inserted in 1.9% of patients. Other clinical events are shown in Table 3. Significantly more major bleeding occurred in transapical than in transfemoral access patients (24.8% vs. 11.4%, respectively; p = 0.001), but no other significant differences in early outcomes were observed after comparing these cohorts.
Thirty-day echocardiographic evaluation was performed in 327 patients (90%; data not shown). From baseline to 30 days, mean EOA increased from 0.93 cm2 (95% CI: 0.89 to 0.98) to 1.13 cm2 (95% CI: 1.09 to 1.18), indexed EOA increased from 0.49 cm2/m2 (95% CI: 0.47 to 0.51) to 0.60 cm2/m2 (95% CI: 0.57 to 0.62), and mean gradient decreased from 35.0 mm Hg (95% CI: 33.7 to 36.2) to 17.7 mm Hg (16.5 to 19.0; all p < 0.0001).
Improvements in EOA (+0.33 cm2 vs. +0.06 cm2, respectively; p < 0.0001) and mean gradient (−21.7 mm Hg vs. −11.9 mm Hg; p < 0.0001) were more marked in patients with AS than in patients with aortic regurgitation (mixed or predominant). At 30 days, 96.8% had mild or less aortic regurgitation, and 3.2% had moderate or severe regurgitation (all paravalvular). No change in LVEF was seen between baseline and 30 days (50.6% vs. 50.1%, respectively; p = 0.52).
An elevated residual gradient (≥20 mm Hg) was observed on the first post-procedural echocardiogram in 34.3%, with no significant difference observed in comparison between the smallest 21-mm surgical valves and the larger valves (41.2% vs. 32.4%, respectively; p = 0.14). Severe PPM was defined as an indexed EOA of <0.65 cm2/m2 (or <0.60 for patients with a body mass index ≥30) (10). On the first post-procedural echocardiogram, severe PPM was present in 58.4% of patients. A significant difference was observed in comparison between 21-mm surgical valves and larger valves (69.4% vs. 55.0%, respectively; p = 0.0327). When stratified by labeled surgical valve size, however, all valve sizes showed an increase in EOA and a decrease in mean gradient from baseline to 30 days.
The true internal diameter (ID) of the surgical valve, as determined from published tables, was available in 258 of 365 patients (71%), with a true ID of ≤20 mm in 46.9%. This and the THV size were correlated with post-TAVR gradient on 30-day echocardiography and with PPM. Surgical valves with a true ID of <20 mm were strongly associated with post-TAVR mean gradient of >20 mm Hg and with severe PPM (p = 0.0042 and p < 0.0001, respectively), as was a THV size of <23 mm (p = 0.0003 and < 0.0001, respectively). Neither surgical valve true ID nor THV size, however, were predictive of 1-year mortality.
The 1-year overall Kaplan-Meier mortality estimate was 12.4%, and cardiac mortality was 9.0%. At 1 year, the rate of stroke was 4.5%, rehospitalization was 15.9%, and pacemaker insertion was 2.6%. Substantially lower mortality was observed in continued access patients than in those in the initial registry (9.8% vs. 19.8%, respectively; p = 0.006) (Figure 1). Increased mortality was seen in patients with an elevated (≥20 mm Hg) post-TAVR gradient (16.7% vs. 7.7%, respectively; p = 0.01). No increased mortality was observed in patients stratified according to mode of valve failure, access route, 21-mm surgical valves, or severe PPM (Figure 2), and multivariate analyses adjusted for these variables and baseline STS risk score revealed no significant associations with 1-year mortality.
One-year echocardiographic follow-up is shown in Table 4. At 1 year, the mean gradient was 17.6 mm Hg (95% CI: 16.2 to 19.1 mm Hg), EOA was 1.16 cm2 (95% CI: 1.11 to 1.21 cm2), and indexed EOA was 0.60 cm2/m2 (95% CI: 0.57 to 0.63 cm2/m2). When 30-day and 1-year echocardiographic data were compared, no significant differences in mean EOA (1.13 cm2 vs. 1.16 cm2, respectively; p = 0.30) or mean gradient (17.7 mm Hg vs. 17.6 mm Hg, respectively; p = 0.90) were seen (Figure 3). Patients with stenotic bioprosthetic failure had higher 1-year mean gradient (18.9 mm Hg vs. 16.0 mm Hg; p < 0.0001) and lower indexed EOA (0.57 vs. 0.65 cm2/m2; p < 0.0001) than those with regurgitant or mixed failure and had greater proportional changes in both mean gradient and EOA at 1 year. At 1 year, aortic regurgitation was none/trace in 93.2%, mild in 4.7%, and moderate or severe in 1.9%. No cases of more than mild aortic regurgitation were valvular (within the implanted THV) (Central Illustration).
Mean LVEF increased from 50.6% (95% CI: 49.0% to 52.1%) at baseline to 54.2% (95% CI: 52.3% to 56.1%) at 1 year (p < 0.0001). Overall, mean LV mass index decreased from 135.7 g/m2 (95% CI: 131.9 to 139.5 g/m2) at baseline to 125.4 g/m2 (95% CI: 121.6 to 129.8 g/m2) at 30 days and 117.6 g/m2 (95% CI: 113.3 to 121.8 g/m2) at 1 year (p < 0.0001 for trend). From baseline to 1 year, both the rate of moderate or severe mitral (34.9% vs. 12.7%, respectively; p < 0.0001) and tricuspid regurgitation (31.8% vs. 21.2%, respectively; p < 0.0001) decreased.
Symptoms and functional and QOL outcomes
Patient symptoms improved from baseline to 30 days and 1 year (Figure 4). The mean overall summary KCCQ score was 43.0 (least squares: 40.7 to 45.3) at baseline, increasing to 70.6 (68.2 to 72.9) at 30 days and 76.2 (73.5 to 78.8) at 1 year (p < 0.0001); and mean 6-min walk test distance increased from 163.7 m (least squares: 145.8 to 181.7) at baseline to 229.3 m (211.2 to 247.5 m) at 30 days and 248.0 m (226.9 to 269.1 m) at 1 year (p < 0.0001) (Central Illustration). No differences in KCCQ scores were seen when patients were stratified according to bioprosthesis size or residual gradient.
Results of the PARTNER 2 VIV registry showed that THV treatment of high-risk patients who had degeneration of surgical aortic bioprosthetic valves was associated with the following: low rates of mortality, stroke, rehospitalization, and new permanent pacemakers at 30 days and 1 year; significant reductions in transvalvular gradient and LV mass; significant increases in EOA and LVEF; very low rates of substantial aortic regurgitation; significant reductions in mitral and tricuspid valve regurgitation; and significant improvements in functional status and QOL (Central Illustration). These results are impressive considering the observed-to-expected mortality ratio was 0.3 at 30 days (observed mortality of 2.7% vs. STS predicted risk of surgical mortality of 9.1%).
In patients at high risk of complications from reoperation, the 1-year all-cause mortality of 12.4% was lower than the 16.8% rate reported in the retrospective nonadjudicated VIVID (Valve-in-Valve International Data) registry (7) and compared very favorably with earlier native valve PARTNER experiences using first-generation devices in similarly high-risk patients (PARTNER B mortality: 30.7%; PARTNER A mortality: 24.2%) (11,12). A learning curve for TAVR has been documented in the treatment of native valve stenosis but not in the context of VIV TAVR (13,14). A striking reduction in mortality from the initial registry to the continued access registry at 30 days (8.3% vs. 0.7%, respectively; p < 0.0001) and at 1 year (19.8% vs. 9.8%, respectively; p = 0.006) suggests a learning curve did exist. Important differences between native valve TAVR and VIV TAVR included much lower rates of paravalvular regurgitation (more than mild in only 1.9%), new pacemakers (1.9%), and annular rupture (0%). Presumably the rigid annular ring of the surgical bioprosthesis protected against these complications.
This is the first large VIV registry with core laboratory echocardiographic follow-up. A significant reduction in mean gradient and increase in valve area was durable to 1 year. Patients with severe AS benefited from a 0.33-cm2 increase in EOA and 21.7-mm Hg decrease in mean gradient, with residual aortic regurgitation less than mild in 98.1% of the entire cohort. At 1 year, however, an average residual mean gradient of 17.6 mm Hg remained, and criteria for severe PPM were met in 58.2.1% of VIV cases. Although residual gradient of ≥20 mm Hg was predictive of increased 1-year mortality, severe PPM was not. The impact of PPM on clinical outcomes following native valve SAVR and TAVR has been uncertain, with variable reports of its prognostic importance and some suggestions that any increase in mortality may only emerge very late after SAVR (15–23). To put this in perspective, in patients undergoing SAVR for native AS part of the PARTNER 2A intermediate-risk trial, 33% had severe PPM (24). Randomized studies have shown TAVR to have hemodynamics slightly superior to those in SAVR, with lower gradients and a lower prevalence of severe PPM (12,25–27). The higher gradients and higher rates of PPM after VIV procedures likely represent a combination of pre-existing PPM due to an undersized surgical valve and THV underexpansion due to the constraints of pre-existing surgical valves (7,26).
This is the first large VIV registry to systematically report functional and QOL outcomes after VIV TAVR. Even patients with PPM, small (21-mm) surgical valves, or elevated post-TAVR gradients showed marked improvements in symptoms, functional capacity, and QOL at 30-day and 1-year follow-up. In a highly comorbid population such as this, QOL measures take on great importance, perhaps even greater than mortality. PPM might have a less important impact on symptoms in elderly patients, which describes most VIV TAVR candidates (20).
The availability of VIV TAVR will likely influence surgical practice in the management of aortic valve disease, possibly lessening concerns about the durability of surgical bioprostheses. It is essential to realize, however, that specific characteristics of the chosen surgical bioprosthesis, (including its internal diameter, design characteristics, and proximity to the coronary ostia) will have an impact on whether a VIV procedure will or will not be a realistic future option. Unfortunately, current real-world data show that more than one-third of all patients undergoing SAVR receive a bioprosthesis smaller than 23 mm (1). Over the longer term, constrained THV expansion and malcoaptation within a bioprosthesis might lead to accelerated leaflet degeneration and reduced durability.
This investigation had a number of limitations, including the lack of a randomized comparator arm and follow-up limited to 1 year. The study was conducted in carefully selected sites with extensive oversight. The available THV sizes (23 and 26 mm) did not allow inclusion of patients with the largest or the smallest surgical bioprostheses. Clinical and hemodynamic outcomes may vary with different THV devices.
The use of VIV TAVR for the treatment of high-risk patients with degenerated aortic bioprostheses is associated with relatively low rates of mortality and major complications, improved hemodynamics and excellent improvement in functional and QOL outcomes at 1 year. Longer follow-up is required to determine the clinical importance of residual stenosis, particularly in smaller surgical valves, and the durability of transcatheter valves in this context.
COMPETENCY IN PATIENT CARE AND PROCEDURAL SKILLS: Transcatheter aortic valve replacement (TAVR) may be an alternative to cardiac reoperation in patients with degenerated aortic valve bioprostheses. In a large prospective registry of patients undergoing valve-in-valve TAVR, procedural and 1-year clinical, hemodynamic, functional, and QOL outcomes were generally favorable, but patient-prosthesis mismatch was relatively frequent.
TRANSLATIONAL OUTLOOK: Additional studies with longer follow-up are needed to determine the durability of transcatheter valves and clinical importance of patient-prosthesis mismatch in patients undergoing valve-in-valve TAVR.
For supplemental tables and a figure, please see the online version of this article.
The PARTNER (Placement of Aortic Transcatheter Valves) 2 trial was sponsored by Edwards Lifesciences. Dr. Webb is a consultant for Edwards Lifesciences, Abbott Vascular, and St. Jude Medical. Dr. Dvir is a consultant for Edwards Lifesciences. Dr. Herrmann has received grants from Edwards Lifesciences, St. Jude Medical, Medtronic, Boston Scientific, Abbott Vascular, Gore, Siemens, Cardiokinetix, and Mitraspan; is a consultant for Edwards Lifesciences and Siemens; and holds equity in Microinterventional Devices. Drs. Blanke and Leipsic are consultants for Edwards Lifesciences and provide uncompensated CT core lab services for Edwards Lifesciences, Medtronic, Neovasc, GDS, and Tendyne Holdings. Dr. Kodali has received grants from Edwards Lifesciences and Medtronic; and holds equity in Thubrikar Aortic Valve, Inc. Dr. Makkar has received grants from Edwards Lifesciences and St. Jude Medical; is a consultant for Abbott Vascular, Cordis, and Medtronic; and holds equity in Entourage Medical. Dr. Miller is supported by research grant R01 National Heart Lung Blood Institute HL67025; and has received consulting fees and honoraria from Abbott Vascular, St. Jude Medical, and Medtronic. Dr. Pibarot has uncompensated Core Lab contracts with Edwards Lifesciences and Medtronic. Dr. Pichard is a consultant for Edwards Lifesciences. Dr. Svensson holds equity in Cardiosolution and Valvexchange; and holds intellectual property with Postthorax. Ms. Alu is a consultant for Claret Medical. Dr. Suri is a member of the clinical steering committee at Abbott and St. Jude; is a consultant with Sorin and Abbott; and has a patent application with Sorin. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Abbreviations and Acronyms
- aortic stenosis
- effective orifice area
- Kansas City Cardiomyopathy Questionnaire
- left ventricular ejection fraction
- patient-prosthesis mismatch
- surgical aortic valve replacement
- transcatheter aortic valve replacement
- transcatheter heart valve
- Received December 19, 2016.
- Revision received February 28, 2017.
- Accepted February 28, 2017.
- 2017 American College of Cardiology Foundation
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