Author + information
- Received November 13, 2012
- Revision received February 14, 2013
- Accepted February 18, 2013
- Published online June 25, 2013.
- Rebecca T. Hahn, MD∗,†∗ (, )
- Philippe Pibarot, DVM, PhD‡,
- William J. Stewart, MD§,
- Neil J. Weissman, MD⋮,
- Deepika Gopalakrishnan, MD¶,
- Martin G. Keane, MD#,
- Saif Anwaruddin, MD#,
- Zuyue Wang, MD⋮,
- Martin Bilsker, MD∗∗,
- Brian R. Lindman, MD††,
- Howard C. Herrmann, MD#,
- Susheel K. Kodali, MD∗,†,
- Raj Makkar, MD‡‡,
- Vinod H. Thourani, MD§§,
- Lars G. Svensson, MD§,
- Jodi J. Akin, MS⋮⋮,
- William N. Anderson, PhD⋮⋮,
- Martin B. Leon, MD∗,† and
- Pamela S. Douglas, MD¶¶
- ∗NYP Columbia Heart Valve Center, Columbia University Medical Center, New York, New York
- †New York Presbyterian Hospital, New York, New York
- ‡Department of Medicine, Laval University, Quebec City, Quebec, Canada
- §Cleveland Clinic Foundation, Cleveland, Ohio
- ⋮Medstar Washington Hospital Center, Washington, DC
- ¶Medical City Dallas, Dallas, Texas
- #Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania
- ∗∗University of Miami, Miami, Florida
- ††Department of Medicine, Cardiovascular Division, Washington University in St. Louis School of Medicine, St. Louis, Missouri
- ‡‡Cedars-Sinai Medical Center, Los Angeles, California
- §§Emory University School of Medicine, Atlanta, Georgia
- ⋮⋮Edwards Lifesciences, Irvine, California
- ¶¶Division of Cardiovascular Medicine, Duke University Medical Center, Duke Clinical Research Institute, Durham, North Carolina
- ↵∗Reprint requests and correspondence:
Dr. Rebecca T. Hahn, Columbia University Medical Center, New York Presbyterian Hospital, 177 Fort Washington Avenue, New York, New York 10032.
Objectives This study sought to compare echocardiographic findings in patients with critical aortic stenosis following surgical aortic valve replacement (SAVR) or transcatheter aortic valve replacement (TAVR).
Background The PARTNER (Placement of Aortic Transcatheter Valves) trial randomized patients 1:1 to SAVR or TAVR.
Methods Echocardiograms were obtained at baseline, discharge, 30 days, 6 months, 1 year, and 2 years after the procedure and analyzed in a core laboratory. For the analysis of post-implantation variables, the first interpretable study (≤6 months) was used.
Results Both groups showed a decrease in aortic valve gradients and increase in effective orifice area (EOA) (p < 0.0001), which remained stable over 2 years. Compared with SAVR, TAVR resulted in larger indexed EOA (p = 0.038), less prosthesis-patient mismatch (p = 0.019), and more total and paravalvular aortic regurgitation (p < 0.0001). Baseline echocardiographic univariate predictors of death were lower peak transaortic gradient in TAVR patients, and low left ventricular diastolic volume, low stroke volume, and greater severity of mitral regurgitation in SAVR patients. Post-implantation echocardiographic univariate predictors of death were: larger left ventricular diastolic volume, left ventricular systolic volume and EOA, decreased ejection fraction, and greater aortic regurgitation in TAVR patients; and smaller left ventricular systolic and diastolic volumes, low stroke volume, smaller EOA, and prosthesis-patient mismatch in SAVR patients.
Conclusions Patients randomized to either SAVR or TAVR experience enduring, significant reductions in transaortic gradients and increase in EOA. Compared with SAVR, TAVR patients had higher indexed EOA, lower prosthesis-patient mismatch, and more aortic regurgitation. Univariate predictors of death for the TAVR and SAVR groups differed and might allow future refinement in patient selection. (THE PARTNER TRIAL: Placement of AoRTic TraNscathetER Valve Trial; NCT00530894)
- aortic stenosis
- surgical aortic valve replacement
- transcatheter aortic valve replacement
Transcatheter aortic valve replacement (TAVR) has emerged as a reasonable alternative to surgical aortic valve replacement (SAVR) (1–4). The PARTNER (Placement of Aortic Transcatheter Valves) trial was the first randomized trial comparing TAVR to standard-of-care therapies in a rigorous fashion. Two-year clinical outcomes in high-risk, operable patients with severe aortic stenosis (PARTNER Cohort A) showed TAVR was noninferior to SAVR without significant differences in all-cause mortality or cardiovascular mortality or evidence for structural valve failure.
Echocardiography is the recommended imaging modality for the assessment of aortic valve stenosis and prosthetic valve function (5–7) and was used for patient selection, valve sizing, and extended follow-up (1,2). In contrast to previous reports relying on site interpretations of images, the trial core laboratory provided rigorous quality control of the image acquisition and analysis process (8). The current investigation reports the complete, centrally analyzed echocardiographic findings from the high-risk, operable patient population (Cohort A).
Patient selection, study design, and management
Cohort A of the PARTNER trial (2) randomized 699 high-surgical-risk patients (mortality of ≥15%) with severe, symptomatic aortic stenosis, between SAVR and TAVR with the Edwards Sapien valve (Edwards Lifesciences, Irvine, California) (in a 1:1 ratio) (Fig. 1). All patients enrolled had site-determined, severe native tricuspid aortic stenosis defined by echocardiographically determined aortic valve area of ≤0.8 cm2 plus either a peak velocity ≥4 m/s or a mean gradient ≥40 mm Hg at rest or during dobutamine infusion. Study design and complete inclusion and exclusion criteria are presented in a previous publication (2).
Randomization to SAVR or TAVR was stratified by feasibility of transapical or transfemoral access. Echocardiograms were obtained at baseline, and at 7 days, 30 days, 6 months, 1 year, and 2 years after the procedure.
Echocardiography core laboratory analysis
All echocardiograms were analyzed at an independent core lab that followed the American Society of Echocardiography standards for echocardiography core laboratories (9). Image acquisition quality was ensured by use of a detailed acquisition protocol, site qualification and training with quality feedback at regular intervals, and retraining of sites with unacceptable image quality. Image analysis quality was ensured by reader qualification, detailed analysis instructions, group and individual training, regular intra- and interobserver variability testing, retraining, and coaching when indicated (9). All measurements and analyses were performed without knowledge of clinical or other laboratory data including previous echocardiography results, group assignment, and timing of the assessment.
Reproducibility was determined on 649 to 1,360 pairwise comparisons among readers for each of 8 critical variables on 30 echocardiograms (total number of comparisons = 8,031). Intraclass correlation coefficients were 0.92 to 0.99 for physician over-readers and 0.89 to 0.97 for sonographers. Kappa statistics for agreement for categorical variables calculated for physician over-readers were 0.56 to 0.85.
Ventricular size and function and valvular function were measured according to previously published guidelines (6,7,10). An integrative, semiquantitative approach was used to assess the severity of valvular regurgitation. Both qualitative (visual) and quantitative (biplane Simpson method of disks) approaches were used to report ejection fraction. Relative wall thickness (RWT) was calculated as 2× posterior wall thickness/left ventricular end-diastolic dimensions (LVED) (RWTp) and also using the posterior wall thickness plus septal wall thickness as (septal wall thickness + posterior wall thickness)/LVED, or RWTm. Site-reported systolic annulus diameters were derived from long-axis views. The effective orifice area (EOA) is calculated as the Doppler stroke volume/aortic velocity time integral. The cover index was determined as (11): [prosthesis diameter – annular diameter]/prosthesis diameter. The severity of prosthesis-patient mismatch was graded using EOA indexed to body surface area (6) with absence defined as >0.85 cm2/m2, moderate ≥0.65 and ≤0.85 cm2/m2, and <0.65 cm2/m2.
Paravalvular regurgitation after TAVR/SAVR was graded in accordance with the ASE recommendations for native valves (12) and adoption of the 2009 prosthetic valve guidelines (6) with the following exception. Because of the eccentric, irregular, jet and the frequent noncylindrical “spray” of the paravalvular jet contour, the parasternal short-axis view(s) was weighted more heavily than other signals in providing an integrated assessment, as follows: none = no regurgitant color flow; trace = pinpoint jet in aortic valve; mild = jet arc length is <10% of the annulus circumference; moderate = jet arc length is 10% to 30% of the annulus circumference; severe = jet arc length is >30% of the annulus circumference.
Analysis is based on the actual valve implant patients who received and retained either a surgical or transcatheter valve, as this group is most appropriate for studying the echocardiographic measurements and outcomes. Intention-to-treat analysis (ITT) for evaluating trial endpoints has previously been reported (2,4). Because of the difficulty in imaging patients immediately following intervention, the first post-implantation values are obtained from the first available value at discharge, 30 days, or 6 months.
Categorical variables were compared using Fisher exact test. Because regurgitation and prosthesis-patient mismatch are ordinal variables, comparisons involving these variables use the exact Jonckheere-Terpstra test. It should be noted that when 1 of the variables has 2 levels, the test is equivalent to the exact Mann-Whitney U test; where both have >2 levels, the use of the Jonckheere-Terpstra test is important. Continuous variables were presented as mean ± SD and were compared using Student t test; comparisons with baseline values use the paired sample Student t test. Survival curves for time-to-event variables were constructed using Kaplan-Meier estimates based on all available data and were compared using the log-rank test. To study the impact of risk factors on mortality, Cox proportional hazards regression was performed.
Imputation was not performed for missing baseline or first post-implantation variables except in the multivariable models. The effect is that patients whose values are missing for a particular analysis are removed from that analysis.
Data are based on an extract date of February 13, 2012. All statistical analyses were performed in SAS software (version 9.2, SAS Institute, Cary, North Carolina).
In the ITT TAVR arm, there were 348 randomized patients; 344 were as-treated TAVR and 326 were valve implantations of which 97 used transapical and 229 used transfemoral approaches. In the ITT SAVR arm, there were 351 randomized patients; of these 313 were as-treated SAVR and 310 were valve implantations (Fig. 1). Patients' baseline clinical demographics using the ITT populations are listed in Online Table 1. There were no statistically significant differences between the groups, except there were more patients with high creatinine in the TAVR group.
Baseline echocardiographic parameters
There were no baseline differences in left ventricular (LV) size, geometry, and function between as-treated SAVR and TAVR groups (Online Table 2). The 2 groups were similar in LVED, left ventricular end-systolic dimensions (LVES), RWTp and RWTm, left ventricular mass, left ventricular mass index, left ventricular diastolic volume (LVDV), left ventricular systolic volume (LVSV), and LV stroke volume as well as calculated ejection fraction.
Baseline valvular hemodynamics have previously been reported (4) and are summarized in Online Table 2. There were no significant differences between SAVR and TAVR groups for baseline peak velocity, peak gradient, mean gradient, stroke volume–calculated (by any method) aortic valve area, or aortic valve area index. There was no significant difference in the severity of mitral or aortic regurgitation.
Ventricular and valvular changes immediately following intervention
In the TAVR cohort (Online Table 3), neither LVED nor LVDV changed immediately after intervention; however, LVES (p = 0.0005) and LVSV (p = 0.0016) were significantly smaller and ejection fraction was higher (p < 0.0001). Peak and mean aortic valve gradients decreased (p < 0.0001) and EOA increased (p < 0.0001). There was a significant reduction in mitral regurgitation (p < 0.0001) with no change in total aortic regurgitation (p = 0.649).
In the SAVR cohort there was a significant decrease in LVED, LVDV, LVES, and LVSV immediately following intervention (Online Table 3), associated with reduced stroke volume by 2-dimensional echocardiography (p < 0.0001) and Doppler echocardiography (p < 0.0001), but no change in ejection fraction. Peak and mean aortic valve gradients decreased (p < 0.0001) with an increase in EOA (p < 0.0001). There was a significant reduction in both mitral regurgitation and aortic regurgitation (p < 0.0001).
Comparison of SAVR and TAVR
Online Table 4 compares TAVR and SAVR baseline and post-implantation echocardiographic variables of ventricular size and function. TAVR as compared to SAVR had a significantly larger LVED up to 6 months following valve replacement, but not after 1 or 2 years of follow-up. LVDV showed inconsistent differences, neither LVES nor LVSV showed between-group differences throughout follow-up. LV mass and LV mass index were larger in the TAVR patients at discharge, 6 months, and 1 year, but not at 2 years. The percentage of LV mass reduction was initially greater for the SAVR group, but was not significantly different after 6 months. RWTp and RWTm following valve replacement were initially higher for the SAVR group but progressively decreased for both groups.
Although 2-dimensional echocardiography stroke volume showed inconsistent differences at various times, Doppler stroke volume was significantly larger in TAVR patients up to 2 years, at which time there was no significant difference. There was no significant between-group difference in ejection fraction throughout follow-up.
Online Table 5 compares the baseline and post-implantation echocardiographic variables of valvular function, for TAVR versus SAVR groups. Peak and mean transaortic gradients were significantly lower in the TAVR group for most follow-up times. EOA and indexed EOA were significantly larger in TAVR at all follow-up times. Prosthesis-patient mismatch was more common in the SAVR group throughout follow-up (Fig. 2, Online Table 6). There were no significant differences in mitral regurgitation between TAVR and SAVR groups up to 2 years (Fig. 3, Online Table 5).
TAVR patients had significantly more total aortic regurgitation at every post-implantation time than did patients in the SAVR cohort (Online Tables 5 and 7). Mild, moderate, or severe paravalvular aortic regurgitation (Fig. 4, Online Table 8) was more common in the TAVR group at every follow-up time (p < 0.0001).
There were no cases of structural valve failure or migration of the valve after initially successful implantation in either group.
Within-group changes over time
Online Tables 4 and 5 show within-group changes over the 2-year follow-up period. Both groups showed a continuous reduction in RWT and LV mass or LV mass index over time. After an initial fall in Doppler stroke volume in the SAVR group, both groups showed significant increases in stroke volume over time. The TAVR group showed an immediate increase in ejection fraction following intervention with no change up to 2 years. The SAVR group showed no immediate increase in ejection fraction but a significant increase at 2 years. Both groups showed immediate reduction in peak and mean transaortic gradients with slight further reductions over time. Both groups showed a sustained, stable increase in EOA and indexed EOA.
Following intervention, there was no significant change in total aortic regurgitation in the TAVR group, and an immediate reduction in the SAVR group followed by a slight increase in aortic regurgitation over time (Online Table 5). Mitral regurgitation severity was reduced in both groups following intervention but showed a slight increase from immediate post-intervention levels by 2 years.
In the TAVR group, paravalvular aortic regurgitation remained unchanged in 45.4% of patients, improved in 31.9%, and worsened in 22.7% of patients. Seven patients worsened from none/trace/mild to moderate following intervention. Conversely, 8 patients improved from moderate to none/trace/mild. No patient developed new severe aortic regurgitation. There was no significant baseline patient clinical differences between patients with none/trace or ≥mild paravalvular aortic regurgitation (Online Table 9); however, there were significant differences in echocardiographic measures of ventricular size and function. Patients with ≥mild paravalvular aortic regurgitation had larger baseline measurements of aortic annular dimensions (p = 0.040), LVED (p =0.008), LVDV (p = 0.019), LV mass (p = 0.003), and LV mass index (p = 0.007). Baseline ejection fraction was also lower in the ≥mild paravalvular aortic regurgitation group. A greater number of patients with ≥mild paravalvular aortic regurgitation had low stroke volume (≤35 ml/m2) at baseline. There were no significant differences in baseline gradients or valve area. There was no impact of the prosthesis size on severity of total aortic regurgitation (none, trace, mild, moderate, or severe) (p = 0.38, not shown) or paravalvular aortic regurgitation following TAVR (Online Table 9).
Following TAVR, patients with ≥mild paravalvular aortic regurgitation had larger values for first post-implantation LVED (p = 0.009), LVDV (p = 0.003), LV mass (p = 0.001), and LV mass index (p = 0.007). There was no difference in first post-implantation ejection fraction, transaortic gradients, EOA, prosthesis-patient mismatch, or implanted valve size. There was a higher frequency of low cover index (<8%) in patients with ≥mild paravalvular aortic regurgitation (p = 0.012). There was a significantly higher 2-dimensional echocardiography and Doppler stroke volume in the ≥mild paravalvular aortic regurgitation group.
Echocardiographic variables associated with outcome
Univariate echocardiographic determinants of mortality in the TAVR group were evaluated (Online Table 10). The only baseline echocardiographic univariate predictor of death in the TAVR group was baseline peak gradient (hazard ratio [HR]: 0.94, 95% confidence interval [CI]: 0.90 to 0.99, per 5 mm Hg increase, p = 0.010). After implantation, there were a number of echocardiographic univariate predictors of death in the TAVR group, the strongest of which was ≥mild paravalvular aortic regurgitation (HR: 2.11, 95% CI: 1.43 to 3.10, p = 0.0002). Other post-TAVR predictors of mortality include larger LVDV, LVSV and indexed EOA, and lower ejection fraction. The presence of prosthesis-patient mismatch (indexed EOA <0.85 cm2/m2) was a predictor of decreased mortality (HR: 0.736, 95% CI: 0.57 to 0.96, p = 0.024).
There were many baseline univariate echocardiographic determinants of mortality in the SAVR group (Online Table 11), the strongest of which was mitral regurgitation (HR: 1.49, 95% CI: 1.17 to 1.90, per 1 grade, p = 0.001). After valve replacement, the strongest univariate echocardiographic predictors of death were the presence of low stroke volume (≤35 ml/m2) (HR: 1.97, 95% CI: 1.16 to 3.33, p = 0012) and prosthesis-patient mismatch (HR: 1.43, 95% CI: 1.11 to 1.84, p = 0.005). Other post-SAVR predictors of mortality include smaller LVDV, LVSV, EOA, and stroke volume.
Cohort A of the PARTNER trial is the first large randomized trial showing comparable outcomes of SAVR and TAVR in high-risk, operable patients with severe symptomatic aortic stenosis (4). The present study reports the centrally analyzed echocardiographic data comparing SAVR and TAVR, which document early and sustained hemodynamic improvements with both therapies, and freedom from structural valve deterioration, while highlighting the differences in therapeutic groups, and presenting echocardiographic determinants of outcome.
Improvements in valve area and mean gradients are sustained over the 2-year interval reported with no evidence of stent recoil in the TAVR group. No structural valve dysfunction was found out to 2 years in either arm of this study. The current study thus highlights the 2-year durability of the Edwards Sapien balloon-expandable valve.
Ventricular remodeling and function
Following valve replacement, there is substantial ventricular remodeling with reduction in RWT and LV mass in both groups. The SAVR group had more absolute LV mass regression early; however, there was no difference in mass regression rates over the follow-up period between SAVR and TAVR. Factors other than valve area may adversely influence LV remodeling including more aortic regurgitation (in the TAVR population) or concomitant surgical procedures (mitral valve repair/replacement or coronary bypass performed as protocol violations in the SAVR population).
Ejection fraction improves early following TAVR and later during follow-up in the SAVR group with no significant difference by 2 years. Because LVED, LVES, and mitral regurgitation are not significantly different between groups, the larger stroke volumes in the TAVR group support the qualitative finding of greater aortic regurgitation. Other factors that could influence LV remodeling (i.e., hypertension, renal dysfunction, sex) and ventricular function warrant further study.
Factors associated with outcome
The TAVR and SAVR groups had different univariate factors associated with outcome. In the TAVR group, only baseline low peak gradients, possibly in the setting of low stroke volume, predicted worse outcome. Post-TAVR, larger LV volumes (either systolic or diastolic) and lower ejection fractions determined worse outcome; how this may be related to aortic regurgitation is unknown. In the SAVR group, baseline or post-SAVR small LVED volume and low stroke volume are associated with increased mortality. The strongest predictor of mortality was baseline severity of mitral regurgitation. Six patients had concomitant mitral surgery (a protocol violation), and how this might influence outcomes requires further investigation.
Similar to previous studies (13), our study confirms that prosthesis-patient mismatch has a negative effect on survival in the SAVR population. Also similar to prior studies (14), indexed EOA in the TAVR groups is larger than it is in the SAVR group despite comparable annular dimensions. Counterintuitively, univariate analysis of the TAVR group had a lower mortality in the presence of prosthesis-patient mismatch. This finding might be driven by body size, because in the TAVR cohort, body mass index was also associated with lower mortality (Online Table 10). Conversely, this finding may also be driven by a population of patients with a small annulus; patients with a small aortic annulus have better outcomes with TAVR than with SAVR (15,16). In addition, a small annulus in the TAVR population has been associated with less paravalvular aortic regurgitation (11). Further multivariable modeling should be performed.
Recent surgical studies suggest paravalvular regurgitation following SAVR occurs in 10% to 48% of patients (17–22) and even mild paravalvular regurgitation has a negative impact on survival (23). The current study confirms a high incidence of aortic regurgitation in the SAVR group (50%); however, only 14% have ≥mild paravalvular aortic regurgitation.
Our study supports other studies (13,24–26) showing a significant relationship between mortality and paravalvular aortic regurgitation in TAVR patients. Despite the inherent limitations of the current grading method for paravalvular regurgitation, it has been shown to predict outcomes (4), which provides indirect validation. Further validation of this grading scheme against other quantitative assessments of severity of regurgitation should be performed. Finally, differences in the baseline characteristics between groups with paravalvular aortic regurgitation might have contributed to the increased mortality.
We used the site-specified systolic annular measurement because: 1) most were from intraprocedural transesophageal echocardiograms and likely more accurate than transthoracic measurements; and 2) the measurement was performed in systole (whereas as per previously published guidelines (10), the echocardiographic core laboratory performed aorta measurements in diastole). In the PARTNER trial, a systolic, sagittal plane systolic annulus was used for sizing the transcatheter heart valve.
Whenever possible, we evaluated paired echocardiographic data; however, longitudinal differences between groups with high mortality rates may introduce survivorship bias. Finally, echocardiographic measurements are dependent on image quality as well as inter- and intraobserver variability. Use of an echocardiographic core laboratory should limit this variability as has been demonstrated previously for the PARTNER trial (8); however, limited echocardiographic measurability may introduce another form of bias. In addition, several variable comparisons have been made in the manuscript, and no adjustment has been made for the multiple comparisons.
For the “first post-implantation” measurement, discharge or 30-day values were used in 90% to 96% of ventricular size and function measurements, and 99% of Doppler measurements; 6 month data were rarely used.
The limitations of paravalvular aortic regurgitation grading have been discussed but remain a significant issue for both surgical and transcatheter valves. It is important to note that the circumferential extent grading scheme used differs slightly from the upper cut point of 20% for moderate paravalvular regurgitation recommended by the 2009 American Society of Echocardiography/European Association of Echocardiography guidelines (6), which were published after the PARTNER analysis plan was established.
Advanced echocardiographic techniques, such as 3-dimensional color Doppler echocardiography or quantitative methods, as well as intraprocedural studies were not evaluated.
This study is the first to use centrally analyzed echocardiographic data to compare the structural and hemodynamic results in high-risk patients with symptomatic severe aortic stenosis randomized to SAVR or TAVR. Immediately following valve replacement, both groups showed a significant reduction in transaortic gradients and an increase in EOA with similar LV mass regression and remodeling over time. However, indexed EOA was consistently higher and prosthesis-patient mismatch lower in the TAVR group throughout the follow-up period. The intermediate-term durability of the Edwards Sapien valve is comparable to SAVR. Survival was strongly affected by low stroke volume and prosthesis-patient mismatch in the SAVR cohort and post-intervention aortic regurgitation in the TAVR cohort. A complete understanding of these differences may allow future refinement in patient selection.
Dr. Pibarot has received an unrestricted research grant from Edwards Lifesciences. Dr. Anwaruddin is a coinvestigator on the PARTNER 2 trial. Dr. Herrmann is supported by a research grant awarded to his institution from Edwards Lifesciences; has received consulting fees from St. Jude Medical and Paieon; and holds equity in Microinterventional Devices. Dr. Kodali has received consulting fees from Edwards Lifesciences and Medtronic; and is a member of the Scientific Advisory Boards of Thubrikar Aortic Valve, Inc., the Medical Advisory Board of Paieon Medical, and the TAVI Steering Committee of St. Jude Medical. Dr. Thourani has received research support from Edwards Lifesciences; and consulting fees from Edwards Lifesciences, Sorin Medical, St. Jude Medical, and DirectFlow. Dr. Svensson has received travel reimbursement from Edwards Lifesciences for activities related to his participation on the Executive Committee of the PARTNER Trial. Ms. Akin is a salaried employee of Edwards Lifesciences. Dr. Anderson is a consultant for Edwards Lifesciences; he also owns stock in Edwards Lifesciences. Dr. Leon has received travel reimbursement from Edwards Lifesciences for activities related to his participation on the Executive Committee of the PARTNER Trial. Dr. Douglas has received institutional research support from Edwards Lifesciences. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Abbreviations and Acronyms
- confidence interval(s)
- effective orifice area
- hazard ratio(s)
- intention-to-treat analysis
- left ventricular
- left ventricular diastolic volume
- left ventricular end-diastolic dimensions
- left ventricular end-systolic dimensions
- left ventricular systolic volume
- relative wall thickness
- relative wall thickness: the septal and posterior wall thickness
- relative wall thickness: using formula twice the posterior wall thickness
- surgical aortic valve replacement
- transcatheter aortic valve replacement
- Received November 13, 2012.
- Revision received February 14, 2013.
- Accepted February 18, 2013.
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