Highlights
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Echocardiography systematically overestimates post-TAVR gradients compared with invasive measurements, particularly with balloon-expandable valves.
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Gradient discrepancy (Echo-Invasive) was not linked to increased 30-day or 1-year mortality.
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Female sex, hypertension, preserved left ventricular function, small valve size, and small aortic annulus were associated with greater gradient differences.
Abstract
Background
Transcatheter aortic valve replacement (TAVR) is a key treatment for severe aortic stenosis (AS). Several studies have consistently shown discrepancies between transvalvular gradients measured by transthoracic echocardiography (TTE) and those obtained invasively. The aim of this study was to evaluate this discrepancy in a large patient cohort and determine whether it is associated with clinical outcomes.
Methods
This study included patients with severe AS who underwent TAVR using either balloon-expandable (BEVs) or self-expanding valves (SEVs). The primary endpoint was the magnitude of discrepancy between peak transvalvular gradients measured by TTE and invasive hemodynamic assessment. Secondary endpoints included the association of this gradient difference with in-hospital, 30-day, and 1-year mortality. In addition, multivariable linear regression analysis was performed to identify independent predictors of gradient discrepancy.
Results
A total of 1,798 TAVR patients were included: 799 received BEVs and 999 received SEVs. Postprocedural mean peak gradients by echocardiography were significantly higher in the BEV group (20 ± 8 mmHg) than in the SEV group (15 ± 7 mmHg; P <.001). Invasive mean peak gradients were lower overall, at 5.9 ± 4 mmHg for BEVs and 5.3 ± 3.8 mmHg for SEVs ( P =.001). The mean difference between echocardiographic and invasive measurements was significantly greater in the BEV group (14 ± 8 mmHg) compared to the SEV group (10 ± 7 mmHg; P <.001). There were no statistically significant differences in mortality between the BEV and SEV groups. Additionally, female sex, hypertension, preserved left ventricular function, small valve size, and small aortic annulus were all linked to greater differences between echocardiographic and invasive gradients.
Conclusion
echocardiographic gradients after TAVR consistently overestimate invasive values, especially with balloon-expandable valves, but without impacting short or mid-term mortality.
Background
Transcatheter aortic valve replacement (TAVR) has become an established treatment for patients with severe aortic stenosis (AS). Current guidelines recommend TAVR as a first-line therapy in patients aged 70 years or older when anatomically feasible, and it is increasingly used across the full spectrum of surgical risk. ,,, Following TAVR, the assessment of residual transvalvular gradients is routinely performed to evaluate prosthetic valve function. This is typically done using transthoracic echocardiography (TTE), but in many cases, invasive hemodynamic measurements are also obtained at the end of the procedure. Several studies in recent years have identified a consistent discrepancy between the transvalvular gradients measured by TTE and those measured invasively, particularly in patients who received balloon-expandable valves (BEVs). ,,, In most of these cases, echocardiographic gradients appear to be higher than those obtained via direct catheter-based measurement. This has raised questions regarding the accuracy and prognostic significance of each modality. Importantly, existing evidence suggests that this gradient discrepancy is not associated with adverse clinical outcomes, including short-term mortality However, most of the published studies to date have involved relatively small cohorts, limiting the generalizability of their findings.
The aim of this study was to evaluate the discrepancy between postprocedural peak transvalvular gradients measured by TTE and invasive hemodynamic assessment in a large cohort of patients undergoing TAVR, and to assess whether this difference is associated with clinical outcomes.
Methods
Study population
This retrospective, single-center clinical registry was conducted at Clinique Pasteur (Toulouse, France). Data were collected from all patients undergoing TAVR for severe aortic stenosis using balloon (Edwards Sapien 3, Sapien 3 Ultra, Colibri, and MyVal) or self-expandable (Medtronic Evolut R, Evolut Pro, Evolut Pro+, Navitor, and ACURATE neo) valves (SEVs) between 2013 and 2024. Patient selection for TAVI followed the European Society of Cardiology guidelines for valvular heart disease and was determined by a multidisciplinary Heart Team. All patients provided informed consent for the use of their medical records for research purposes.
The primary endpoint of this study was to measure the magnitude of discrepancy between peak transvalvular gradients measured by transthoracic echocardiography and invasive hemodynamic assessment after TAVR with BEVs and SEVs. Invasive transvalvular gradients were obtained using simultaneous left ventricular and aortic pressure recordings, allowing direct peak-to-peak gradient measurement without catheter pullback. Pressure recordings were obtained at the end of the procedure under stable hemodynamic conditions before sheath removal. Echocardiographic gradients were obtained prior to hospital discharge, typically within the first day after the intervention. It is important to clarify that the aim of this study was to evaluate post-TAVR hemodynamic discrepancy rather than stenosis severity. Accordingly, peak Doppler gradients were compared with invasive peak gradients, as both capture maximal transvalvular pressure differences. Secondary endpoints included evaluating whether this difference in gradients was linked to in hospital, 30-day mortality and 1-year mortality, as well as periprocedural stroke rates between BEV and SEV groups. Additionally, the study examined how the gradient discrepancy varied across different patient subgroups and a multivariable linear regression analysis was performed to identify independent predictors of gradient discrepancy, with the difference between echocardiographic and invasive peak gradients used as the dependent variable. Furthermore, given concerns regarding long-term outcomes associated with the ACURATE Neo valve unrelated to transvalvular gradients, a predefined sensitivity analysis was performed evaluating this subgroup separately before inclusion in the primary analysis.
Statistical analysis
Continuous variables are presented as mean ± standard deviation (SD), and categorical variables as counts and percentages. Differences between echocardiographic and invasive peak gradients were assessed using paired t-tests. For each patient, the mean difference (∆Gradient = Echo–Invasive) was calculated and analyzed across the cohort. Agreement between modalities and potential systematic bias were evaluated using Bland–Altman analysis. Correlation between the 2 measurements was assessed with Pearson’s correlation coefficient and illustrated via scatterplot. We compared in-hospital, 30-day, and 1-year mortality rates between patients with a ∆Gradient ≥ 10 mmHg and those with smaller differences, using Fisher’s exact test or chi-square test as appropriate. Subgroup analyses were conducted to explore whether SEV type, sex, hypertension, left ventricular ejection fraction (LVEF), aortic annulus size, or valve size influenced the magnitude of gradient differences. All analyses were performed using SPSS statistical software, version 29.0.2.0 (IBM Corp., Armonk, NY). A 2-tailed P -value <.05 was considered statistically significant.
Results
Baseline characteristics
Of an initial 7,000 patients who underwent TAVR, only 1,798 were included in the analysis after excluding those with missing paired invasive and postprocedural echocardiographic gradient measurements or missing 30-day or 1-year follow-up data (baseline characteristics of included and excluded patients are shown in Supplementary Table 1); comprising 799 treated with BEVs and 999 with SEVs. Table 1 summarizes the baseline characteristics of the study population. The mean age was 82 years in the BEV group and 83 years in the SEV group. The BEV group included a higher proportion of males compared to the SEV group (69% vs 45%). Coronary artery disease was more prevalent in the SEV group (37% vs 22%), while peripheral vascular disease was more common in the BEV group (15% vs 9%). Left ventricular ejection fraction (LVEF) at baseline was 56% in the BEV group and 60% in the SEV group. The mean aortic valve area (AVA) was 0.81 cm² in the BEV group and 0.78 cm² in the SEV group, with mean aortic gradients of 46 mmHg and 48 mmHg, respectively. The mean Society of Thoracic Surgeons (STS) score and EuroSCORE were slightly higher in the BEV group (5.0 and 4.8) than in the SEV group (4.4 and 4.4).
Table 1
Baseline characteristics
| Characteristic | BEVs ( n = 799) | SEVs ( n = 999) | P -value |
|---|---|---|---|
| Age, years (mean ± SD) | 82 ± 6 | 83 ± 6 | .2 |
| Gender, male n (%) | 554 (69) | 449 (45) | <.001 |
| Cardiovascular comorbidities | |||
| Dyslipidemia, n (%) | 364 (45) | 405 (40) | .03 |
| Hypertension, n (%) | 621 (77) | 750 (75) | .1 |
| Diabetes mellitus, n (%) | 186 (23) | 242 (24) | .6 |
| Coronary artery disease, n (%) | 178 (22) | 378 (37) | <.001 |
| Prior PCI, n (%) | 265 (33) | 250 (25) | <.001 |
| Prior CABG, n (%) | 61 (7) | 58 (6) | .1 |
| Prior CVA/TIA, n (%) | 72 (9) | 83 (8) | .5 |
| PVD, n (%) | 123 (15) | 94 (9) | <.001 |
| Baseline TTE data | |||
| LVEF%, (mean ± SD) | 56 ± 12 | 60 ± 10 | <.001 |
| NYHA class I-II, n (%) | 536 (67) | 715 (72) | .03 |
| NYHA class III-IV, n (%) | 263 (33) | 284 (28) | .04 |
| AVA, cm² (mean ± SD) | 0.81 ± 0.2 | 0.78 ± 0.2 | .1 |
| AVA index, (mean ± SD) | 0.44 ± 0.13 | 0.45 ± 0.12 | .1 |
| Mean aortic gradient, mmHg, (mean ± SD) | 46 ± 13 | 48 ± 13 | .004 |
| Surgical risk | |||
| Euroscore II, (mean ± SD) | 5 ± 4 | 4.4 ± 4 | .01 |
| STS score, (mean ± SD) | 4.8 ± 3 | 4.4 ± 3.5 | .007 |
AVA, aortic valve area; CABG, coronary artery bypass graft; CVA, cerebrovascular accident; LVEF, left ventricle ejection fraction; PCI, percutaneous coronary intervention; PVD, peripheral vascular disease; TIA, transient ischemic attack.
Procedural details and postprocedural outcomes
Table 2 summarizes the procedural details and postprocedural outcomes. The majority of implanted valves were larger than 23 mm, accounting for 78% in the BEV group and 92% in the SEV group. The average procedure duration was similar between groups, at 50 minutes for BEV and 48 minutes for SEV. postprocedural doppler mean gradients were significantly higher in the BEV group compared with the SEV group (12 ± 4 vs 9 ± 4 mmHg, P <.001). postprocedural mean peak gradients measured by echocardiography were also significantly higher in the BEV group (20 ± 8 mmHg) compared to the SEV group (15 ± 7 mmHg; P <.001). Invasive mean peak gradients were lower overall, measuring 5.9 ± 4 mmHg in BEV and 5.3 ± 3.8 mmHg in SEV ( P =.001). The average difference between echocardiographic and invasive measurements was greater in the BEV group (14 ± 8 mmHg) than in the SEV group (10 ± 7 mmHg; P <.001). Figures 1 A and B display scatterplots illustrating the relationship between invasive and echocardiographic peak gradients. Correlation was very weak in both groups (BEV: r = 0.03; SEV: r = 0.06), indicating poor linear agreement between the 2 measurement methods. Moreover, most points lie above the line of identity, consistent with higher values obtained by echocardiography. Bland–Altman plots analysis ( Figures 2 A and B) demonstrated a positive mean bias, indicating systematically higher gradients measured by echocardiography compared with invasive assessment. In both valve groups, the dispersion of differences widened at higher average gradients. Regression of the difference versus the mean confirmed proportional bias, with the discrepancy increasing as gradient magnitude rose (BEV slope β = 0.99; SEV slope β = 1.03).
Table 2
Procedural and post-procedural data
| Characteristic | BEVs ( n = 799) | SEVs ( n = 999) | P -value |
|---|---|---|---|
| Valve size | |||
| ≤23mm, n (%) | 175 (22) | 79 (8) | <.001 |
| >23mm, n (%) | 624 (78) | 920 (92) | <.001 |
| Procedure duration, minutes (mean ± SD) | 50 ± 24 | 48 ± 20 | .02 |
| Contrast volume, ml (mean ± SD) | 80 ± 39 | 87 ± 37 | <.001 |
| Fluoroscopy time, minutes (mean ± SD) | 12 ± 6 | 12 ± 6 | .6 |
| Echo mean gradient post-TAVR, (mean ± SD) | 12 ± 4 | 9 ± 4 | <.001 |
| Echo peak gradient post-TAVR, (mean ± SD) | 20 ± 8 | 15 ± 7 | <.001 |
| Invasive peak gradient post-TAVR, (mean ± SD) | 5.9 ± 4 | 5.3 ± 3.8 | .001 |
| Δ = Echo–invasive, (mean ± SD) | 14 ± 8 | 10 ± 7 | <.001 |
| In hospital mortality, n (%) | 6 (0.75) | 7 (0.7) | .901 |
| 30-day mortality, n (%) | 9 (1.1) | 14 (1.4) | .606 |
| 1-year mortality, n (%) | 63 (7.8) | 58 (5.8) | .080 |
| Peri-procedural stroke, n (%) | 8 (1) | 9 (0.9) | .982 |
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