Effect of pressure recovery on invasive-echocardiographic gradient discordance after TAVR

Background. Echocardiographic evaluation is the standard of care for assessing transcatheter heart valve (THV) performance. However, this method frequently overestimates invasive trans-valvular gradients. In bench studies, this discrepancy has been attributed to pressure recovery (PR), particularly in patients with small aortic root dimensions and those treated with balloon-expandable valves (BEVs). Objectives. To investigate in vivo whether adjustment of echocardiographic gradients for PR reduces the discordance between invasive and non-invasive hemodynamic evaluation in different THV types. Methods. In this single-center prospective registry, 126 patients (median age 81 years; STS-PROM 4.0%) undergoing transfemoral transcatheter aortic valve replacement (TAVR) with contemporary BEV (n=54) or self-expanding (SEV, n=72) THVs were evaluated. Post-procedural echocardiographic mean gradients (echoMG) and PR-adjusted gradients (PRadjMG) were compared with invasive mean gradients (invMG). PR correction was performed using ascending aortic cross-sectional area (AA) derived from transthoracic echocardiography or computed tomography (CT). Results. In the overall cohort, echoMG systematically overestimated invMG (9 vs 5 mmHg, p<0.001). This discrepancy was more pronounced in patients with BEV than SEV (≥5 mmHg in 65% vs 21%, p<0.001), despite comparable invMG between THV types (5.0 vs 5.0 mmHg, p=0.43). Adjustment for PR generally mitigated the difference between non-invasive and invasive measurements, significantly reducing the number of patients with a discordance ≥5 mmHg (40% vs 12%; p<0.001 for echoMG and PRadjMG, respectively). However, while PRadjMG and invMG were similar for SEVs (4.8 vs 5.0 mmHg, p=0.92), a significant difference persisted in the BEV group (7.7 vs 5.0 mmHg, p<0.001). The use of CT-derived ascending aorta measurements to calculate PR yielded similar results, showing good correlation with echo-derived measurements (PR correlation coefficient = 0.98, 95% CI 0.98-0.99, p <0.001). Conclusions. Following TAVR, echocardiographic assessment systematically overestimates invasive trans-prosthetic gradients, particularly in BEVs. Adjustment of echoMG for PR is effective in patients with SEV but does not fully eliminate discrepancy with invasive measurements in BEVs. Pressure recovery analysis should be incorporated into routine echocardiographic follow-up after TAVR, although invasive assessment remains the gold standard for evaluating THV hemodynamic performance.