Prognostic value of invasive versus echocardiography-derived aortic gradient in patients undergoing TAVI

Recent studies report a discordance between invasive and echocardiography-derived gradients after transcatheter aortic valve implantation (TAVI) with balloon-expandable (BEV) and self-expanding valves (SEV). There are limited data on the determinants and clinical implications of this discordance. We aimed to examine the prognostic value of invasive and echocardiography-derived gradients after implantation of SEV and BEV and to compare gradients for SEV versus BEV. We performed a retrospective, propensity score-matched study. Invasive measurements were obtained before and immediately after TAVI. Echocardiography was performed before and within 24 hours after TAVI, and at 1 year. Clinical outcomes were assessed at 30 days, 1 year, and 2 years. The 1:1 propensity score matching resulted in 436 matched pairs (436 SAPIEN 3 and 436 Evolut). Invasive gradients post-TAVI independently predicted higher risk for all-cause mortality at 30 days, 1 year and 2 years as a continuous variable (hazard ratio [HR] 1.07, 95% confidence interval [CI]: 1.00-1.14; p=0.038; HR 1.06, 95% CI: 1.01-1.11; p=0.007; HR 1.05, 95% CI: 1.01-1.09; p=0.011, respectively) and by using >10 mmHg as a cutoff (HR 1.95, 95% CI: 1.13-4.78; p=0.028; HR 1.91, 95% CI: 1.11-3.65; p=0.030; HR 1.61, 95% CI: 1.03-2.96; p=0.021, respectively), but echocardiography-derived gradients did not (HR 1.13, 95% CI: 0.87-1.75; p=0.247; HR 1.02, 95% CI: 0.95-1.10; p=0.639; HR 0.99, 95% CI: 0.94-1.07; p=0.979, respectively). Mean gradients before and after TAVI were higher by echocardiography than by invasive measurements. The difference was more pronounced after implantation with BEV than SEV (7.0 [25th-75th percentile: 4.0-11.0] mmHg vs 5.0 [2.0-7.0] mmHg; p<0.001). Smaller valve size, higher ejection fraction and higher stroke volume amplified the discordance. Invasive mean gradients were similar after SEV and BEV (3.0 [0.0-6.0] mmHg vs 3.0 [0.0-6.0] mmHg; p=0.166), but echo-derived mean gradients were lower after SEV versus BEV (8.0 [6.0-11.0] mmHg vs 11.0 [8.0-14.0] mmHg; p<0.001). Only invasively measured but not echocardiography-derived transvalvular mean gradients correlate with 30-day, 1-year and 2-year mortality. Aortic gradient measurements are higher by echocardiography than by invasive assessment and more so for BEV than SEV. Smaller valve size, higher ejection fraction and higher stroke volume increase this discordance between echocardiography and invasive assessment.