Core laboratory versus center-reported echocardiographic assessment of the native and bioprosthetic aortic valve

Abstract Background The use of a central echocardiographic core laboratory (ECL) is advised to minimize measurement variation and heterogeneity in clinical trials. Insights into quantitative differences between ECL and center-reported echocardiographic assessment of the native and bioprosthetic aortic valve are lacking. We aimed to explore clinically relevant differences between these evaluations. Methods Data were used from the PERIcardial SurGical AOrtic Valve ReplacemeNt (PERIGON) Pivotal Trial for the Avalus valve. In this trial, patients with an indication for surgical aortic valve replacement (SAVR) due to aortic stenosis or regurgitation (AR) were enrolled. Serial echocardiographic examinations were performed at each center and reanalyzed by an independent ECL. For the bioprosthetic valve analysis, postoperative data throughout 5-year follow-up were pooled. Differences between the ECL and the centers in continuous parameters were quantified in mean differences and intraclass correlation coefficients (ICCs). Between-center differences were illustrated by plotting standardized mean differences (SMDs) between centers and the ECL for the 10 sites that implanted the most prostheses. Agreement on AR, paravalvular leak (PVL), and prosthesis-patient mismatch (PPM) classification was investigated using Cohen’s kappa coefficients. Results The analysis on the native aortic valve was performed on 1118 patients. The relative mean difference was largest for the left ventricular outflow tract (LVOT) area, followed by stroke volume and effective orifice area (index), with center-reported values being 11-7% higher (Table 1). High ICCs of around 0.90 were observed for peak aortic jet velocity, mean pressure gradient, and the velocity-time integral across the aortic valve. More than 5000 echocardiograms were available for the bioprosthetic valve analysis. Therein, comparable results were observed. In Figure 1, differences in assessment on center level are illustrated. The SMDs for peak velocity were between 0 and 0.5 for all centers, while there was more heterogeneity between centers for other parameters. The kappa coefficient was 0.59 (95% confidence interval [CI] 0.56, 0.63) for agreement on native AR, 0.28 (95% CI 0.18, 0.37) for PVL, and 0.42 (95% CI 0.40, 0.44) for PPM. Conclusions For echocardiographic assessment of the native and bioprosthetic aortic valve, agreement between the ECL and the clinical centers varies by parameter and by center. There is high agreement on continuous-wave Doppler-related measurements. On the contrary, agreement is low for parameters that involve measurement of the LVOT diameter. These results provide important context for the interpretation of aortic valve performance in studies that lack central ECL evaluation.