Diagnostic COncordance in Aortic Regurgitation Severity AssessMent: A ComPARative Study Between Cardiologists With Different Level of Expertise, the COMPARE-AR Study.

PURPOSE: Accurate echocardiographic assessment of chronic aortic regurgitation (AR) is challenging and subject to interobserver variability. We aim to evaluate reproducibility of guideline-recommended echocardiographic parameters in real-world practice and to assess cardiac magnetic resonance (CMR) as a complementary modality.

METHODS

We retrospectively analyzed 99 patients referred to us for transthoracic echocardiography (TTE) for AR evaluation. A subset of 22 patients also underwent CMR. AR severity was independently graded according to ESC and ASE guidelines by two expert cardiologists and two trainees using semi-quantitative and quantitative parameters: pressure half-time (PHT), vena contracta width (VCW), and PISA-derived parameters, such as regurgitant orifice area (EROA). Interobserver agreement was analyzed using Cohen's Kappa, Bland-Altman analysis, and intraclass correlation coefficients.

RESULTS

VCW showed the highest reproducibility (overall κ = 0.77), strong agreement across groups (EXACT team κ = 0.7, TRAIN team κ = 0.86), and high feasibility (68.7%). PHT demonstrated poor interobserver consistency (overall κ = 0.36), wide intra-team variability (EXACT team κ = 0.30 vs. TRAIN team κ = 0.39), and high feasibility (77.8%). EROA showed moderate agreement (overall κ = 0.55, EXACT team κ = 0.64, TRAIN team κ = 0.74) and low feasibility (30.3%). CMR-derived parameters (forward flow, backflow, and regurgitant fraction) displayed excellent reproducibility even between novice and expert readers.

CONCLUSIONS

VCW is the most reliable echocardiographic parameter for AR assessment, while PHT and EROA are limited by variability and feasibility, respectively. Given its reproducibility and independence from operator expertise, CMR should be considered early when TTE findings are inconclusive. A simplified TTE-first approach, followed by timely CMR, may optimize staging and management of chronic AR.