Cardiovascular magnetic resonance reclassification of aortic regurgitation after transcatheter aortic valve implantation: A COMPARE-TAVI 1 substudy

Aortic regurgitation (AR) after transcatheter aortic valve implantation (TAVI) is a clinical concern. Echocardiography is routinely used to assess AR but relies on semiquantitative and operator-dependent measures, while cardiovascular magnetic resonance (CMR) allows direct quantification of regurgitant flow. This study compared transthoracic echocardiography (TTE) and CMR in assessing AR after TAVI using standardized Valve Academic Research Consortium-3 (VARC-3) criteria.

In this prespecified substudy of the multicenter COMPARE-TAVI 1 trial, patients were randomized to treatment with Sapien 3/Sapien 3 Ultra or Myval/Myval Octacor transcatheter heart valves. TTE and CMR were performed in 327 participants 4-6 weeks post-TAVI, and AR severity was graded according to VARC-3 criteria. TTE was evaluated by core laboratory consensus, whereas CMR-derived regurgitant fraction was quantified by phase-contrast velocity mapping. Agreement, diagnostic accuracy, and clinical predictors of discordance were evaluated.

By TTE, AR was none-trace-mild in 88.4% (289/327), mild-moderate in 10.1% (33/327), moderate in 0.9% (3/327), and moderate-severe in 0.6% (2/327) of patients. Corresponding CMR results were 92.7% (303/327), 7.0% (23/327), 0.3% (1/327), and 0%, with a median [IQR] AR fraction of 5% [3-9]. Overall agreement between modalities was 86% (281/327), with TTE overestimating AR in 9% (31/327) and underestimating in 5% (15/327) as compared with CMR. Using CMR as the reference for detecting moderate or greater AR (AR fraction ≥30%), TTE did not identify the one patient who had moderate AR by CMR. Of five patients graded as moderate or greater by TTE, all were downgraded by CMR to less than moderate AR (sensitivity 0.00, 95% CI 0.00-0.98; specificity 0.99, 95% CI 0.97-1.00). Discordance was more frequent with extensive aortic valve calcification and those receiving Myval/Myval Octacor valves.

In this multicenter study, current-generation transcatheter valves exhibit low rates of moderate or greater AR. One patient with moderate AR by CMR was not detected by TTE. CMR reclassified all five patients classified with moderate or greater AR by TTE to lower severity categories, underscoring the complementary value of CMR to TTE, when moderate or severe AR is suspected.