Aortic insufficiency following transcatheter aortic valve replacement is underestimated by echocardiography compared with cardiac MRI
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KeywordsLeft Ventricular Ejection Fraction Transcatheter Aortic Valve Replacement Aortic Annulus Aortic Insufficiency Transthoracic Echocardiogram
The degree of aortic insufficiency (AI) after transcatheter aortic valve replacement (TAVR) has been identified as a predictor of increased mortality. Since even mild AI is associated with increased mortality in some studies, accurate quantification of post-TAVR AI is critical. Assessment of AI by echocardiography is typically performed by visual inspection and semi-quantitative methods. Most post-TAVR AI is paravalvular, however echocardiography has limited ability to quantify multiple eccentric paravalvular jets. Using flow quantification methods, cardiac MRI (CMR) may more accurately quantify AI severity post-TAVR and therefore more accurately assess risk in this population.
Twenty-three patients who underwent TAVR with a SAPIEN prosthesis were studied. All patients underwent an intraoperative transesophageal echocardiogram (TEE), as well as a post-procedure transthoracic echocardiogram (TTE) and CMR. Paravalvular AI by TTE and TEE was graded using color Doppler by quantifying the circumferential extent of AI as a percentage of the aortic annulus (none < 1%, trace 1-5%, mild 6-10%, moderate 11-30%, severe >30%) following recommendations from the Valve Academic Research Consortium. AI severity by CMR was quantified as the regurgitant fraction of forward aortic flow based on previously published recommendations (none <1%, trace 1-5%, mild 6-15%, moderate 16-48%, severe >48%).
CMR can reliably quantify post-TAVR AI. Echocardiography underestimates the severity of post-TAVR AI compared with CMR. CMR could be selectively utilized in patients with mild post-TAVR AI by echocardiography to screen for more significant AI. Further studies are needed to determine 1) whether echocardiography alone underestimates the risk of adverse outcomes related to post-TAVR AI, and 2) whether similar degrees of post-TAVR AI by CMR also translate into adverse outcomes.
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