Magnetic resonance to assess the aortic valve area in aortic stenosis: how does it compare to current diagnostic standards?

OBJECTIVES: The purpose of the present study was to evaluate whether magnetic resonance (MR) planimetry of the aortic valve area (AVA) may prove to be a reliable, non-invasive diagnostic tool in the assessment of aortic valve stenosis, and how the results compare with current diagnostic standards.

BACKGROUND: Current standard techniques for assessing the severity of aortic stenosis include transthoracic and transesophageal echocardiography (TEE) as well as transvalvular pressure measurements during cardiac catheterization.

METHODS: Forty consecutive patients underwent cardiac catheterization, TEE, and MR. The AVA was estimated by direct planimetry (MR, TEE) or calculated indirectly via the peak systolic transvalvular gradient (catheter). Pressure gradients from cardiac catheterization and Doppler echocardiography were also compared.

RESULTS: By MR, the mean AVA(max) was 0.91 +/- 0.25 cm(2); by TEE, AVA(max) was 0.89 +/- 0.28 cm(2); and by catheter, the AVA was calculated as 0.64 +/- 0.26 cm(2). Mean absolute differences in AVA were 0.02 cm(2) for MR versus TEE, 0.27 cm(2) for MR versus catheter, and 0.25 cm(2) for TEE versus catheter. Correlations for AVA(max) were r = 0.96 between MR and TEE, r = 0.47 between TEE and catheter, and r = 0.44 between MR and catheter. The correlation between Doppler and catheter gradients was r = 0.71.

CONCLUSIONS: Magnetic resonance planimetry of the AVA correlates well with TEE and less well with the catheter-derived AVA. Invasive and Doppler pressure correlated less well than those obtained from planimetric techniques. Magnetic resonance planimetry of the AVA may provide an accurate, non-invasive, well-tolerated alternative to invasive techniques and transthoracic echocardiography in the assessment of aortic stenosis.