Grading of aortic stenosis severity: a head-to-head comparison between cardiac magnetic resonance imaging and echocardiography

Aim: To prospectively evaluate the accuracy of cardiac magnetic resonance (cMR) imaging for the assessment of aortic valve effective orifice area (EOA) by continuity equation and anatomical aortic valve area (AVA) by direct planimetry, as compared with transthoracic (TTE) and transesophageal (TEE) two-dimensional (2D) echocardiography, respectively.Methods and results: A total of 31 patients (21 men, 10 women, mean age 69 ± 10 years) with moderate-to-severe aortic stenosis (AS) diagnosed by TTE and scheduled for elective aortic valve replacement, underwent both cMR and TEE. AVA by cMR was obtained from balanced steady-state free-precession cine-images. EOA was computed from phase-contrast MR flow analysis. AVA at cMR (0.93 ± 0.42 cm²) was highly correlated with TEE-derived planimetry (0.92 ± 0.32 cm²) (concordance correlation coefficient, CCC = 0.85). By excluding 11 patients with extensively thickened and heavily calcified cusps, the CCC increased to 0.93. EOA at cMR (0.86 ± 0.30 cm²) showed a strong correlation with TTE-derived EOA (0.78 ± 0.25 cm²) (CCC = 0.82). Conclusions: cMR imaging is an accurate alternative for the grading of AS severity. Its use may be recommended especially in patients with poor transthoracic acoustic windows and/or in case of discordance between 2D echocardiographic parameters.