Aortic Valve Area Calculation in Aortic Stenosis by CT and Doppler Echocardiography

作者：Clavel Marie Annick^*; Malouf Joseph; Messika Zeitoun David; Araoz Phillip A; Michelena Hector I; Enriquez Sarano Maurice

来源：JACC: Cardiovascular Imaging , 2015, 8(3): 248-257.

DOI：10.1016/j.jcmg.2015.01.009

• aortic valve stenosis
• diagnostic method echocardiography
• multidetector CT
• survival

OBJECTIVES The aim of this study was to verify the hypothesis that multidetector computed tomography (MDCT) is superior to echocardiography for measuring the Left ventricular outflow tract (LVOT) and calculating the aortic valve area (AVA) with regard to hemodynamic correlations and survival outcome prediction after a diagnosis of aortic stenosis (AS).
BACKGROUND MDCT demonstrated that the LVOT is noncircular, casting doubt on the AVA measurement by 2-dimensional (2D) echocardiography.
METHODS A total of 269 patients (76 +/- 11 years of age, 61% men) with isolated calcific AS (mean gradient 44 +/- 18 mm Hg; ejection fraction 58 +/- 15%) underwent Doppler echocardiography and MDCT within the same episode of care. AVA was calculated by echocardiography (AVA(Echo).) and by MDCT (AVA(CT)) using each technique measurement of LVOT area. In the subset of patients undergoing dynamic 4-dimensional MDCT (n = 135), AVA was calculated with the LVOT measured at 70% and 20% of the R-R interval and measured by planimetry (AVA(Plani)).
RESULTS Phasic measurements of the LVOT by MDCT yielded slight differences in eccentricity and size (all p < 0.001) but with excellent AVA correlation (r = 0.92, p < 0.0001) and minimal bias (0.05 cm(2)), whereas the AVA(Plant), showed poor correlations with all other methods (all r values <0.58). AVA(CT) was Larger than AVA(Echo) (difference 0.12 +/- 0.16 cm(2); p < 0.0001) but did not improve outcome prediction. Correlation gradient-AVA was slightly better with AVA(Echo). than AVA(CT) (r = -0.65 with AVA(Echo) vs. -0.61 with AVA(CT); p = 0.01), and discordant gradient-AVA. was not reduced. For Long-term survival, after multivariable adjustment, AVA(Echo) or AVA(CT) were independently predictive (hazard ratio [HR]: 1.26, 95% confidence interval [Cl]: 1.13 to 1.42; p < 0.0001 or HR: 1.18, 95% Cl; 1.09 to 1.29 per 0.10 cm(2) decrease; p < 0.0001) with a similar prognostic value (p >= 0.80). Thresholds for excess mortality differed between methods: AVA(Echo) <= cm(2) (HR: 4.67, 95% Cl: 2.22 to 10.50; p < 0.0001) versus AVA(CT) <= cm(2) (HR: 3.16, 95% CI: 1.64 to 6.43; p = 0.005), with simple translation of spline-curve analysis.
CONCLUSIONS Head-to-head comparison of MDCT and Doppler echocardiography refutes the hypothesis of MDCT superiority for AVA calculation. AVA(CT) is larger than AVA(Echo) but does not improve the correlation with transvalmular gradient, the concordance gradient-AVA, or mortality prediction compared with AVA(Echo). Larger cut-point values should be used for severe AS if AVA(CT) (<1.2 cm(2)) is measured versus AVA(Echo) (<1.0 cm(2)).

• 出版日期2015-3