Measurement of aortic valve calcification using multislice computed tomography: correlation with haemodynamic severity of aortic stenosis and clinical implication for patients with low ejection fraction.
BACKGROUND
Measurement of the degree of aortic valve calcification (AVC) using electron beam computed tomography (EBCT) is an accurate and complementary method to transthoracic echocardiography (TTE) for assessment of the severity of aortic stenosis (AS). Whether threshold values of AVC obtained with EBCT could be extrapolated to multislice computed tomography (MSCT) was unclear and AVC diagnostic value in patients with low ejection fraction (EF) has never been specifically evaluated.


METHODS
Patients with mild to severe AS underwent prospectively within 1 week MSCT and TTE. Severe AS was defined as an aortic valve area (AVA) of less than 1 cm(2). In 179 patients with EF greater than 40% (validation set), the relationship between AVC and AVA was evaluated. The best threshold of AVC for the diagnosis of severe AS was then evaluated in a second subset (testing set) of 49 patients with low EF (≤40%). In this subgroup, AS severity was defined based on mean gradient, natural history or dobutamine stress echocardiography.


RESULTS
Correlation between AVC and AVA was good (r=-0.63, p<0.0001). A threshold of 1651 arbitrary units (AU) provided 82% sensitivity, 80% specificity, 88% negative-predictive value and 70% positive-predictive value. In the testing set (patients with low EF), this threshold correctly differentiated patients with severe AS from non-severe AS in all but three cases. These three patients had an AVC score close to the threshold (1206, 1436 and 1797 AU).


CONCLUSIONS
In this large series of patients with a wide range of AS, AVC was shown to be well correlated to AVA and may be a useful adjunct for the evaluation of AS severity especially in difficult cases such as patients with low EF.
Cueff
Caroline
C
Cardiology Department, AP-HP, Bichat Hospital, Paris, France.
Serfaty
Jean-Michel
JM
Cimadevilla
Claire
C
Laissy
Jean-Pierre
JP
Himbert
Dominique
D
Tubach
Florence
F
Duval
Xavier
X
Iung
Bernard
B
Enriquez-Sarano
Maurice
M
Vahanian
Alec
A
Messika-Zeitoun
David
D
D000368:Aged; D000369:Aged, 80 and over; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D001783:Blood Flow Velocity / Q000502:physiology; D002114:Calcinosis / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D015588:Observer Variation; D012680:Sensitivity and Specificity; D013318:Stroke Volume / Q000502:physiology; D014057:Tomography, X-Ray Computed / Q000379:methods*