Diagnostic value of cardiac 64-slice computed tomography: importance of coronary calcium.
OBJECTIVE
Coronary computed tomography angiography (CTA) has proven clinically useful for non-invasive assessment of coronary pathology. However, coronary calcium can reduce its diagnostic value. The objective of this study was to define a calcium score above which CTA appears less reliable.


METHODS
We prospectively investigated 109 patients referred for elective coronary angiography (CA). With a 64-slice CT-scanner, coronary calcium was determined and expressed in Agatston unit (AU). A significant coronary stenosis was defined as > or =50% luminal diameter reduction. Following blinded interpretation, diagnostic values of CTA at different levels of AU were calculated using quantitative CA as reference.


RESULTS
A strong association with stent and the severity of coronary calcium was observed. In patients without stents (n = 91) sensitivity, specificity and positive and negative predictive value for presence of significant stenosis were: 100%, 91%, 74%, and 100% in patients with a calcium score < or =400 AU versus 100%, 17%, 75%, and 100% in patients with a score >400 AU.


CONCLUSIONS
The diagnostic accuracy of CTA in patients with no or little coronary calcium is excellent. However, in patients with an Agatston score >400 specificity declines and therefore, these patients should not go on to CTA, but be referred to CA instead.
Diederichsen
Axel C P
AC
Department of Cardiology, Odense University Hospital, Denmark. a.diederichsen@dadlnet.dk
Petersen
Henrik
H
Jensen
Lisette O
LO
Thayssen
Per
P
Gerke
Oke
O
Sandgaard
Niels C F
NC
Høilund-Carlsen
Poul F
PF
Mickley
Hans
H
D000368:Aged; D015906:Angioplasty, Balloon, Coronary / Q000295:instrumentation; D002114:Calcinosis / Q000000981:diagnostic imaging* / Q000628:therapy; D017023:Coronary Angiography / Q000379:methods*; D023921:Coronary Stenosis / Q000000981:diagnostic imaging* / Q000628:therapy; D003718:Denmark; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D015607:Stents; D014057:Tomography, X-Ray Computed