Routine use of coronary computed tomography as initial diagnostic test for angina pectoris

Coronary computed tomography (CCT) detects coronary obstruction with high sensitivity and might be useful for diagnosis of angina pectoris.

In this pilot study, we sought to prospectively evaluate the performance of CCT as initial work up and determine the significance of this strategy according to the pretest likelihood of having coronary artery disease (CAD).

One hundred and eighty patients with chest discomfort and suspected angina were prospectively referred for CCT with a 64-slice CT scan. Invasive coronary angiography (ICA) was performed on the basis of CCT findings (stenosis>50%). Patients were classified into tertiles according to estimated pretest probability of obstructive CAD using the Duke Clinical Score (low, intermediate and high). Strategy failure was defined as unnecessary ICA or major adverse cardiac event (MACE) within 6 months in patients without significant stenosis by CCT.

Pretest probability for CAD was 53 ± 29%. Significant stenosis was detected by CCT in 51 patients; 47 (26%) underwent ICA. Sixteen strategy failures were reported: 15 patients (10%) were referred for ICA that did not confirm significant coronary stenosis and one MACE occurred in a patient without significant stenosis by CCT. Strategy failures were 8% in low-probability, 1.7% in intermediate-probability and 15% in high-probability patients (P=0.03).

CCT as an initial step for angina diagnosis is most effective in patients with an intermediate probability of CAD. In patients with low or high likelihood, it is associated with a high rate of unnecessary ICA but not with adverse events.