Multislice spiral computed tomographic angiography of coronary arteries in patients with suspected coronary artery disease: an effective filter before catheter angiography?

BACKGROUND: Despite impressive image quality, it is unclear if noninvasive coronary angiography with multislice spiral computed tomography (CT) is powerful enough to act as a filter before invasive angiography (INV-A) in symptomatic patients. METHODS AND RESULTS: We therefore studied 133 consecutive symptomatic patients with suspected coronary artery disease (CAD) and an indication for INV-A (chest pain and signs of ischemia in conventional stress tests). Patients with known CAD, acute coronary syndrome, or a calcium volume score >1000 were excluded. In all patients, both INV-A and multislice CT angiography (MSCT-A) (Philips MX 8000 multislice spiral CT, scan time 250 milliseconds, slice thickness 1.3 mm, 120 mL of contrast agent, 4 mL/s, retrospective gating) were directly compared by 2 independent investigators using the American Heart Association 15-segment model. Altogether, we studied 1596 segments, 74% had diagnostic image quality. Multislice CT angiography correctly identified 68 significant stenoses of the 75 stenoses seen with INV-A (sensitivity 91%). In 945 of 1185 diagnostic segments, stenosis could correctly be ruled out with MSCT-A. There were 3 times more stenoses seen with MSCT-A compared with INV-A (positive predictive value 29%) mainly because of misclassification of nonobstructive plaques as stenosis. The per-patient analysis allowed to exclude significant CAD in 42 (32%) of 133 patients. In only 6 of 53 patients, MSCT-A failed to detect significant stenosis, 4 of those were in small segments not requiring intervention. Calcium scoring alone was less suited as a filter before angiography: 25 patients (18% of study group) had a calcium score = 0, and 8 of these patients turned out to have significant stenoses. CONCLUSION: Multislice CT angiography, but not calcium scoring alone, offers promise to reduce the number of INV-A in symptomatic patients with suspected CAD by up to one third with minimal risk for the patient.

[Invasive versus noninvasive (MSCT) coronary angiography. Importance of cardiac diagnostics with multislice computed tomography]. / Invasive versus nichtinvasive (MSCT) Koronarangiographie. Stellenwert der kardialen Diagnostik mittels Multislice-Computertomographie.

Cardiac imaging with fast computed tomography (CT) is a quickly evolving field starting to become established in the cardiac routine work-up. The exclusion of coronary calcification is the most accurate noninvasive method to exclude significant coronary stenosis whereas the detection of calcification identifies coronary arteriosclerosis. The total calcium load correlates with the risk of coronary stenosis, but there is not a 1 : 1 relationship. CT angiography with contrast enhancement offers promises to increase diagnostic accuracy. 4-slice scanners acquire data with a slide width down to 1 mm. The spatial resolution of invasive coronary angiography cannot be achieved yet. Severe coronary stenosis may be excluded with 90% specificity if image quality is not impaired by artifacts, severe calcification, arrhythmia, and a heart rate > 70 beats/min. With present technology, about 26% of segments may not be adequately assessed. Despite these limitations CT angiography is a useful tool to reduce the number of invasive diagnostic angiography. In patients with known coronary artery disease (CAD), progression as well as stent occlusion can be assessed. Instent stenosis can only be diagnosed indirectly. The patency of arterial and venous grafts can be assessed very well including also the bypass insertion site. Actual studies on the significance of noncalcified plaques are in progress.A CT angiography should take place in order to avoid further exposure to radiation. Therefore, patients with typical angina or significant signs of coronary ischemia have to be investigated by invasive methods and do not profit from a CT scan. Preparation and implementation of this method should only be applied in cooperation with radiologists and cardiologists in an experienced center.