Comparison of Prognostic Usefulness (Three Years) of Computed Tomographic Angiography Versus 64-Slice Computed Tomographic Calcium Scanner in Subjects Without Significant Coronary Artery Disease

Coronary computerized tomographic angiography (CTA) has been used as a noninvasive method for ruling out high-grade stenoses. Even in the absence of such stenoses, analysis of coronary atherosclerosis may provide for important prognostic information, and this may be superior to exclusive coronary artery calcium scoring. We tested this hypothesis in patients undergoing CTA for clinical indications who had no stenoses requiring revascularization. From December 2004 to December 2006, 706 consecutive patients who underwent CTA but had no high-grade stenoses were included (58% men, mean age 59 ± 11 years). CTA and coronary artery calcium scoring (Agatston method) were performed using a 64-slice CT scanner with a gantry rotation time of 330 ms. CT angiograms were categorized as completely normal (group 1), showing minor plaque (group 2), or showing intermediate stenoses (group 3). Follow-up information was obtained in 670 patients (95%) over a mean of 3.2 years. There were 31 major adverse events (5%), namely 9 deaths (all noncoronary), 2 myocardial infarctions, 5 strokes, 13 coronary revascularization procedures (percutaneous or surgical >6 months after CTA), and 2 peripheral percutaneous interventions. Coronary status as defined by CTA was predictive of major events after adjustment for age and gender. In group 1, the probability of event-free survival at 3 years was 100%; in group 2, it was 96%; and in group 3, it was 91%. Compared to group 1, the risk in group 2 was increased 2.3-fold, and in group 3, it was increased 5.6-fold after adjusting for age and gender. However, after addition of the coronary artery calcium score to the regression analysis, CT angiographic status no longer appeared to be predictive. In conclusion, the risk of a major adverse cardiovascular event or death increased in a graded manner with degree of coronary atherosclerosis as defined by CTA even in the absence of high-grade coronary stenoses. However, in the absence of high-grade stenoses, we were unable to demonstrate a superior prognostic value of CTA compared to coronary artery calcium.