Prognostic value of coronary computed tomographic angiography for prediction of cardiac events in patients with suspected coronary artery disease

Abstract

Objectives: We assessed the rate of cardiac events after detection or exclusion of obstructive coronary artery disease (CAD) by coronary computed tomography angiography (CCTA).

Background: Several studies have demonstrated a high diagnostic accuracy of CCTA for detection of obstructive CAD compared with invasive angiography, but data regarding the clinical prognostic value of CCTA are limited.

Methods: In all, 1,256 consecutive patients with suspected CAD undergoing 64-slice CCTA in our institution between October 2004 and September 2006 were observed prospectively for the occurrence of severe cardiac events (cardiac death, myocardial infarction, or unstable angina requiring hospitalization: primary study end point) and all cardiac events (additionally including revascularization >90 days after CCTA). The observed rate of all cardiac events was compared with the event rate predicted by the Framingham risk score. Obstructive CAD was defined as > or = 50% diameter stenosis in any coronary artery.

Results: During a median follow-up of 18 months (interquartile range 14 to 25 months), the overall rates of severe and all cardiac events were 0.6% and 1.8%, respectively. In 802 patients without obstructive CAD, there were 4 cardiac events, of which 1 was severe, whereas in 348 patients with obstructive CAD, there were 17 cardiac events, of which 5 were severe. The difference between the 2 groups was highly significant both for severe events (odds ratio: 17.3, 95% confidence interval: 3.6 to 82.5) and for all cardiac events (odds ratio: 16.1, 95% confidence interval: 7.2 to 36.0; both p < 0.001). The rate of all cardiac events in patients without obstructive CAD was significantly lower than predicted by the Framingham risk score (p = 0.01).

Conclusions: In patients with suspected CAD, CCTA has a significant prognostic impact on the prediction of cardiac events for the subsequent 18 months. The exclusion of obstructive CAD by CCTA identifies a patient population with an event risk lower than predicted by conventional risk factors.