What is the efficacy of CT scanning for cardiac assessment?

Updated: Nov 20, 2018
  • Author: Richard S Krause, MD; Chief Editor: Barry E Brenner, MD, PhD, FACEP  more...
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Answer

Studies have investigated the use of CCT in the emergency department (ED). These studies report a NPV of 97-100%. For example, in one study, CCT was performed in 192 patients presenting to the ED with chest pain, with an average follow-up interval of 50 months. The NPV of the test was 99%. Patients with the absence of coronary artery calcium (CAC) had a 0.6% annual cardiovascular event rate. In another study of ED chest pain patients, a negative test result (absence of coronary calcification) was associated with a very low adverse event rate over a 7-year follow-up period. Increasing score quartiles were strongly correlated with risk (P< 0.001). [30] Another recent study evaluated 1,031 patients admitted to an observation unit with CCT. Only two events occurred in 625 patients with a calcium score of 0 (0.3%; 95% confidence interval, 0.04-1.1%). [31]

The absence of detectable calcium has a very high NPV for ruling out obstructive coronary artery disease (CAD) and confers an excellent long-term prognosis for future cardiac events. Thus, use in low-risk patients is the most important application of CCT. An NPV of 98% has been reported for coronary chest pain or myocardial infarction in patients with acute symptoms and nonspecific ECG results. [32, 33]

As with other noninvasive techniques, CCT cannot be used to identify or rule out the presence of an unstable plaque. A problem with the use of CCT is that calcification is present much more often than significant stenosis. Most patients with coronary calcification who go on to conventional invasive catheter angiography will therefore not have significant obstructive disease. CCTA may be a less invasive alternative in these cases, but there are limitations of the currently available data for CCTA. These include the fact that most reports have been based on single-center experiences and have been conducted with a subset of symptomatic middle-aged white men who had a high prevalence of CAD. Multicenter trials and studies with intermediate-risk populations are warranted.


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