Galen has bluntly chimed in on the study comparing exercise stress testing and calcium scores from electron beam computed tomography (EBCT) that the lay press has been reporting.
As we brace ourselves for patients demanding EBCT, let’s consider the data and recommendations. Again, UptoDate comes in handy:
Coronary calcification detected by EBCT is found in individuals who have significant angiographic CHD, with a sensitivity ranging from 90 to 100 percent, a specificity of 45 to 76 percent, a positive predictive accuracy of 55 to 84 percent, and a negative predictive accuracy of 84 to 100 percent . . .In 2000, the American College of Cardiology/American Heart Association (ACC/AHA) published an Expert Consensus Document that made recommendations concerning the use of EBCT that have been controversial [61]. The panel raised questions about the reported low specificity of EBCT calcium scores and concluded that EBCT cannot be recommended for the diagnosis of obstructive CHD because of its low specificity, which can result in additional expensive and unnecessary testing to rule out a diagnosis of CHD. However, subsequent data have suggested that EBCT calcium scoring is cost effective when applied to symptomatic patients at low to intermediate pretest likelihood for obstructive CHD [62] and that, when analysis for verification bias is performed, specificity is higher [34].
At present, there are insufficient data to recommend the use of EBCT calcium scoring as a single diagnostic modality for screening of low risk, asymptomatic subjects; however, there are data to support its use in the “intermediate” risk asymptomatic patient in whom the contribution of multiple sub-threshold risk factors is difficult to determine using conventional risk assessment strategies.
There you have it. EBCT has no role in asymptomatic, low risk patients. It has a role in intermediate risk patients where conventional stress testing cannot be done. Helpful data to answer the onset of patient inquiries tomorrow.
