A study published in the Sept. 27 issue of the Journal of the American College of Cardiology found that, in emergency department (ED) patients experiencing low-risk, acute chest pain, the use of early coronary computed tomographic angiography (CCTA) is a more rapid and cost-efficient test than rest-stress myocardial perfusion imaging (MPI). An editorial in the same issue of the journal, while acknowledging the study’s conclusions in some cases, stressed that there are many factors that could make other tests besides CCTA more beneficial.
The study, by James A. Goldstein, MD, of William Beaumont Hospital in Royal Oak, Mich., and colleagues aimed to compare the efficiency, cost and safety of employing CCTA vs. MPI in the evaluation of acute, low-risk chest pain, which sends more than 8 million patients to EDs each year.
Randomized clinical trials were performed in 16 EDs with 361 patients randomly assigned to CCTA and 338 patients randomly assigned to MPI as the index noninvasive test.
The CCTA resulted in a 54 percent reduction in time to diagnosis compared with MPI, with median times of 2.9 and 6.3 hours, respectively, according to Goldstein et al. Costs were also reduced by 38 percent without any major differences in adverse cardiac events after the normal index testing.
Based on the results, the authors concluded that CCTA is faster and more cost-effective than MPI, which is the predominant noninvasive approach to test for coronary artery disease (CAD) among patients suffering from chest pain.
An editorial comment from Michael Salerno, MD, PhD, and colleagues from the University of Virginia in Charlottesville echoed some of the findings of Goldstein et al, while also recognizing improvements in the MPI protocol that could alter the outcomes of that strategy.
Salerno and colleagues noted the excellent negative predictive value (NPV) of 99 percent for CCTA, emphasizing its usefulness in excluding significant stenoses in ED patients with a low to intermediate likelihood of CAD. Since CCTA is faster than MPI, this could impact the triage of chest pain patients in the ED.
But Salerno et al also pointed out that the rest-stress MPI protocol used in the study may have contributed to the longer time to diagnosis for the strategy. The Goldstein et al study was conducted from June 2007 to November 2008, and in the years since, EDs have begun using stress-only protocols for low-risk patients without acute electrocardiography (ECG) changes. This protocol would have reduced time to diagnosis, according to Salerno et al, who also suggested that an exercise ECG stress test alone would be feasible for patients at low risk for acute coronary syndrome (ACS), likely making that strategy more cost-effective than any imaging strategy.
Technical advances could also soon improve the speed of MPI while also lowering radiation dose for MPI and CCTA, according to Salerno et al.
Still, Salerno and colleagues concluded that CCTA, with its excellent NPV, is a useful imaging approach for patients at low risk for ACS or CAD. For patients not eligible for CCTA, other imaging approaches, or even some non-imaging approaches, may be more beneficial, with advancements in technology and technique constantly improving the accuracy and efficiency of the various strategies, the researchers added.