The use of cardiac computed tomography angiography (CCTA) can help emergency department physicians make better decisions about which patients with symptoms suggestive of acute coronary syndromes can safely be sent home.
There were no undetected cases of acute coronary syndromes (ACS) in patients assessed with CCTA or standard evaluation, suggesting that the earlier and greater number of discharges in the CCTA group did not result in any missed diagnoses in a prospective, randomized trial of 1,000 patients.
Dr. James E. Udelson
"It’s really about what is the minimum testing that you can do to safely send someone home if you’re an emergency department physician," senior author Dr. James E. Udelson said in an interview. Each ED and each ED physician had their own criteria for when a patient could be discharged based on CCTA findings. "We’re really measuring not the performance of the test, but how the test affects decision making," he said.
Previous studies have suggested that CCTA may aid in safer and earlier triage of low-risk patients and that it can rule out coronary artery disease faster than stress myocardial-perfusion imaging. However, CCTA often can involve more follow-up procedures and greater costs than functional testing.
While the accuracy of CCTA was roughly equivalent to that of standard ED evaluation, the imaging technique also cost about the same. There was no difference in total costs between the two groups for the index visit and during 28-day follow-up in a subgroup of 649 patients from five of nine sites, in which complete billing data were available. Costs for patients with CCTA appeared to be driven by a greater use of additional diagnostic testing.
In ROMICAT-II (Rule Out Myocardial Infarction/Ischemia Using Computer Assisted Tomography II), researchers pitted CCTA – as a first diagnostic test, performed as early as possible – against standard ED evaluation in 1,000 patients with acute chest pain suggestive of ACS (N. Engl. J. Med. 2012;367:299-308).
The average length of the hospital stay – the primary end point – for patients who underwent CCTA was 7.6 hours less than that of the standard evaluation group.
Patient enrollment began in April 2010 and ended in January 2012 at nine U.S. hospitals. All sites were required to use at least 64-slice CT. Eligible patients were 40-74 years of age, and presented to the ED with chest pain (or the anginal equivalent) of at least 5 minutes’ duration within 24 hours before presentation in the ED. They also had to be in sinus rhythm and warranted further risk stratification to rule out acute coronary syndromes.
Patient care was not mandated by the study protocol in either group, but instead was at the discretion of local physicians. The discharge diagnosis also was based on the local physicians’ assessment.
Of 1,000 enrolled patients, 501 were randomized to CCTA and 499 were assigned to a standard evaluation. All patients were included in the intention-to-treat analysis. Overall, 987 patients (99%) had complete follow-up at 28 days.
After a complete evaluation, 75 patients (8%) had a final diagnosis of an acute coronary syndrome. In this subgroup of patients with a final diagnosis of ACS, the length of stay in the hospital was similar after CCTA and after standard evaluation in the ED.
In the overall cohort and also in patients without a final diagnosis of ACS, the mean time to diagnosis was significantly decreased with CCTA, compared with a standard evaluation. Patients in the CCTA group were more often directly discharged from the ED (47%, compared with 12% of patients in the standard-evaluation group), with fewer admissions to an observation unit.
Overall, there were eight major adverse cardiovascular events during the 28-day follow-up: six after standard evaluation in the ED and two after CCTA.
The results have important implications for some EDs. Not all EDs are the same: Some are overflowing with patients, while others have light traffic. For directors of busy and crowded EDs, the findings provide "an opportunity to get people out a lot sooner," said Dr. Udelson, chief of the cardiology division at Tufts Medical Center in Boston.
Half of patients who presented to the ED with symptoms suggestive of ACS and who underwent CCTA were discharged within 8.6 hours. In contrast, it took more than a day (26.7 hours) for half of the patients in the standard-evaluation group to be discharged. "If you’re in a supercrowded ED, that’s really worth something," he said.
The researchers did not measure additional follow-up in this study beyond major events that may have happened within 30 days. However, "one of the things about CT is that you identify early disease. You can potentially be comfortable that it doesn’t have anything to do with the chest pain." Primary care physicians should know about this early disease, in order to potentially start or change treatment.