By Chris Kaiser, Cardiology Editor
March 29, 2012
Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine, Harvard Medical School, Boston and Dorothy Caputo, MA, RN, BC-ADM, Nurse Planner
CHICAGO — Results from a second trial reported here confirmed the value of initial coronary CT angiography (CCTA) scan in the emergency department for evaluation and management of lower-risk patients with chest pain.
With a randomized cohort of 1,000 patients, researchers found that an initial CCTA scan significantly shortened the hospital length of stay compared with standard care (mean 23 versus 31 hours, P<0.0002), Udo Hoffmann, MD, MPH, from Massachusetts General Hospital in Boston, reported here at the American College of Cardiology meeting.
And faster discharge did not pose a safety risk, as there were no missed cases of acute coronary syndrome within the first 72 hours post discharge and only two major adverse events at 28 days.
There also were no missed cases of acute coronary syndrome at 72 hours in the standard care arm, but that group had five major adverse events during the 28-day follow-up.
Earlier this week Harold I. Litt, MD, from the University of Pennsylvania in Philadelphia, reported at ACC12 similar results from the ACRIN PA study: earlier discharge and no events in the group randomized to the CCTA strategy.
The CT-STAT study, published last year in the Journal of the American College of Cardiology, also found favorable results for utilizing CCTA in the emergency department for low- to intermediate-risk patients. CT-STAT, however, compared CCTA to SPECT myocardial perfusion imaging.
The current study, ROMICAT II (Rule Out Myocardial Ischemia/Infarction Using Computer Assisted Tomography), as well as ACRIN PA, allowed local physicians to order the desired stress test: exercise, echocardiography, or SPECT.
“The clinical evidence from these three trials is consistent,” said study discussant Matthew J. Budoff, MD, from UCLA Medical Center. “Physicians can feel confident discharging patients who have a negative CCTA scan.”
The ROMICAT I study, a blinded observational study published last year in JACC: Cardiovascular Imaging, demonstrated that those cleared of a cardiac cause of their chest pain had very good prognosis over two years, Hoffmann said.
ROMICAT II randomized 1,000 acute chest pain patients from nine centers in the U.S. between April 2010 and January 2012 to the CCTA strategy or standard care. Follow-up was nearly 100% in both groups.
The mean age of patients was 54 and 46% were women. About 37% of patients had zero or one risk factor, 53% had two or three, and 10% had four or more. The chief patient complaint at presentation was anginal chest pain (90%).
At discharge, 8.6% and 6.4% of patients in the CCTA and standard care arms, respectively, had a diagnosis of acute coronary syndrome. Hoffmann noted the “excellent” agreement between the sites and independent adjudication for discharge diagnosis (96.5%, kappa 0.9).
Along with an overall absolute difference of 8 hours in length of stay between the two arms, when the final diagnosis was not acute coronary syndrome, CCTA allowed for even quicker discharge (17 versus 27 hours, P<0.001). There was no difference in length of stay when patients were diagnosed with acute coronary syndrome.
Interestingly, between 12 and 18 hours, the CCTA arm had three times as many patients discharged than standard care (60% versus 20%).
Also, the CCTA arm had three times the number of patients discharged directly from the emergency department, half the number admitted for observation, and a mean time to diagnosis of 10 hours compared with 19 hours for the standard care patients.
When patients had a negative CCTA scan, the mean cost of care was 19% lower than standard care. But when patients in the CCTA arm were admitted to the hospital, their cost doubled compared with standard care patients.
The cost increase was mainly driven by the implantation of stents or bypass surgery. Overall, however, the costs balanced out.
“We were happy to see there was no overall increase in cost,” Hoffmann said.
However, the study only allowed enrollment during normal weekly business hours. It was noted that if the strategy expands to 24/7 availability, the initial costs and downstream costs could increase.
Hoffmann pointed out that none of the nine sites in the study had routinely used CCTA in the emergency department for chest pain patients. Whether they will continue using CCTA in this manner remains to be seen.
“The physicians know the findings of this study. Now they have to determine their own threshold as to where they are comfortable with the technology,” he said.
Radiation exposure is a topic that always surfaces when discussing cardiac CT scanning, and Hoffmann’s presentation did not disappoint.
He said that the cumulative radiation exposure, including from CCTA, SPECT, and catheter angiography during the index visit and follow-up, was three times as high in the CCTA arm: 14 mSv versus 5 mSv.
Discussant Elliott Antman, MD, from Brigham and Women’s Hospital in Boston, suggested that patients could be exposed to even higher radiation if they went to different hospitals that weren’t aware of their previous CT scans.
Hoffmann noted that in CT-STAT, which compared CCTA to SPECT, the radiation exposure favored CT: 11 versus 14 mSv.
“This trial is biased in a way because all patients in the CT arm had coronary CT, but only 40% of patients in the other arm had a test that exposed them to radiation,” he said.
Newer CT technology allows the radiation dose to be cut by 50%, he said. And some state-of-the-art scanners can deliver doses as low as 3 mSv.
“Remember, we have to balance the improved decision making, which frees up beds in the hospital, and lower rates of false diagnostic catheter angiographies,” he said.
But, he acknowledged, electronic medical records that document a patient’s previous CCTA scans could help determine whether another CT scan is warranted.
The study was supported by the National Heart, Lung, and Blood Institute.
Hoffman reported a relationship with Siemens Medical Systems. Some of the co-authors reported relationships with Qi Imaging, St. Jude Medical, Astellas Pharma, Medtronic, Lantheus Medical, Siemens Medical Systems, Alere-Biosite, Brahms-Thermo Fisher Scientific, Nanosphere, and Clindevor.
Primary source: American College of Cardiology
Source reference: Hoffmann U, et al “ROMICAT II — Rule out myocardial ischemia/infarction using computer assisted tomography” ACC 2012.
Additional source: Journal of the American College of Cardiology
Source reference: Goldstein J, et al “The CT-STAT coronary computed tomographic angiography for systematic triage of acute chest pain patients to treatment trial” J Am Coll Cardiol 2011; 58: 1414-1422.