Close to the Heart
CCTA used to rule out acute coronary syndrome in the ED.
In the past, patients who were at risk for acute coronary syndrome (ACS) faced a lengthy stay at the hospital.
New findings by ACRIN® researchers, however, show that coronary CT angiography (CCTA) performed on patients presenting to the emergency department (ED) with low-to-intermediate risk for ACS appears safe and allows expedited discharge of many patients. The findings were presented at the 61st Annual Scientific Session of the American College of Cardiology on March 26, 2012, which coincides with ACRIN study results published in the New England Journal of Medicine.
ACRIN PA 4005, A Randomized Controlled Study of a Rapid "Rule Out" Strategy Using CT Coronary Angiogram Versus Traditional Care for Low- to Intermediate-Risk ED Patients with Potential Acute Coronary Syndromes, is the first trial carried out under the auspices of the ACRIN Cardiovascular Committee. In a 2:1 ratio, the study randomized low- to intermediate-risk chest pain participants either to the CCTA arm (908 participants) or to the traditional care arm (462 participants), which includes additional testing and observation.
Participants in the CCTA arm were discharged if test results were negative and were interviewed by telephone 30 days after discharge to determine whether any notable cardiac events had occurred. Participants with imaging results indicative of a heart muscle injury were admitted to the hospital for further care.
The study concluded that participants who underwent a CCTA were more than twice as likely to be discharged (49.6 versus 22.7 percent) and had significantly shorter hospital stays than those who received traditional care (median, 18.0 versus 24.8 hours). There were no deaths or cardiac arrests within 30 days of presentation among the 640 participants with a negative CCTA. Among all participants in the CCTA arm, including those who did not undergo the imaging test, 10 (1.1 percent) experienced a myocardial infarction. Similarly, five (1.1 percent) participants in the traditional care arm experienced myocardial infarction. Compared with participants in the traditional care arm, those in the CCTA arm were less likely to have negative invasive angiography (29 versus 53 percent) and more likely to be diagnosed with coronary disease (9.0 versus 3.5 percent).
"Nearly 6 million patients arrive [at the ED] annually in the United States for evaluation of chest pain at an estimated cost of more than $3 billion annually. Yet up to 85 percent of these patients do not have cardiac-related problems," says Harold I. Litt, MD, PhD, chief of cardiovascular imaging in the Department of Radiology at the Perelman School of Medicine at the University of Pennsylvania, in Philadelphia, and co-principal investigator of the ACRIN trial. "Prior research, including work by our university's research team, established that CCTA can rapidly identify the extent of coronary artery disease, if present, and suggested the safety of CCTA for clinical decision making."
"The trial results have significant potential to establish a new standard of care for low- to intermediate-risk patients, dramatically reduce health-care utilization, and lower medical costs," says Judd Hollander, MD, the trial's co-principal investigator and clinical research director in the Department of Emergency Medicine at the University of Pennsylvania in Philadelphia. "In addition to identifying patients who could be safely discharged, the trial showed that evaluation with CCTA compared with current practice led to fewer patients having cardiac catheterizations that were found to be unnecessary and identified more patients who truly required hospital care."
“The trial results have significant potential to establish a new standard of care for low- to intermediate-risk patients, dramatically reduce health-care utilization, and lower medical costs,” — Judd Hollander, MD
First of Its Kind
The benefits of ACRIN PA 4005 extend further than simply shortening a patient's stay. It represents the first use of an imaging test as a tool for stratifying low- to intermediate-risk patients in the ED with potential ACS. The increased rates of discharge home and reduced length of stay associated with CCTA led researchers to characterize it as more efficient than traditional care. Given that this patient group accounts for 50 to 70 percent of potential ACS ED presentations, the study concluded that a CCTA-based strategy can safely and efficiently redirect many patients home who would otherwise be admitted.
By allowing ED physicians to focus their attention on patients who need immediate care, CCTA has the potential to increase the efficiency of medical care provided in the ED. "We know that having patients in the ED who don't require emergent care actually serves to increase the mortality rate for other patients in the ED who are actually ill," elaborates Hollander. "CCTA could enable us to discharge a large subset of chest pain patients after finding they are not at risk for a cardiac event and thus enhance the care for all ED patients."
Prior studies documenting the outstanding negative predictive value of coronary calcium scoring, the correlation between CCTA and routine cardiac catheterization results and the ability to obtain both calcium scores and visualization of the coronary arteries with CCTA led researchers to focus on CCTA's potential for identifying patients without disease. Researchers designed and performed the study to provide confirmatory evidence of CCTA's safety so that ED physicians could feel confident about triaging low- to intermediate-risk patients according to the scan's results. Patients without significant coronary disease on CCTA were hypothesized to have a less than 1 percent rate of 30-day cardiac death or myocardial infarction.
Significant secondary aims of the study include comparisons of the two arms with respect to discharge rate and length of stay during the initial ED visit and 30-day death, myocardial infarction, revascularization, and resource utilization. To mirror real-world clinical conduct, patient management following diagnostic testing was at the discretion of the treating clinician, and participant selection was limited to patients expected to be admitted to the hospital or undergo additional testing.
The ACRIN PA 4005 trial is one of the group's first research efforts to receive funding from the ACRIN Fund for Imaging Innovation, which was established in 2008 to broaden ACRIN's clinical trials research portfolio. "The announcement of these practice-changing results is very exciting and demonstrates how effectively the ACRIN Fund has leveraged resources to support important imaging science," says Mitchell Schnall, MD, PhD, ACRIN network chair and the Matthew J. Wilson Professor of Research Radiology at the University of Pennsylvania. The study was also funded in part by a grant from the Pennsylvania Department of Health. The department specifically disclaims responsibility for any analyses, interpretations, or conclusions.
By Nancy Fredericks, MBA, and Julie Catagnus, MSW, ELS