30-Day Risk for Patients with Chest Pain Effectively Predicted by CT Angiography

Coronary computed tomography angiography (CCTA) can rapidly and effectively determine which patients complaining of chest pain at an emergency department (ED) can safely be sent home.

These findings were presented in March 2012 at the American College of Cardiology’s 61st annual scientific session, held in Chicago (IL, USA). Of the 6 million annual visits to US emergency departments (EDs) for chest pain, up to 85% are not actually caused by heart problems. A lot of progress has been made in identifying high-risk patients, but low-risk patients pose evaluation challenges that can be expensive in risk, discomfort, and recovery time for the patient and in healthcare resources. Most of these patients are admitted for standard “rule-out” care that typically requires a hospital stay of about 24 hours and a stress test, with or without imaging. If findings are positive, the next step is likely to be cardiac catheterization, an invasive and time-consuming procedure that involves threading a thin tube into the heart.

ED physicians have a standard for discharging a person with chest pain: less than 1% risk of heart attack or heart-related death over the next 30 days. For patients with no known heart disease, the major factor in considering that risk is whether any heart arteries show blockage of 50% or more. Cardiac catheterization is a conventional imaging technique used for this purpose.

“When EDs are crowded, all patients suffer,” said Harold I. Litt, MD, PhD, chief of cardiovascular imaging in the department of radiology at the Perelman School of Medicine, University of Pennsylvania (Philadelphia, USA) and the study’s lead investigator. “Our primary goal was to power the study statistically to prove the safety of CCTA so that ED physicians could feel comfortable sending home patients who have negative results from CCTA scans, and we did that.”

ACRIN PA 4005 is the first cardiovascular study conducted by the American College of Radiology Imaging Network (ACRIN). In this phase-4 trial, 1,393 patients at five centers were randomly assigned to conventional rule-out care or CCTA in a 1:2 ratio. Healthcare providers at each site made all decisions about tests and treatment for the traditional care group patients on an individual basis. The CCTA group followed a three-part protocol: (1) tests to measure blood levels of two substances associated with heart damage and risk of heart attack or stroke, (2) CCTA, and (3) discharge if test results were negative.

None of the 640 patients with a negative CCTA had a heart attack or died within 30 days after discharge (30-day event rate of < 1%). These findings apply to patients at low-to-intermediate risk. People who have a known history of heart disease require a much more comprehensive evaluation before they can be sent home safely, Dr. Litt emphasized.

The study also showed that CCTA was a better indicator than stress tests of finding patients with coronary artery disease (9% vs 3%). “Stress tests are positive only when there’s enough blockage to impair blood flow,” Dr. Litt said. “CCTA lets you actually see atherosclerosis and stenosis, even if that’s not what’s causing your chest pain that day.”

Lastly, the trial revealed distinct advantages for CCTA compared with traditional care in several categories of resource use: number of patients discharged rather than admitted to the hospital (50% vs. 23%), median length of stay (18 hours vs. 25 hours) and median length of stay for patients who had a negative CCTA or stress test (12 hours vs. 25 hours).

Researchers will be collecting data regarding costs associated with these findings and talking with both groups to analyze 30-day and one-year utilization and cost-effectiveness. In-hospital and 30-day cost data are expected within six months. Researchers also recorded data about arterial plaque that will be analyzed in the future.

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Perelman School of Medicine, University of Pennsylvania