A large urban healthcare system that implemented coronary CT angiography (CTA) to triage low-risk chest pain patients in the emergency department cut length of stay in half. The system also reported a very low downstream testing rate for patients with negative results and mild stenosis, according to a study published in this month's issue of the American Journal of Roentgenology.

Acute chest pain accounts for more than 6 million visits to emergency departments in the U.S. annually, and typically sets off a chain of downstream testing that is both costly and time-consuming. Early data suggest CTA offers a new model that can expedite safe and more cost-effective discharge.

Ricardo C. Cury, MD, from Baptist Health of South Florida in Miami, and colleagues devised a prospective study to determine whether coronary CTA provided a safe and reliable assessment tool for triage of chest pain patients with low- to intermediate-risk of acute coronary syndrome (ACS). The researchers also evaluated the efficacy of a five-level chest pain protocol that referred low-to-intermediate risk chest pain patients to CTA. Outcome measures included downstream testing, 30-day outcome, length of stay, time for diagnosis and radiation dose.

The researchers enrolled 529 patients to CTA based on an in-house chest pain protocol between January 2009 and October 2010. These patients had negative cardiac enzyme results, normal or nondiagnostic ECG results and a thrombolysis in myocardial infarction risk score of 2 or less. After CTA, patients were grouped into one of four risk groups: 0, low risk; 1, mild risk; 2, moderate risk; and 3, severe risk.

A total of 88.5 percent of patients were classified as low or moderate risk of ACS and were discharged from the ED after CTA. The downstream testing rate in this group was 3.2 percent, and there was one major adverse cardiac event (MACE) in 30 days. This is a potential cost-savings, according to Cury et al. However, the researchers cautioned only low-to-intermediate risk patients should be referred to CTA as high-risk patients could spur a cascade of consecutive downstream testing.

Among the 25 patients in the moderate-stenosis group, nine underwent SPECT-MPI and seven underwent invasive coronary angiography. No MACEs were reported in 30 days.

Thirty-six patients were found to have severe stenosis on CTA, and 32 underwent further testing. These tests showed myocardial ischemia in 30 patients, and three MACEs and 17 percutaneous coronary interventions were reported in this group.

Cury and colleagues calculated a 99.8 percent negative predictive value of CTA to rule out MACE and ACS.

The researchers also described the in-house chest pain protocol as “highly efficient in reducing patient turnaround times.” From 2009 to 2010, median time for diagnosis fell from 27.2 to 12.8 hours. In addition, time from CTA request to CTA reporting dropped from eight to 6.8 hours. Cury et al attributed this decline to a learning curve on the part of CT technologists and radiologists.

Radiation dose fell from 13 mSv in 2009 to 5.5 mSv in 2010, after prospective triggering was deployed.

“The main advantage of using CTA in the ED is its fast availability that leads to decreases in length-of-stay and total time for diagnosis when using a dedicated chest pain protocol for CTA implementation,” concluded Cury and colleagues.