CT assesses risk for emergency room chest pain patients

Gwynne D. Koch

More than 4 million Americans who visit emergency departments for chest pain each year are admitted to the hospital for observation and further testing to rule out acute coronary syndrome. Research findings from the University of Pennsylvania’s School of Medicine in Philadelphia suggest that coronary CT angiography may offer a quicker and more cost-effective method for screening patients who can safely and immediately be discharged from the emergency department.

Screening for quicker discharge

Dr. Anna Marie Chang, a physician in the department of emergency medicine, and colleagues compared four evaluation strategies, analyzing cost of care, length of stay, diagnosis of coronary disease and safety, as determined by the occurrence of heart attacks or patient death within 30 days of the hospital visit. The work was presented in June at the annual meeting of the Society for Academic Emergency Medicine in Washington.

The 643 patients studied were divided retrospectively into four groups that were frequency matched. Two groups received coronary CT angiography, one in the emergency department and the other after an observation unit stay. The third group had a stress test after an observation unit stay, and the fourth group was admitted to the hospital for inpatient evaluation.

Coronary CT angiography may provide a cost-effective alternative for identifying patients with chest pain who are at low risk of cardiac problems, such as blocked arteries, which lead to heart attacks. The arrow on the CT image indicates low-density noncalcified plaque that is causing a narrowing of the proximal right coronary artery.

Using a standard acquisition protocol that minimizes radiation exposure, the researchers obtained high-resolution CT scans using either a single- or dual-source 64-slice scanner from Siemens Medical Solutions of Malvern, Pa. An initial unenhanced electrocardiogram-triggered scan was obtained to identify patients who could receive the CT angiogram. Following an intravenous injection of nonionic iodinated contrast through a peripheral vein and after the appropriate scan delay, an electrocardiogram-gated acquisition through the heart was performed.

Patients with negative scans — those showing no evidence of dangerous blockages in the coronary arteries — were discharged. Thirty days later, none of those discharged patients had experienced a heart attack or had died from cardiovascular-related causes. Compared with the other strategies, immediate CT angiography was shown to be as safe, to identify as many patients with coronary disease, to have the lowest cost and the shortest length of stay, and to enable the majority of patients to be discharged.

The scientists concluded that larger prospective studies should be conducted to confirm the technique’s safety before it is used in place of other strategies to rule out acute coronary syndrome.