By Charlene Laino
NEW ORLEANS -- November 11, 2008 -- Coronary computed tomography (CT) angiography is useful for the early triage of patients who present with acute chest pain at the emergency department, suggest results of a double-blind, observational cohort study presented here at the American Heart Association (AHA) Scientific Sessions.
Six million Americans present to the emergency department with chest pain annually, reports Udo Hoffmann, MD, Cardiac MR-PET-CT Scan Program, Massachusetts General Hospital, Boston, Massachusetts.
"Current risk stratification techniques, including electrocardiograms [ECGs], initial biomarkers, clinical presentation, and traditional risk factors, do not allow us to safely triage these patients," he said.
"In 50% of patients with acute chest pain and low to intermediate likelihood of acute coronary syndrome, CT is completely negative -- that is, it found no plaque and no stenosis. The absence of coronary artery disease enables their early and safe discharge from the emergency department," he explained.
Dr. Hoffmann and colleagues conducted a study to determine if coronary CT angiography could aid in the early triage of patients with acute chest pain but with an inconclusive initial emergency department evaluation. He presented the results of the study on November 10.
The study enrolled 368 patients with acute chest pain, no evidence of myocardial ischaemia on initial ECG, and normal initial troponin levels.
Prior to hospital admission, all patients underwent 64-slice, contrast-enhanced, coronary CT angiography. Both caregivers and patients were blinded to the results of the examination.
Results showed that 185 patients (50.4%) had neither plaque nor stenosis, while 68 patients (18.4%) had significant stenosis that was detected or not excluded. Another 115 patients (31.2%) showed evidence of nonobstructive plaque.
"No patient without plaque developed acute coronary syndrome," Dr. Hoffmann said.
However, 24 patients (35.3%) with significant stenosis detected or not excluded and 7 patients (6.1%) with nonobstructive plaque developed acute coronary syndrome.
When used as triage criterion, the presence of any plaque on coronary CT angiography was associated with 100% sensitivity, 100% negative predictive value, 54% specificity, and 17% positive predictive value for acute coronary syndrome.
Use of the presence of more than 50% stenosis as a triage criterion had 77% sensitivity, 98% negative predictive value, 87% specificity, and 35% positive predictive value for acute coronary syndrome.
"In patients with acute chest pain who are at low to intermediate likelihood of acute coronary syndrome, CT can be very effective for early triage," Dr. Hoffmann concluded. "If no disease is present, it is safe to discharge them."
[Presentation title: Usefulness of Coronary CT Angiography in the Early Triage of Patients With Acute Chest Pain. Abstract 2004]
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