Only two of 625 patients presenting to the emergency department with chest pain and coronary artery calcium scores of zero had any adverse events within a six-month observation period, indicating that they can be safely sent home without further cardiac testing, according to a new study from Methodist DeBakey Heart and Vascular Center in Houston.
Coronary CT angiography (CTA) has proved to be a highly effective triage tool for ruling out coronary artery disease for individuals presenting with chest pain, but coronary artery calcium (CAC) scoring with CT is a simple, readily available test that has demonstrated high prognostic value for predicting adverse cardiac events in decades of research.
DeBakey cardiologist Dr. John Mahmarian and colleagues found that a CAC score of zero correlates with excellent short-term outcomes and predicts a normal SPECT myocardial perfusion imaging (MPI) study, which is a more advanced imaging test that is usually performed after CAC scoring.
Mahmarian and colleagues conducted a prospective observational study of 1,031 stable patients presenting to the emergency department with chest pain of uncertain etiology. Those with normal initial troponin levels, nonischemic electrocardiogram, and no history of coronary artery disease underwent stress SPECT MPI and coronary artery calcium scoring within 24 hours of their admission.
The researchers defined cardiac events as an acute coronary syndrome during the index hospitalization or in follow-up. CAC scores were assessed in relation to SPECT findings and cardiac events.
Results over the six-month observation period showed that patients without coronary artery calcium had a far lower incidence of adverse events. Among the 1,031 patients enrolled, 61% had a mean CAC score of zero. The frequency of abnormal SPECT results ranged from 0.8% for those with CAC scores of zero to 17% of those with CAC scores greater than 400.
Cardiac events occurred in 32 patients (3.1%) during index hospitalization (n = 28; mean, 7.4 months) or following discharge (n = 4; mean, 3.3 months). But only two events (0.3%) occurred among the 625 patients with a CAC score of zero. Both of these patients developed elevated troponins during their index visit, but had normal serial electrocardiograms and SPECT studies and no cardiac events at six-month follow-up, the authors noted.
"Our results suggest that patients with a CAC [score] of zero can be discharged home, without further cardiac testing," the researchers concluded.
By Eric Barnes
By AuntMinnie.com staff writers
February 10, 2010
Coronary calcification is a poor gauge of treatment efficacy, December 17, 2009
Symptomatic patients with zero CT calcium scores still have cardiac events, October 2, 2009
Coronary CTA beats calcium scoring for short-term prognosis, August 14, 2009
Coronary artery calcium independently predicts risk in CAD patients, July 29, 2009
Zero calcium means good outcomes, even with undetected plaques, July 23, 2009
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