Simple Calcium Test Negates Cardiac Event Likelihood

Coronary artery calcium scoring (CACS), a simple and inexpensive noninvasive test can determine whether it is safe to send home a patient who arrives at the emergency room (ER) with chest pain.

Researchers at the Methodist DeBakey Heart & Vascular Center (Houston, TX, USA) conducted a prospective observational cohort study at The Methodist Hospital (Houston, TX, USA) of 1,031 stable patients presenting to the ER with chest pain of uncertain cardiac etiology. Patients with a normal initial troponin level, a nonischemic electrocardiogram (ECG), and no prior history of coronary artery disease (CAD) had stress myocardial perfusion imaging (SPECT) and CACS performed within 24 hours of ER admission. The CACS results were assessed in relation to SPECT findings and cardiac events, which were defined as an acute coronary syndrome during the index hospitalization or in follow-up.

The results showed that 61% of the patients evaluated for chest pain of uncertain cardiac etiology had a CACS of zero, which predicted both a normal SPECT and an excellent short-term outcome. The frequency of an abnormal SPECT ranged from 0.8% (when CACS was 0) to 17% (CACS of over 400). Cardiac events occurred in 32 patients (3.1%) during the index hospitalization or following hospital discharge. Only two events occurred in 625 patients with a CACS of zero, and both of these patients developed elevated troponin levels during their index visit, but had normal serial ECG and SPECT results and no cardiac events at six-month follow-up. The researchers concluded that properly selected patients who have a CACS of zero could be discharged home without further cardiac testing. The study was published early online on February 5, 2010, in the Annals of Emergency Medicine.

"It is imperative to accurately diagnose patients who come to the emergency department with chest pain,” said lead author cardiologist John Mahmarian, M.D. "Unfortunately, diagnosing chest pain is often expensive and time-consuming. This new data could save millions of health care dollars and countless hours spent waiting on unnecessary tests.”

CACS is performed with a computed tomography (CT) scan to create a detailed image of the heart, showing calcium build up in the coronary arteries; the images can be read almost immediately after the scan. A CACS of zero correlates with an excellent short-term outcome and predicts a normal SPECT, which is a more advanced imaging test that is usually done following a CACS test.

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Methodist DeBakey Heart & Vascular Center