Study objective: Coronary artery calcium scoring (CACS) is a simple and readily available test for identifying coronary artery disease. Our objective is to evaluate whether a CACS of zero will identify chest pain patients who can be safely discharged home, without need for further cardiac testing.
Methods: This was a prospective observational cohort study conducted at an urban tertiary care hospital of stable patients presenting to the emergency department (ED) with chest pain of uncertain cardiac cause. Patients with a normal initial troponin level, nonischemic ECG, and no history of coronary artery disease had stress myocardial perfusion imaging (SPECT) and CACS within 24 hours of ED admission. Cardiac events were defined as an acute coronary syndrome during the index hospitalization or in follow-up. CACS results were assessed in relation to SPECT findings and cardiac events.
Results: The 1,031 patients enrolled (mean [SD] age 54 [13] years) had a median CACS of 0 (61% with CACS of 0). The frequency of an abnormal SPECT ranged from 0.8% (CACS of 0) to17% (CACS>400). Cardiac events occurred in 32 patients (3.1%) during the index hospitalization (N=28) or after hospital discharge (N=4) (mean 7.4 [3.3] months). Only 2 events occurred in 625 patients with a CACS of 0 (0.3%; 95% confidence interval 0.04% to 1.1%). Thus, 2 of 32 patients with a cardiac event had a CACS of 0 (6%; 95% confidence interval 0.8% to 21%). Both of these patients developed increased troponin levels during their index visit but had normal serial ECG and SPECT study results and no cardiac events at 6-month follow-up.
Conclusion: A majority of patients (61% in our sample) evaluated for chest pain of uncertain cardiac cause have a CACS of 0, which predicts both a normal SPECT result and an excellent short-term outcome. Our results suggest that patients with a CACS of 0 can be discharged home, without further cardiac testing.
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